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 researcheradvises that solar cells and solder connections must be “vacuum sealed”in an air-tight sandwich between backing plate and glass panel thatface the sun. Without that seal, the components, especially thecopper, will corrode and fail in a few years.
Building Inspector I checked with local buildingdepartments in 12 cities and counties across the Western US. Officialsreport that they require an Underwriter Laboratory Label (UL) on solarpanels before issuing a permit for installation and connection. (Mostelectric devices in your home have a UL label.) This is to protect youfrom electric shock or fire from an untested product).
Reducing Your Energy Bill I checked regulationsonline for five major utilities in California and Oregon. Localutilities won’t connect panels and an inverter to utility meterswithout a UL label, a building permit, and a sign-off by a buildinginspector. In some cases, they may require a licensed contractor. Without connection to an electric meter (net metering), reducing yourelectric 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 panelsthat range from 180 to 220 watts. A 3 kilowatt residential systeminstalled by a contractor would require about 15 panels. A home-builtsystem 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 offthe grid is a romantic idea. But remember, the local utility is yourback-up power at night and when the weather is bad. Of course, youcould buy a set of batteries and related equipment and convert yourlighting, electronics, and appliances to run on 12 volt DC power. You’d have to forego air conditioning, and likely purchase a propanerefrigerator.
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 useenergy. I’m as impatient as anyone to get the job done. Though I havethe 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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