Solar energy is an alternative to fossil fuels for providingelectrical power for both homes and businesses. It may be locallyproduced and used at the same location as the panels, which reducesdistribution costs. Large facilities may be located in availablespace and the power added to the \"grid\" that distributeselectricity. Solar power may be a better choice in rural orundeveloped areas where the grid infrastructure is unreliable orjust not there, and it has been discussed as an alternative forreconstruction in storm-damaged Puerto Rico. It is also useful inless sunny areas, and here in Kentucky the regional power provideris developing a shared solar energy farm to supplement itsconventional power plants. Even the Coal Museum in eastern Kentuckyhas solar panels to provide building power. 1. The Sun providesapproximately 1.4 kilowatts (kW) of energy adding all the lightstriking one square meter perpendicular to a line to the Sun abovethe Earth's atmosphere. If solar panels are 25% efficient inconverting this optical energy to electrical energy, and if theyare oriented to make maximum use of incident sunlight, how muchpanel area is needed to develop 10% of the regional powerproduction which is 3.5 gigawatts (GW) while the Sun shines? (3.5GW is 3,500 MW. Currently LG&E has a 10 MW solar farm covering50 acres.) 2. A typical single solar panel that would be installedon a home uses crystalline silicon as the material that creates thecurrent, measures 1x2 meters, and produces 340 watts at 48 volts.It is said to be 17% efficient, allowing that not all the sunlightat the top of the atmosphere reaches the surface, and that somewavelengths are beyond the range over which silicon responds. Howmany of these panels would be needed to supply 15 kW that wouldfulfill the peak needs of a typical home? What area of the roofwould they cover? This is for peak use, but typically the averagepower needs are about 5 kW. 3. If it is sunny 8 hours a day, thenyou would need 3X as many panels and a way to store energy to usethem 24/7, but storage also allows you have fewer panels to meetpeak needs. Allowing that the panels gather enough energy during 8hours to provide power for that time and for 16 more hours, howmuch energy has to be stored? Consider two alternatives: pumpedwater and Tesla batteries. If you could pump water to a height of20 meters, say to a pond or pool up the hill from your home, howmuch water by volume would have to be moved to store this energy .(Use the potential energy of gravity, mgh, to figure this out. )For batteries, consider the Tesla \"Powerwall\", a module that stores13.5 kWh of energy and provides 7 kW peak AC power. 4. Given whatyou know about the physics of solar, comment on the viability of itas a sole source of power for your home, and your rechargeableelectric car. If you have a clever way of storing energy, mentionit here too.
