How Solar Power Works

Here is a simple explanation of how solar power works. It all starts 93 million miles in space with solar radiation from the sun.

1. Photons from the sun are absorbed by your photovoltaic panel(s). The PV module converts the solar power into direct current (DC) electrical energy. This conversion process is not perfectly efficient. In fact, only 10 to 20% of the energy absorbed is turned into electricity.

2. The DC electrical energy travels over thick copper cables into your charge controller. The charge controller is responsible for keeping the current and voltage going to your battery at just the right levels. Batteries are sensitive creatures and must be treated with care for long life and good performance. If the energy is needed right away then the controller routes the energy to the inverter which converts into alternating current (AC) which power lights and appliances in your home.

3. When the energy from your PV modules isn’t sufficient to power your loads, the controller routes stored energy from the battery through the inverter to give you the AC you need.

There are variations on this process. For example, a grid-tie only system does not have any batteries or charge controller. The electricity goes directly from from the PV modules into the a special kind of inverter. The grid-tie inverter synchronizes with and feeds the AC back into the power grid.

Battery-less Solar Power Systems

For a grid tie system, the power company grid is essentially your “battery.” The price of any energy your not using as it’s generated is credited to you at the rate in effect when generated. Your a billed for the energy at the going rate at time you use it.

So if you generate electricity during the hot afternoon and sell it to the grid at a higher price then use electricity at night at a lower price, then you actually make money. Provided, of course, that you use as much or less energy than you generate.

Net Metering

This process of accounting for energy your grid-tie solar electric system produces is known as net-metering and is available in most U.S. states. Net-metered grid tie is environmentally sound and can be economically feasible if you can generate a surplus of energy.

Complexity vs. Independence

Without charge controllers and batteries your system will be less expensive and require less maintenance and attention to its operation.The disadvantage is the that battery-less grid tie systems are only as reliable as the grid itself. If the grid fails, then you’re stuck without power just like everyone else. So it fails the personal energy independence test.

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