Many Questions about Build-It-Yourself Solar Panels

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At Buildings & Energy LLC, most of our work centers on commercial sites.  But recently, we’ve been deluged with offers for “kits”, videos, and books on how to build solar panels in your garage and save on your energy bill. At the very least, it sounds like a fun project - perhaps even a science project for a local school.  After all, some solar panel manufacturers in China assemble their panels by hand.  What could go wrong?

However, after talking to building officials, a solar researcher, state incentive agencies, and a tax attorney, I have serious concerns. Corrosion & Failure  Our solar researcher advises that solar cells and solder connections must be “vacuum sealed” in an air-tight sandwich between backing plate and glass panel that face the sun.  Without that seal, the components, especially the copper, will corrode and fail in a few years.

Building Inspector  I checked with local building departments in 12 cities and counties across the Western US.  Officials report that they require an Underwriter Laboratory Label (UL) on solar panels

before issuing a permit for installation and connection.  (Most electric devices in your home have a UL label.)  This is to protect you from electric shock or fire from an untested product).

Reducing Your Energy Bill  I checked regulations online for five major utilities in California and Oregon.  Local utilities won’t connect panels and an inverter to utility meters without a UL label, a building permit, and a sign-off by a building inspector.  In some cases, they may require a licensed contractor.   Without connection to an electric meter (net metering), reducing your electric utility bill is not possible.

Let’s Compare Real-life Costs  Installed cost in Oregon is about $1,800 to $1,900 per 200 watt panel for a small system. However, after state and federal incentives, the cost of a professionally installed panel drops to about $400 after the first year of operation.

Materials cost for a 100 watt panel made at home is about $300 (check retail silicon cell costs on the open market).  In Oregon, a build-it-yourself panel might save about $100 per panel.

It Gets Worse  Home-made panels are about ½ as efficient as commercial panels that range from 180 to 220 watts.  A 3 kilowatt residential system installed by a contractor would require about 15 panels.  A home-built system would require about 30 panels.  Since you’ll need twice as many panels the $100 savings per panel evaporates.

Add an inverter, rolls of wire, and installation, and the professionally installed system can cost less than build-it-yourself system.

Disconnect from the Local Power Grid?  Living off the grid is a romantic idea.  But remember, the local utility is your back-up power at night and when the weather is bad.  Of course, you could buy a set of batteries and related equipment and convert your lighting, electronics, and appliances to run on 12 volt DC power.  You’d have to forego air conditioning, and likely purchase a propane refrigerator. 

 So, take a minute to ask yourself:

• What is your labor worth? Do you want to spend a couple of weeks on your roof?

• How skilled are you at the required tasks (soldering a tight bond, for example)?

• Are you prepared to give up air conditioning and power back up?

There’s no question that we need to reform the way we source and use energy.  I’m as impatient as anyone to get the job done.  Though I have the skills and experience to do it myself, I’m not convinced that building one panel at a time (in your garage) is going to lead to a renewable future.

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