My DIY Solar Power Setup – Free Energy for Life

It is pretty well known at this point that Mr. Money Mustache is enamored with solar power. Besides the obvious Sci-Fi coolness of it (Electricity, Satellites, Futuristic Robots!) and the eco-friendliness of it (energy with zero noise or pollution), in the last five years the money side of things has finally matured, so that solar power is now the cheapest way to make electricity – even before you account for the added bonus of any available subsidies and the benefits of pollution-free living.

A Watt of Solar Panels: From $100+ to under fifty cents (2017) in less than my lifetime (image source cleantechnica). And the 2017 number for the blue side of the graph hit over 95,000 MW.

It works for individuals: In many cases, if you can get a good rack of solar panels on your roof, your monthly savings will be equivalent to making an investment that performs better than the stock market. But the numbers look even better as your solar setup becomes larger, like if you’re running a solar energy utility or a community solar farm.

Related: In recent Colorado Energy Bids, Solar energy is the cheapest option, even when backed by battery storage (Vox).

The fun part of this for me has always been the physics. Ever since I learned how much energy the Sun shines onto our planet’s surface (about 16,000 times more energy than all of humanity consumes, even with our current bloated habits), I have been certain that a mostly-solar-electric world was inevitable. The only obstructions were human inertia and politics, which are temporary. Physics is forever.

For example, consider the following map showing the tiny amount of our deserts we would need to cover with solar panels to replace all energy consumption (electricity, oil, gas, nuclear, hydro, wind, etc)

Fig. 1: Tiny land area required to power all of humanity. (image source)

And it’s actually even better than that: the image above assumes an old-school solar panel efficiency of 8%, whereas 18% is now a standard rate. So you can cut the black dots in half again, and then chop a few more times to account for the other existing clean energy sources.

And of course, you don’t have to concentrate the panels and run giant power lines everywhere as implied by the map. You can stick solar panels virtually anywhere and they will start working like little employees for you, tirelessly cranking out energy (which is equivalent to money) automatically.

Which is of course the real subject of this article.

My DIY Solar Project

The new solar array at the MMM HQ workshop generates more than enough power to run the whole property year-round, plus charge the electric cars of the various members.

So naturally, I have always wanted to have my own solar power farm. Until now, various excuses kept me from getting it done: no great places to put panels on the roof of my main house, slightly unfavorable local regulations, but mainly a lack of knowledge of exactly what to buy and how to install it.

I vowed that whenever I finally got this project done, I’d write up a report to you, to spare you some of the research and time consumption that I had to go through.

So let’s get into it!

Part One: Show me the Money

As you can see from the picture above, I’ve started by building a relatively small solar array. There are twelve panels, each about 40 x 60 inches. Each one generates 300 watts of electricity when the sun shines, and when you run the numbers for my climate, the whole setup will crank out about 6100 kWh/year of electricity, a chunk which is worth about $732 per year at average US power prices.

Pretty amazing – enough energy to run my coworking space and Mrs. MM’s adjacent retail store… from a chunk of pretty black glass that is about the same size as a single car parking space!

Meanwhile, the wholesale cost of this equipment broke down roughly like this:

  • 12 solar panels at $130 each: $1656 (a total of 3600 watts at 46 cents per watt)
  • 12 Optimizer modules (which increase power output during partial shade): $650
  • One SolarEdge 6 kW Inverter (converts the DC from the panels to AC for the grid): $1102
  • Various brackets, mounting racks, bolts, and wiring stuff: $460

So my total cost, due to the very good luck of having a friend who is both a dedicated Mustachian and the owner of a booming solar company, was $3900.

That’s the best case, but even after you add normal profit margins plus a 30% tariff that The Donald recently levied on solar panels (and remember the panels are thankfully only half the cost of the system), you can still buy a similar Complete kit for $5000 or so.

When you’re measuring the annual return on your investment (or “payback period”), there’s only one thing that matters on the cost side: price per watt. I ended up building this system at about $1.08 per watt, which is low by today’s standards but will soon sound high.

And remember, there are usually tax incentives to cut this cost further  – you can take 30% off the top of this cost due to the US Federal “Investment Tax Credit (ITC)“, and possibly more from your state and local government or utility.

The Great Solar Journey to Durango

Last year, I met a badass Mustachian entrepreneur named John. He was in Longmont to visit some family here, but his real home base is in Durango, Colorado where he runs a successful solar installation company called Shaw Solar. There are a million stories that need to be told about this man, but for now we’ll start with this one.

Knowing how long I had been interested in a do-it-yourself solar project, John decided to step up and help me get it done at last. We went over technical details, calculations, strategies, and costs. All of this culminated in me taking a spectacular roadtrip to Durango along with another local friend, in May of 2017.

It was quite a trip, for much more than the acquisition of solar panels and advice. Durango is a stunning little town, and it turned out that John lives in a community of equally impressive siblings and friends – for example his brother Charles who DIY-renovated a 50,000 square foot school over a 20-year period, which has now become the jewel of Durango’s downtown.

Time For the Build

I drove back from this trip full of confidence and energy… only to end up storing the solar panels for months in my studio building as I worked to finish higher-priority parts of the Headquarters building, then waited for the time and motivation to plow through the building permit application.

It took another visit from John to really kickstart the project, and once we worked through it I realized my worry was completely unfounded – if you know what you’re doing, a simple solar array can be completely installed by two people in a less than a day’s work. Here’s what we ended up doing.

Step Zero: Research and Permit

Begin with the end in mind. The amazing Kari Spotts (LPC’s lead of renewable power metering) helps me swap in a new dual-flow electric meter at the successful completion of this project.

This is the part that stops most people before they even begin. The quickest shortcut is that if you’re not interested in these details, find someone who is, to catapult you through it. But if you have enough curiosity to learn the details, here they are:

How big a system should I build? In general, the bigger, the better. The cost per watt goes down as your system grows, making it a higher annual yield on the investment.

“I don’t live in Colorado. How much juice will I get out of it where I live?” This part is fun: The National Renewable Energy Lab runs a great, free calculator called PVWatts that does it all for you: factoring in average weather and solar angles in your area, even allowing you to specify solar panels placed at any crazy angle you like. (In other words, your house doesn’t have to have a perfect South-facing roof).

“Do I need some of those Tesla Powerwall Batteries too?” No. Unless you’re building an off-the-grid cabin, in almost all cases you will want to “grid-tie” your solar array, so you can effectively sell your surplus electricity back to the power company (and thus, other nearby customers), cleaning up your whole town and saving the huge cost of batteries. The Powerwall works great if you want protection from power outages, however, and can even pay for itself if you live somewhere with a smart grid that allows day/night price arbitrage.

“How do I get a permit to build this thing?” Your city’s building department probably has a page describing how to apply. For example, here’s the one for Longmont. The trickiest part is generating a “one-line diagram”, but I cheated by just photoshopping my own details into the example provided with my city, leading to this result, which they approved without question.

Step One: Layout

I had a nice, simple roof that was already facing South, tilted up at a 30 degree angle, which is just about perfect for solar panels. But you can also put them on other slopes or flat roofs, and they still work surprisingly well.

I needed two rails for each row of panels, and the rails get supported by “L”-shaped brackets bolted into the roof. So I ended up with this configuration:

Laying out support brackets, rails, panels, and power inverter.

Important consideration: Because I was putting this on a garage roof (technically “unoccupied space”), I was able to squeeze them all the way to the roof edge. If you are installing on a house, your city’s fire code may require that you leave a 3 foot walking access around the edges. Sometimes it’s wise to think outside the box: a garage roof, a standalone ground-mounted rack if you have lots of unused land, or creating the new workshop/carport/garden shed you’ve always wanted in the sunniest part of your yard.

2: Install your Brackets and Rails

Once you figure out where to put the long “lines” shown above, you measure them out and snap chalk lines right over top of your existing roof material. Then, use some sturdy 2.5″ lag bolts and washers to hold down the L-shaped brackets that come with the solar racking kit. Pre-drill each hole, and inject in some “Through the Roof” sealant with a normal caulk gun before driving in those bolts – this creates a permanent watertight seal. (There are also special brackets to accommodate different roof styles like tile and metal).

Once the brackets are in, you simply use the supplied slide-in bolts and nuts to attach the long rails, straighten them up nicely, and lock it down. Doing all of this with a cordless impact driver makes it quick and clean.

3: Bolt down and connect the Optimizers if you’ve Got ‘Em

These are just little flat boxes that you connect to the top of each pair of rails, about 6″ from the eventual right edge of each solar panel. There’s one optimizer for each panel, and it acts like a babysitter – monitoring output from the panel, compensating for voltage changes when necessary (such as when shade hits that panel). You’ll notice that each optimizer has four wires protruding from it, and there’s one optimizer for each panel. This will make sense in the next step.

Optimizer mounting (face down), plus a good shot of the connections between roof, brackets, and rails. Note – a solar installer saw this and said he suggests you use flashings like this for extra protection on those L-feet.

Once all the optimizers are in place, you connect each pair of longer wires together with the incredibly convenient fast-click connectors. The positive and negative wires have differently shaped connectors so you can’t accidentally reverse them.

You end up connecting optimizers to each other, and each panel only to its host optimizer, like this:

Inverter to panel connections

If you have two lines of panels as I do, connect the far end of one line to the far end of the next line, so you end up with a long series of optimizers where both ends terminate with a loose wire on the end closest to your inverter.

Grounding is Important: Using the supplied grounding screw terminals, connect all the rails together with bare 10AWG copper wire. From that last terminal, you’ll be running a length of the same size wire down to the inverter.

4: Install the Solar Panels!

The bottom of each panel has two long output wires. Use clips and/or zip ties to keep the cables tidy so they don’t dangle onto the roof too much.

This step is better with two people, especially on a steep roof. Starting at the furthest corner from the location of your inverter, connect each the panel’s wires to the matching ones on its host inverter. Set the panels down straight, and use the click-in clamps that come with the racking system to clamp down the panel using your cordless drill/driver.

By the end of this step, you’ll have one or more tidy lines of panels with just two powerful-looking DC wires poking out the end, with connectors ready to go.

You’re now ready to build the final run of wire, which will enter a metal conduit and travel through your roof, down the side of your house, and into the inverter.

5: The Home Run:

Drill a 1″ hole in your roof and put a roof boot over top of it, tucked under the upper course of shingles. From there, your goal is to provide a protected path to get the high voltage DC wires from the panels, down to the inverter.

My city required 3/4″ metal conduit, which gave me the opportunity to learn about the various fittings and connectors that are part of working with conduit. I also bought a conduit bending tool, since there are many more outdoor electrical projects still on the docket for the MMM HQ building.

I ran a length of metal conduit up from the inverter and just beyond the roof boot, then transitioned to a downward-facing connector to some flexible conduit, just to keep the wires covered until they get under the panels. All three conductors including the ground are running through this tube. If doing it again, I’d suggest using a different conduit box for that transition. Also, you can switch from a bare ground wire to a stranded, insulated ground at that point – much easier to pull through!

6: Mounting The Inverter and Connecting it all to the Grid:

The part that sounds the most mysterious is actually one of the most simple:

  • Hang the inverter on the wall using the supplied bracket and a few screws
  • Connect the conduit and pull in the DC wires from the solar panels into the inverter’s connection box. On this Solaredge unit, there are nice spring clip terminals.
  • Do the same on the other side of the connection box, running a length of 8/3 household wiring (for outputs up to 40 amps) right into the breaker box, as if you were hooking up any other 240 volt circuit.

Inverter mounting, including the conduit going up through the roof (left), out to the main breaker box (right), required warning stickers (red), and how it’s hooked up inside (bottom)

7: Get it all Inspected and Power it Up!

The inspector will probably have a nitpick or two with your work. Stay strong and make any required corrections, and pass that inspection. Then you flip on the AC breaker, the DC power switch, the inverter’s main power switch, and poke through the menu systems to make sure everything is set to run the way you like it.

For this Solaredge system, I had to run a “Pairing” step with the power optimizers (see manual), and add a TP-Link Wireless Repeater/Bridge to allow the inverter’s wired Ethernet connection to join my existing property-wide Wi-Fi network. Which happens to be the the spectacularly good Google Mesh Wi-fi system.

So What’s Next?

From this point on, it’s all on automatic pilot. The system generates electricity every day, which reduces the Headquarters power bill down to zero. In winter, the days are shorter so we might consume more than we produce. But in summer, a large surplus will more than make up for it.

My inverter from Solaredge comes with a really nice monitoring features, available from both a phone app and any browser. Plus, you can share a public version of your page with anyone. Here’s one I made for the MMM-HQ array.

At the time of writing, I’ve had the system online for 27 mostly-January days, including a couple of writeoffs where the panels were covered in snow. It has still averaged about 10 kWh of electricity production per day, which is more than the average consumption of the whole facility. Put another way, the 265 kWh of electricity is enough to power an electric car for roughly 1000 miles of driving.

The monitoring tool also estimates about 410 lbs of CO2 emissions prevented, which is 0.2 tons or about $4.00 worth at current carbon cleanup rates. If you happen to care about running a carbon-neutral life (or business) as I do, this means the carbon offset makes your solar electricity about 15% more valuable in your mental accounting.

I can also double or triple the number of panels on this particular system (once I decide on a good place to put them) without changing the inverter or any of the grid-tie connections, which will greatly improve my annual return on investment. It’s just a LEGO-like plug and play to connect more panels to an existing rack of them, plus the inverter has a second set of inputs if you are running in some wires from a string of panels you have placed somewhere else.

My power company pays out a check for any overall surplus at the end of each year, purchasing the power at a wholesale rate. But many regions are more solar-friendly than this, giving you a full retail or even higher rate for solar-generated electricity as an incentive to go green.

The Final Word:

Solar energy is strangely fun to produce – most people report satisfaction far beyond just the monetary benefits. It gets you out there rooting for the Sun, and for your fellow humankind to follow suit and start harvesting it alongside you. So if you’ve been considering getting it done, the time is good.

Thanks again to John Shaw (shawsolar.com) for all the help with this project. If you have questions about the details or the industry in general, please put them in the comments and both John and I should be able to weigh in.

And if you happen to own a home or business around Durango, CO, contact Shaw Solar directly and tell ’em who sent you!

I also recruited some highly valuable help from an excellent more local electrician : Derek Miller who runs Omni Electric – highly recommended for projects in the Longmont/Boulder/Evans areas.

Rough Edges Alert: I’ve started by publishing this article in an unpolished form, so if you see incorrect details, please let me know and I’ll clean it up over time after publication.

  • Aaron February 11, 2018, 1:21 am

    This is a good article, and I’m all for solar, but it’s a bit lazy and dishonest to call these systems “zero pollution” without taking a look at the environmental cost of producing all these parts, and mining the required minerals.

  • Michael Bacarella February 11, 2018, 9:04 am

    The PVWatts calculator MMM linked is good, but a little overwhelming if you’re new to solar lingo. You can take out the guesswork by using Google Sunroof, which 3d models the satellite map of your property to figure out how much usable roof you have and breaks down costs and will attempt to model ROI for you. https://www.google.com/get/sunroof

  • David Classen February 11, 2018, 12:18 pm

    I live in an area that has frequent severe hail storms (north Texas) which cause a lot of damage. I’ve been hit twice in the last two years. How durable are the solar panels? My homeowners insurance covers solar panels but will only reimburse 50% of replacement costs. Basically I like the idea of solar panels but hesitate because the might require frequent replacement which would really distort the economics of such a project.

  • Terence February 11, 2018, 1:58 pm

    I think Mr.MM limits are showing here. No accounting for the negative effects of pushing utilities into the cost-base death spiral; for the end of economies of scale; for the fact that this “solution” is only available to individuals who are better off to begin with.

    I wish him luck with his project. But for those of us willing to look at the bigger picture individual-level renewables do NOT provide value for money. Take a look at any jurisdiction with microFIT programs and see the negative social consequences. More and more it seems like Mr.MM is drifting into the hard-libertarian ideology… what’s next for Mustachianism, setting up your own sewage treatment micro-plant so you can dodge municipal taxes? When did self-sufficiency morph into blatant selfishness?

    And when utilities try to pass on costs to net-meter customers, all we hear is whining about how they are “hostile” or “selfish”? Get real. These individual-level installations impose burdens on grid reliability.

    • Mr. Money Mustache February 12, 2018, 1:53 pm

      Also good points, but I think you’re misinterpreting my motivation here, Terence.

      I wrote here about DIY solar, but that’s just a flashy example which serves as an excuse to write about solar power in general. 95% of people who read this blog are probably not at the DIY level where they would attempt a project like this. But everyone needs to know that solar power is cheap, effective, easily backed up by storage, and should be the primary source of humanity’s energy.

      Also, we need smarter grids to accommodate renewable energy. Individual (and small utility) solar installations push our utilities to start using this already-existing technology more. It’s necessary: every household and business should be able to shift its flow throughout the day to help minimize peak power requirement and storage requirements.

      The more people are excited about the underlying technology, the more they will VOTE for governments that help facilitate this change, and then we both win – individualists and collectivists.

      • Married to a Swabian February 17, 2018, 5:44 am

        Absolutely, we need to update our ancient crumbling infrastructure, and adding monitoring and optimization to level out electricity demand, while accommodating grid tied renewables is the way to go. Germany is an excellent example.
        Thirty years ago, I interviewed with Commonwealth Edison in Chicago for numerous entry level engineering gigs. One of the positions was for a Marketing Engineer. My first question at the interview was: “Hey, you guys have a freakin monopoly here, what’d ya need marketang for?!”. The answer, was that working with large electric consumers like heavy industry to flatten out the demand curve ultimately saves them millions. At that time, they could avoid building new nukes possibly. Now they all go to third party providers who build “peaker plants” to cover the spikes in demand. LET’S GO SOLAR AND ELIMINATE THE NEED FOR THOSE AS WELL ! The future is in solar power, it’s that simple. Of course there will be political battles with the status quo utilities…and these are worth fighting.

  • Mike W February 11, 2018, 2:57 pm

    For those that don’t have a lot or location that would allow for solar panels installed directly, check out arcadiapower.com. I’ve used them for the past year. They purchase renewable energy credits up to 50% of your electricity use for free and offer at 1.5 cents/kwH to move to 100%.

  • Anonymous February 11, 2018, 5:26 pm

    Great job with the solar panels Mr. MMM! I keep going back and forth on whether or not to do the same type of project on my house in Grand Rapids, Michigan. We have plenty of sunny days in the summer to generate more than enough electricity through solar panels. But in the past 8 years or so, the Michigan state legislature made it illegal for residents to sell extra electricity back to power companies! How backwards is that? I am hoping the law will be reversed with a new change of political power in the elections this year. The savings would be much greater.

  • Melinda February 11, 2018, 5:47 pm

    Hi, what I am saying is not exactly relevant, but as I sit and read this blog, I am doing so in a caravan (trailer) in sunny Australia with the inverter turned on and the solar panels both on the roof and a freestanding 250 watt panel sending power to my batteries to give me the necessary power. Recently we had to replace the batteries costing AUS$1400 and in the last week new solar panels costing about AUS$1300 for 450 watts, not cheap but it does allow us to travel to many places where we don’t require 240 power to be hooked up. I do enjoy not having to rely on going to trailer parks for my electricity and often camp in off the beaten track places.

  • Dave Phillips February 11, 2018, 7:52 pm

    Great article thanks for all the information and details, we are going to install a system in the next 2-3 months (live on Spacecoast of Florida)

    Our oldest lives in Golden and works as a scientist at NREL

  • Josè Kuilan February 12, 2018, 1:36 am

    Hi, this is the first time reading this article. I have always been interested in solar panels but was hesitant due to the expensive work and materials but thanks to this article it’s now a reality and the right time to invest in such a project. My mother leaves in Puerto Rico and fortunately she’s one of the many people using a generator but it’s getting tobevery expensive, to noisy and you have to turn it of during the day time. I wander if we need a permit to do this type of a project in a smaller scale to accommodate my Mother?
    Thanks for the article,

    José Kuilan

  • FreeTim February 12, 2018, 8:56 am

    Someone has to state the alternative view, and promote anti-consumerism… was I sitting around wishing I had solar panels until this article? No, I wasn’t, so I’m not rushing right out and buying them. When I used a watt-meter to look at what we actually use for our electricity, it sure isn’t the lights.
    That said MMM, I realize YOU are already efficient (Kudos!), but for most readers who continue to use AC all summer long and DRYER for all their clothing needs, if they haven’t first taken their baby steps to reduce usage then “going solar” might encourage them to continue to be inefficient.
    Your article was awesome and thanks for all the detail, and positive tone, … just pointing out that one alternative method is to just STOP using clothes dryer all the time and air conditioning!
    Our biggest savings this year (thanks to you!) was to quit using AC … it wasn’t as harsh as we feared! We drink water in the summer and we’re comfy. – Thanks for reading :)

    • Alistair May 21, 2018, 7:40 pm


      This is an excellent point.

      There is some evidence that more energy efficiency actually leads to more consumption. (https://www.nytimes.com/2014/10/09/opinion/the-problem-with-energy-efficiency.html)
      Setting the AC higher (78F in my house in summer) or off certainly reduces consumption.

      There is also the energy pay back (if at all in some cases) for buying more energy efficient products.

      For example, take a 25 year old poor gas mileage vehicle. Keeping it around (i.e. repairs) will generally consume less energy than buying (i.e. making) a newer vehicle due to the energy used in the manufacturing process.

      Ideally, we’d have clean energy for manufacturing plants so that there is less of a disincentive to upgrade to more energy efficient products.

      That’s not to say there aren’t some other good reasons, such as safety, for getting a newer vehicle. Plus, we should also consider what happens to older vehicles as people upgrade. In an ideal situation, they would be taken out of use if we want to have cleaner vehicles on the road.

      Perhaps Uber/Lift/etc. will accelerate the elimination of inefficient vehicles on the road. Maybe they should incentivize greener drivers?

      But I digress.

  • O.S. February 12, 2018, 3:03 pm

    Great write-up, I was wondering why MMM had not moved to solar already.

    I invested in to my own installation last year in June. I can’t do anything with my own hands besides changing a light bulb so I went with solar professionals and started gathering quotes.

    It felt like the new gold rush.

    There are TONS of companies on the market because of the 30% tax incentives + subsidies from local utility companies ( I am from Austin, TX).

    They show you nice graphs with high ROI (min 10%) with inflated estimated power output and are making crazy margins thanks to the subsidies from the local utilities.
    I had to challenge their assumptions and make them compete against each other to finally pay 3.05 USD per watt before the 30% tax and local incentives. First quotes were at 4.00 USD.
    As you pointed out the cost of material is around 1 USD per watt and it takes 1.5 days to be installed, so the margins are yummy.

    The final net cost after all the incentives is 1.72 USD / watt and based on the first 8 months I expect a yearly yield of ~8%.
    Still an ok investment and at least I am now a bit greener than before !

    Funny fact, there are agreements with local credit unions to have your installation financed.
    I was hoping for low rates as the installation does depreciate very slowly and actually generates money, but the rates ended up being almost twice more than for a car, which does the exact opposite…

    Still some work to do to save the planet.

    Also, it is good to know that inverters can actually handle up to 35% more than their DC specs, so with a 6000 you are good up to ~8000 W of panels.

    • O.S. February 12, 2018, 3:40 pm

      Oh, and your system does allow you to mine SolarCoins too ! I know we like cryptocurrencies here…


  • RebeccaC February 13, 2018, 2:05 am

    We have had solar panels for about 5 years. We live in the south of the UK and have a south facing roof – but still, we don’t live in Texas. Our panels generate power all year round and will produce electricity on grey days just at a low rate. We sell the electricity generated by our panels to our power company under the government Feed in Tariff scheme which pays for all electricity generated, not just the surplus, at a guaranteed rate. We get payments of about £1,600 per annum – enough to pay for all of our electricity AND gas bills with a surplus to pay us back for the original capital invested. It’s been a great investment and many houses where we live have panels. One small issue is that the company installing the panels did damage a few roof tiles causing a leak and sorting this out has been more complex as the panels also have to be moved. It’s worth ensuring that any maintenance to your roof is done first and the area is in good condition.

  • MrMcLargeHuge February 13, 2018, 11:47 am

    You had me right up until you mentioned that the system was connected to the Internet. Is that a requirement for this particular setup? The security implications of IoT devices, such as this, are astounding, and not something I can look past. The largest botnet in the world is composed of IoT devices, like compromised routers, thermostats, and TVs, and I’d rather avoid that whole mess as much as possible.

    • Mr. Money Mustache February 13, 2018, 5:36 pm

      No – the internet connection is only needed if you want to monitor your energy production over the internet.

      It’s true that every new device, account, person, etc., that you add to your life adds a small pebble to your statistical chance of hacking risk. So you need to decide if it’s worth it for you. For me, it definitely is.

  • Jesse February 14, 2018, 8:17 am

    What a great a community. I would love to get a job installing these, with a mentor. Also, I would love a MMM construction course! 🤔

  • TomTrottier February 17, 2018, 2:06 am

    Ideally mirrors would reflect mainly the wavelengths the panel uses & be sturdy enough to stand the weather. Perhaps they would be more useful in colder areas – where they are more needed!
    Also, for efficiency, how practical would a rotating mount be – with an arduino-based sun tracker. This would be more practical on a ground-based system. Maybe use a disused equatorial astro mount?

    • Alistair May 21, 2018, 8:50 pm


      They actually tried mirrors on satellites about 10-15 years ago. Turns out the mirrors deteriorated much faster than expected.

      For terrestrial deployments, the additional heat build-up (mirrors and arrays) would have to be dealt with. Otherwise, it should work. It would be a little more obtrusive, visually and to the wind, however.
      I suppose, it’s ultimately situation dependent on how well it would really work.

  • TomTrottier February 17, 2018, 2:30 am

    Solar tracking may be even more beneficial in snowy areas if they go to vertical when the sun goes down – shedding all the snow!

  • Dan February 18, 2018, 8:36 am

    I guess solar is gaining momentum. Stodgy old me worked about 25-30 years off and on in nuclear and coal plants. I do not work on them now. If this was done on a non-distributed scale, I could see a lot of land being covered with solar panels. Now – next generation nuclear power which could use Thorium will take a lot less land. You’ll still need to run power lines, but you won’t have to build / maintain personal solar cells / inverters etc.

    These solar installations may cause power bills to rise. You still want a connection to the utility so the generation / transmission / distribution infrastructure will still be there. When the sun is not out, the utility will need to supply your power. (Unless you have magic long life batteries) This means they will still need a power plant somewhere.

    If Fear Uncertainty and Doubt (FUD) could be overcome, new nuclear plants could be built which are even safer than those out there today, use Thorium fuel which will essentially never run out is dirt cheap and produce far less nuclear waste than the reactors running today. These could operate 24 hours a day, be almost pollution free and would not need battery backup. They would not be too cheap to meter, but if not overly regulated could be very economical.

    Despite my last two paragraphs, I think solar power and wind power are quite intriguing. Small head hydro is also appealing.

  • warren February 18, 2018, 10:26 pm

    How did you get away with the Colorado net metering limit of 120% of the customer’s average annual consumption?

  • Shawn Laidlaw February 19, 2018, 9:23 am

    Great summary.

    Curious if you have thought about (or written about) investing in solar and/or clean energy alternatives, such as associated ETFs and/or specific companies. I am in a position where most of my ‘Stash will be established this year before retiring completely and trying to decide if I should dollar-cost average the stash over the next few years and, of course, what exactly to invest in. From what I can tell/hear currently, emerging markets are maybe the only that are currently undervalued and, also, clean energy seems to me a pretty inevitable long-term (hopefully shorter-term) outcome and is currently down a lot from just a few years ago (think President/coal big talk). Anyway, just wondering if anyone out there has dabbled more deeply than I yet.

  • Tomas February 19, 2018, 2:41 pm

    Long-time reader, first-time commenter!

    MMM, I’m curious, have you considered whether or not you could do a similar installation on your home, given that, per your old home rebuild article, your roof’s main slant is facing North? And, assuming it wouldn’t be optimal to go solar at home given that limitation, do you consider your overall setup at home to be optimal, including all of the built-in efficiencies with the higher ceilings and south-facing windows?

  • Alex Gontcharov February 21, 2018, 9:38 am

    Have you look at AC modules with micro inverters attached to the pv panel? http://www.lg.com/us/business/solar-panel/all-products/lg-LG330E1C-A5

  • Nick February 23, 2018, 8:40 am

    This is a really awesome post. When we looked around at installers last Spring, we didn’t factor in a DIY solution. We got a 6.3 KW system from Solar City and the total price ended up being $19,341, or about $3.07 per watt installed. After factoring in the federal tax credit, it ended up being $13,528.7, or $2.149 per watt. Although your prices for DIY blow mine out of the water, even at the $3 per watt I think it’s worth looking into as an option for those less electrically inclined. I wrote up a bit about our experience and the money considerations at my website above.

    You mentioned the credit but did not say f you applied for it, and what effect that had on your total cost?

    As far as snow removal, I can say that if your roof isn’t as steep, the snow isn’t going to just melt. These are solar panels, not hot plates. If I get a dusting (just outside of Pittsburgh, PA) and the temps are above 30, that will likely melt. However, we have had days of 2-4 inches of snow followed by a week or sub-20 temps, and that snow is just going to stay on there.

    Having 50% of the days out of the month of sub 1 kWh production was just not acceptable to me. I got a 23′ telescoping pole from Home Depot and tried using a rubber squeegee but it didn’t work as well as I would have liked. I picked up one of these http://www.roofrake.com/Productpages/snowpro2.asp and it works like a charm to remove the snow. There’s a bit of learning curve and it’s a minor arm/shoulder workout but well worth it. If your roof is a few stories up, this may not work for you, but for our ranch, it works very well.

  • james monroe February 23, 2018, 11:27 pm


    I think you meant optimizers instead of inverters in the first part of the sentence below:

    “You end up connecting inverters to each other, and each panel only to its host inverter, like this:”

    so it would read

    “You end up connecting optimizers to each other, and each panel only to its host inverter, like this:”

    which i believe matches the diagram

    be well

  • Matthew February 25, 2018, 9:15 pm

    Hi MMM,
    Here in Australia the payback period of installing a solar system on your roof is roughly between 6-8 years, depending on several variables, such as how big a system you install and what part of the country you live in.
    I’m certainly very keen, but I’m suffering from a bit of deer-in-headlights (or is that kangaroo-in-headlights ?) syndrome. The government and the electricity retailers keep changing the rules, the systems themselves keep getting more efficient, yet the overall cost for a 5kw system here is approx $6k. Sigh. I guess it’s just a case of biting the bullet and doing it, rather than waiting for the planets to align.
    (Melbourne, Australia)

  • veronica February 27, 2018, 9:16 am

    Not EXACTLY on topic, but an interesting read, thought I’d share it here as a reminder that “free energy for life” is not a blank cheque for “use as much of it as I want”.


  • Kristina March 7, 2018, 10:23 am

    MMM —

    Are those cool roofing shingles underneath those panels (i.e. reflective shingles that have an albedo effect)? They’re known to increase the efficiency of solar panels, though I wonder if they are a detractor in colder climes like Longmont. We’re all about them here in LA for indoor cooling purposes / better health index for the people inside, reduced energy demand during peak hours, and as result, less GHG.

  • Jessi March 8, 2018, 7:51 am

    I’m amazed you did this at $1.03 per watt. Everything I read estimates it at $7+ per watt. Maybe I need to move to Colorado to make my tree hugger self happier.

    • Anonymous September 26, 2018, 3:50 pm

      You can get a professionally installed system in NJ for about $3.00-$4.00 per Kwp. Energy Sage website has great info and I recommend contacting Amped On Solar if you are in central or south jersey. I spoke with many companies over the years and these folks are the best and trustworthy. You want to own your system and Luke can help explain. Good luck, Kevin Klinger

  • CHRISTINE BLAIS March 12, 2018, 8:01 am

    Hi mr. money mustache!

    I flip the homes I live in on the side to pay off my mortgage and I’ve always wanted to get a solar panel situation set up but am hesitant considering my nomad existence. Looks like the set up you’ve rigged is fairly permanent. Got any ideas on a semi-mobile option? I mean who needs a lawn right? maybe just set them out in the yard on some propped up OSB?

    • Mr. Money Mustache March 13, 2018, 5:35 pm

      The tricky part about this is that you need your city’s help to get a two-way electric meter (aka Net Meter) installed. They’ll want to inspect your solar equipment as part of this, and they only accept pretty heavy-duty and regulated setups.

  • Tim March 12, 2018, 6:38 pm

    That’s a great project you completed. I remember looking at a solar panel system with similar kWh performance back around 2005. I want to say the price was around $15,000 and the ROI took more than seven years for an area with more sunshine than where you live. Your system gets you to about five years. That number is making its way closer to the three year point, which could be a critical mass for how energy is delivered to residential and commercial buildings. By that time (as early as 2025?), I imagine few people will be drawing power from the the local plant during the day.

  • MortlandMoney March 13, 2018, 9:20 pm

    Thank you for taking the time to explain your solar system. I live/travel fulltime in my RV and purchasing a plug and go solar system has literally changed the way I live. In my first 3 months of owning my Renogy solar suitcase I have saved $1800 by not having to be stuck in an RV park.

  • Adam March 20, 2018, 11:15 pm

    Great article! You have inspired me to pursue this project on my own house. I’ve been on the fence about it but after reading your article I have been pushed off the fence onto the side of using a small portion of energy that the sun distributes for us.

    I am having difficulty with finding these products for sell to DIYers. I live in the State of Washington and it appears like the state is leaning towards creating jobs for residents of Washington which is great but why make it so difficult for a DIYer to complete a project like this? The incentives from the state are much higher if the consumer purchases equipment that was made in the State of Washington. I tried to purchase micro-inverters and was told they only sell them to “certified” installers. Supply houses seem to be supplying contractors with panels before a homeowner can have a chance. Hopefully supplies will build up and i can get my hands on some.

    Thanks for all of the inspiration. I won’t give up on making my DIY solar project a reality.

  • strummin March 26, 2018, 2:12 pm

    Thanks for this article, I have reread it 3 times now. I have had a TESLA representative give me a bid on my Arizona home and it costs 29K to build the just the solar panels, np batteries included, which is not a real deal unless energy prices really skyrocket over the next 30 years.. I have almost given up on it but think that I still have the ability to do a DO IT YOURSELF with the kit from this article. MMM, is there any reliable links out there for a ridge/rack system that can be run over TILE roofs? Thanks again!

  • Mike May 15, 2018, 2:55 pm

    The link for a complete kit to generate solar power lists the kit as no longer available. Do you have an updated source?

  • Meghan Anderson May 17, 2018, 11:17 pm

    I thought I remembered reading a post from you on solar roofs and I’m glad I found it. I am in the north Denver metro and Google’s Project Sunlight says I have 863 sq. ft for panels and 1704 hours of sunlight. The house faces east-west, which isn’t ideal so I’m not sure what to do? Hmm I could map it out, fight for the permit, etc. but the biggest obstacle is my fear of getting on the roof

    I’m wondering how your water is heated? Is it still gas?

    • Mr. Money Mustache May 18, 2018, 3:42 pm

      Hi Meghan!

      That sounds like quite a big area for solar panels (over 3x what I installed for this article), so you could choose to put half on the East slope and half on the West for all-day production.

      But as I tried to suggest in the article, DIY solar (or any solar) is not for everyone.

      The water in both my main house and the headquarters building downtown is heated by natural gas.

  • Jerry May 22, 2018, 10:28 am

    Thanks for the detailed post. I’ve been thinking of adding solar for years and hope to in the next year or so. I was thinking of incorporating wind as well. Have you looked into the small wind generators at all? Seems like it would be a good supplement in the evenings and on stormy days.

  • Sean May 29, 2018, 2:15 pm

    Has anyone had panels installed in South Jersey? I’m looking to get some installed and I would love to hear a good recommendation! Thanks!

  • alisongs July 17, 2018, 9:36 pm

    I had a neighbor do a DIY solar panel project – I was amazed and intimidated, so we decided to go the Solar City route. Oh Boy. When neighbors ask *us* about the panels, I say “look, we’re glad we did it for environmental reasons, but it doesn’t work out financially. So you have to do it because you think it’s a cool thing to do.” We are year #2 into this adventure and have come out even. But of course, the pitch was that we were going to save so much money because of the rebates, savings from PG&E, etc. I live in California. We have 300 days of sunshine and 36 panels. That’s a lot of panels and a lot of sunshine. It’s really the combination of the PG&E “true-up” (AKA extortion fee so we can us continue to use their system for natural gas) and the Solar City lease. But at least we’re green!

  • DLcygnet July 30, 2018, 10:08 am

    Wow! I can’t wait for the 1 year update on this. It looks like March was your best month so far – shocking since you should be getting more daylight in the summer. It looks like you’re pretty close to making that 508 kW average (6100 kW per year) – only double or triple the power you need. Does the electric company pay/credit you for the extra power above and beyond your usage? Is the system slightly less efficient when it’s hot out? I know most computers run better cooler. I really wish I didn’t have an east/west facing house… in the Pacific Northwest. Very exciting!

    • Mr. Money Mustache August 3, 2018, 11:12 am

      Yeah, I have been a bit surprised to see that power production is not highest in summer. Some of the factors I think are in play:
      – March was very sunny in this area (you can take a guess at sunny vs cloudy days by peeking into individual months)
      – In summer, the sun does a big circular arc across the sky/horizon, but the actual time it spends hitting the South-facing panels isn’t all that much longer. If I had fully moveable panel mounts, that would boost the summer a lot.
      – The hot temperatures of summer tend to decrease panel efficiency, by more than 10% compared to cool/cold days in winter.
      – The 30 degree angle of this roof is most effective sometime around April – in peak summer the noon sun is only about 17 degrees away from being vertical (we’re at 40 degrees latitude).

  • Anonymous September 26, 2018, 3:37 pm

    Hey Sean, I’m in SJ and recommend Amped On Solar. Are you a P SEG customer? I paid just under $3,000 for my system and save $1,400 annually. My cost was after incentives and the Fed rebate.

  • Doug November 20, 2018, 8:51 am

    Hi, I’m just wondering if you’ve ever taken an EMF meter to see if there’s any fields hanging around. Usually with the inverse square law the power density of the fields goes away quickly, but I’m interested in any datapoints. Thanks

  • daniel jensen November 26, 2018, 10:34 pm

    Thanks for your post. I just finished my DIY project. Here is an video explaining my the project IRR after correcting for income taxes and inflation. My project produced over 20% 15 year return. Here is a link to the video. https://youtu.be/MMvCV-j19GU . I have a bunch of videos I did while I was working on the project.

  • jay December 3, 2018, 10:37 am

    Thank you so much for this article! I’ve been on a mission to minimize all my expenses like crazy to work towards FI. I really want Solar and an EV, however the upfront cost has made me wonder if it is a smart move. And I really like it for the idealogical reasons. I’m waiting for my new house to be finished being built and then I’ll make the calculations. In the meantime I’ll be shopping for the highest efficiency appliances and a 2nd hand EV Car!

    Really loving your site and I’ve sent some links to a few people. I’ve burst out laughing a few times too, keep up the great work!
    Current Clown Car driver!

  • Moo stache December 5, 2018, 8:48 pm

    Interesting there is no mention of quarterly SREC (Solar Renewable Energy Credits) when our 17.2 kw system was first installed 8 years ago we received quarterly checks over $800. Now the bottom has dropped out and they are only worth $12 to $15 each, but it’s still a few hundred a year. You also own the SRECs, they do not have to be sold when you sell the property. As long as the system is producing power SREC payments will be sent. At the time our system was installed if a business paid for it the credit was issued as a check to the business ( business received about 65k back) balance of 43k was a heloc and paid off within 3 years. ( I hate interest). Since business rents our personal property it’s an improvement to our property the business paid for. The SRECS will in most probability go up again, and I hope to keep them in my personal name to supplement retirement FIRE income. We are in PA and without including SREC income our system paid for itself in 7.5 years. I looked st it as prepaying the electricity bill. The monthly pymt to pay the heloc loan was what I would have paid the electric company which would have equaled put at 7.5 years. I chose to have the biz pay it in less than half that to not pay the additional interest. I love our system. The 3 inverters happily hum and click and report info all day while the PV panels silently power our home and neighbors. The power co 0s out in May here, so we generally receive a check for $150 to $600 ( wholesale kw price) and then it restarts. Normally have no power bill other than $15 mo to be tied to grid til mid Dec when days shorten and Winter sun angle on panels isn’t ideal ( ground systems angles can be changed seasonally to capture most sunlight where our roof system can’t be). Then Dec to March about 75% of our power is covered by the PV system is guesstimate. 5 years ago we added solar hot water panels. Which I love as well, the tank is also linked to our wood stove so that heats a coil that feeds to the tank during winter. That system I expect closer to s 10 year payback ( it was 10k installed) but for many ppl would be the cheaper option than PV panels since it cuts s power bill about 25% with lower initial payout depending on size of system and will work indefinitely with virtually no wear and tear compared to PV. Just some thoughts I didn’t see others mention.

  • Bonald Blump April 4, 2019, 4:55 pm

    Solar Install,

    Did the city ask if your were a licensed installer?…..Does Longmont allow homeowners to DIY?

  • Michael Fallai April 8, 2019, 10:22 am

    Reading all of this (including comments) with great interest. I am considering the possibility of installing DIY solar in my backyard, on the ground in lieu of rooftop installed.

    1) much easier access than rooftop installed, including the possibility of easy expansion
    2) much of my backyard is gravel landscape anyway
    3) south roof is shaded by a giant sumac tree, I would hate to remove it in order to install panels
    4) eliminates any issues of the HOA or neighbors meddling/complaining (though state law makes it illegal for HOAs to prohibit in any way installation of rooftop solar)
    5) eliminates issue of having to remove panels in the event replacement/repair is needed to the roof.

    I am curious if anybody has input as to the feasibility of making ground-installed panels rotate to follow the sun. I did a video timelapse project a few years back for a commercial/industrial solar company and they told me the efficiency gain was around 10% vs. stationary panels. But is the additional complication/equipment worth the trouble?

    • Mr. Money Mustache April 8, 2019, 11:35 am

      Hi Michael, sounds like a cool project!

      In general, a tracking system will cost you more than it’s worth – better to just spend a portion of that money on more panels (which is why commercial installations are all fixed these days). But if you are really inventive and would enjoy the development process, I’m sure you could make it work.

  • Stephanie Miller June 10, 2019, 5:00 am

    I am having a Concrete Home built at the moment. I haven’t asked my contracters about this yet, but is there a way to have this attached to a flat roof concrete design?
    I have supported the clean energy movement and would be quite hypocritical if I did not find a way to apply it pon my own home. It is a new home so we can still make some modifications to the roof, for example. It is going to be a flat design which, I’ve heard is not the best for Solar energy. What can you tell me about this?
    Btw, if anyone in Massachusetts is looking to build an eco-friendly concrete house I can recommend my contractors: http://bluegreenbuildingconcepts.com/ They have been a pleasure to work with so far.

  • James August 22, 2019, 12:33 pm

    So this post was the impetus that going solar could actually pay for itself, and I got a DIY system on my barn (to feed the house) this month.Slightly used panels, Solaredge inverter, and optimizers from ebay. Someone had cut the connectors off the optimizers so I saved a fortune by buying those and replacing the connectors. Built rackign from aluminum angle from the scrapyard. Estimate 5 year payback (valuing my labor at $0…) But it’s cool to see my system backfeed the grid!

  • Xailter January 7, 2020, 3:43 pm

    Hi MMM,

    Thanks to this article (among other things), I took the plunge and got solar panels installed in late 2018. Have you since added to the system you built? I don’t know about the U.S. but the UK has a number of ‘add-ons’ you can buy to supplement your solar power consumption such as using the excess to heat your hot water, and of course solar batteries. Alas, in the UK, we do not really get any help from our government to install solar…

    I’ve done a first draft write-up of my own system here: https://igniting-fire.com/2020/01/07/the-solar-house-experiment-an-overview/ I plan to go into more detail on the different parts in future posts.

    Thanks for spreading the solar revolution!

    All the best,

  • Scott Diehl April 9, 2020, 11:59 am

    Great read. I clicked on your dashboard link and see that in 2 years now and you’ve produced 11 MWh! Quite a feat!

  • BH May 15, 2020, 9:48 am


    Do you know if this kind of project would work in Canada? I assume it would only work properly in the summer?



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