Solar energy is an alternative to fossil fuels for providing electrical power for both homes and businesses. It may be locally produced and used at the same location as the panels, which reduces distribution costs and lessens risks in natural disasters. Alternatively, large facilities may be located in available space and the power added to the "grid" that distributes electricity.

In our area of Kentucky, the regional power production is 3.5 gigawatts (GW). It is supplied by Louisville Gas & Electric Company, now a subsidiary of a large conglomerate of power companies supplying energy to Kentucky and Virginia. This energy is derived by burning natural gas and coal for the most part, but it is supplemented with energy from hydropower using dams on the Ohio River, and from a solar farm with sheep that produces about 10 MW.

A gigawatt (GW) is 109 watts. A megawatt (MW) is 106 watts. A kilowatt (kW) is 103 watts. A watt is 1 J/s. A kilowatt-hour (kWh) is the energy of 1 kW delivered for 1 hour, that is for 3600 seconds.

1. The Sun provides approximately 1.4 kilowatts (kW) of energy adding all the light striking one square meter perpendicular to a line to the Sun above the Earth's atmosphere. If solar panels are 25% efficient in converting this optical energy to electrical energy, and if they are oriented to make maximum use of incident sunlight, how much panel area in square meters is needed to develop all of the regional power production while the Sun shines? Take the square root to find the dimension of a square site with that much area.

2. A typical single solar panel that would be installed on a home uses crystalline silicon as the material that creates the current, measures 1x2 meters, and produces 340 watts at 48 volts. How many of these panels operating at 25% efficiency would be needed to supply 15 kW that would fulfill the peak needs of a typical home and what area of the roof would they cover? This is for peak use, but typically the average power needs are about 5 kW, for a total daily use of 120 kWh.

3. If you could pump water to a height of 20 meters, say to a pond or pool up the hill from your home, how much water by volume would have to be moved to store 120 kWh energy for use over a full 24 hours. (Use the potential energy of gravity, ??? , to figure this out. )

4. The 2023 Chevy Bolt EV car has a battery with a capacity of 65 kWh that provides an estimated range of 397 km. Its efficiency is about 18.0 kWh/100 km when it is being driven. Given what you know about the physics of solar, comment on the viability of it as a sole source of power for your home and your rechargeable electric car. If you have a clever way of storing energy, mention it here too. Where does the electricity to power these come from now?

This is a plot of the solar electric output from a home that is self-sustaining with many panels and a battery backup system. It provides electrical energy to the grid when it produces more than is needed to operate the home and to charge its owner's two electric vehicles. The variations from month to month are a consequence of the number of clear days and the altitude of the Sun which change seasonally. The October 2023 data are incomplete.