Have you ever wondered if it is practical to consider powering your house with solar electricity? Well, in a recent article at How Stuff Works they asked the question "How many solar cells would I need in order to provide all of the electricity that my house needs?"
Making a series of assumptions about electricity use and basing the hardware costs on today's rates, the writers concluded that it would cost at least $30,000 to generate enough to provide the electrical requirements of a typical home. And that doesn't even include the cost of space heating, water heating, cooking, and clothes drying - all of which it was assumed would be done by natural gas.
The numbers go like this. A "typical" home in the US requires an average of 600 watts per hour every 24 hours to run the lights, appliances, computers, refrigerators, TVs, and fans and motors on other appliances such as the furnace, clothes washer and dryer, and so on. That is approximately 14,400 watt-hours per day.
To generate that much electricity using solar cells you would need about 41,000 square inches or 285 sq. ft. of solar panels. At today's prices that would come to about $16,000. And then, because the sun is not available for parts of some days or at all on other days you would need a battery storage system that would cost at least the same - roughly another $16,000. So that puts the price at about $32,000 for the system.
At today's cost of electricity off the grid that much electricity would cost roughly $525 per year. At these rates, to recover the up-front costs would take more than 50 years. Long before that time had passed the entire system would have to be replaced. In fact with today's technology the battery system would probably have to be replaced several times over that time period. So it is no wonder that not very many "solar houses" are being built.
Even if we accept these numbers at face value it does not mean that solar energy has no place in the energy mix of the future. It just means that it is important to think long and hard about where it is practical to use it.