What doesn't move, however, is a suspended mass inside the seismograph, called the seismometer. During an earthquake, the seismometer remains still while the case around it moves with the ground shaking. Traditionally, the suspended mass was a pendulum, but most modern seismometers work electromagnetically.
Solar electricity costs about $10 to $12 a watt installed, though you may be eligible for state incentives. Check your utility bill to see your monthly usage. A robust solar electric system will cost about $20,000. You can spend as much money, to receive as much solar electricity, as you feel comfortable with.
A bright idea gets cheaper. Since 2007, the cost to buy a solar power system has fallen by about 50%, to an average upfront cost of $4,590 per kilowatt, says the Solar Energy Industries Association (a typical home system ranges from 3 kW to 7 kW). You would recoup your upfront cost in an average of seven to 15 years, the Solar Foundation reports.