How to Run Your House Solely on Solar Power

Like Vitamin D for Your House
Solar panels attached to roof shingles create energy while being tested at the National Renewable Energy Laboratory (NREL) in Golden, Colo.
Solar panels attached to roof shingles create energy while being tested at the National Renewable Energy Laboratory (NREL) in Golden, Colo.
John Moore/Getty Images

To envision how solar power can provide enough juice for a whole house, it's necessary to cover a bit of the basics. We've probably all seen traditional solar panels by now -- flat, glare-inducing, unwieldy-looking things that jut from rooftops. They certainly aren't streamlined in any way, which makes them seem cumbersome. As we discussed, their ongoing refinement has gained some critical respect in the industry, but they still work about the same way.

As solar panels protrude from the precipice at various angles, they capture whatever sunlight is available, and convert it to DC power. An inverter converts the DC power to AC power (which is what we use to power electronic devices). And for people who want to completely power an entire home with the sun's rays, there are systems available to convert and store extra power in the form of battery energy. This way, the house still can have a source of power at night or in poor weather (but -- and this will be important later -- it can't cover the shortfall of a poorly-designed or inadequate system).

Solar shingles are a recently available option, a subtle, streamlined alternative to those telltale glaring flaps. They are solar panels, made from the same materials as traditional solar panels, that also happen to be shingles, and they look pretty much like a regular roof...perhaps just a bit shinier. Solar shingles, contrary to popular belief, can work even in weak or scattered sunshine conditions (which implies, but doesn't confirm, that shingles outperform panels in such circumstances). 

So, why does converting to solar take a bit of persuasion? Generally, houses in the United States can get heat either from gas or from electricity. For the sake of argument and purposes of this article, let's assume that someone gung-ho ongoing solar wants off the grid entirely -- and that means no gas or electricity. So, solar power needs to accommodate for heating, air conditioning (which, by far, is one of the biggest drains of power in a house), other parts of the house's infrastructure like lighting and vent fans, all major appliances (refrigerator, stove, washer and dryer), and other electronics like the microwave, stereo, television and computer. This list, of course, is by no means comprehensive (how many members of your family need to constantly charge their smartphones or tablets?), and there are a lot of variables. If your house is huge or you're a power hog who leaves the electronics on all day, you'll need a more intense solar setup. It would be nice to assume that anyone serious about performing this conversion is already pretty conscious of consumption and makes an effort to reduce power usage, like using insulated window shades instead of cranking the a/c, or foregoing a dishwasher that heats up and churns for hours. Right now, that's probably a fair generalization, but as solar goes more mainstream, the eco-conscious early adopters might not be the majority. The point is, you have to calculate all the electricity your house uses, and for the amount of time per day, and assemble a solar panel setup that can meet that demand. If it seems like too much, try cutting back on your consumption for a while and see if the numbers become more realistic.

Though it's certainly complicated and definitely not cheap, people with the resources to design and build a solar-power home from scratch have some advantages when it comes to flexibility. A lot of subtleties come into play when planning a residential solar system for a specific existing house. The actual design of the house is one such factor. How big is the roof's surface (which affects its potential solar surface area)? What direction does the roof face, and what's the degree of its pitch? Are there obstructions that cause partial shade? You can see most of these obstacles are impossible to change, but you might still be able to work with them. Location is also a factor. A house in Scandinavia, with its notoriously short days, won't fare as well as a house near the equator. The average number of sunny days matters too; if it's raining until nightfall, it doesn't particularly matter if nightfall comes late.

When you're trying to figure out how much power you can produce and how much you'll need, it's helpful to look at meteorological data for your area. It'll show you how much sunlight you can expect in any given month, based on past averages. You should have copies of your utility bills nearby, which will let you know how much power you use, and you can use this information to figure out if the system you want will make enough electricity. General guidelines recommend a setup that generates 1 kilowatt per 1,000 square feet of house. Don't let your optimism take over -- you need to ensure you can produce enough power to get you through the worst times, not the best. You'll want to literally prepare for the proverbial rainy day.

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