Solar Panels

How do solar panels work?

Solar panels use the principle of "photovoltics" -- which means light/electricity. The individual photovoltic cells in a panel are made of silicon, which is able to absorb light energy easily. The cells also have an electric field, so the energy (in the form of electrons) absorbed from sunlight can be directed into an electric current and carried away to be used immediately or stored in a battery.

To make this a reasonably efficient means of providing household electricity, however, is much more complicated. While silicon can absorb electrons from sunlight, it must be prodded into releasing them into the current. Silicon is shiny by nature and needs to be dulled so it won't reflect sunlight. There are numerous small variables, including solar panel cleaning and maintenance, which if followed, incrementally improve their energy-producing ability.

Solar panel installation

Solar panels are most typically installed on a rooftop, but can be placed anywhere that sunlight is plentiful, including on a backyard shed. In the northern hemisphere they should generally point southerly and even the degree of incline becomes a factor in how efficiently they operate.

While this can be taken into account in new construction, most existing roofs don't have the ideal exposure or incline. Solar panels can still collect energy if facing west or east, but not as efficiently and so the pay-off time increases.

On top of this, there can't be any shade. If even a portion of a solar panel is in the shade, the effectiveness of the whole panel is reduced.

When an open, treeless field is available, solar panels can be arrayed in support structures with the precise exposure and incline to be most effective.

Renewable energy limitations

In some climates it is possible to rely entirely on solar panels and reserve batteries and be completely disconnected from "The Grid" of the national electricity network. However, this is usually not feasible because most of us live in areas prone to cloudy or rainy weather.

Remaining connected to the electric utility's infrastructure has two advantages: (1) It provides a back-up source of power on cloudy, rainy days and (2) in most states you can sell your excess electricity back to the utility as a credit against your next bill.

The main drawback to electric power of any origin has historically been that it's a constant flow that has to be used or lost. That's why electric companies have to manage for their peak usage times because any time the peak demand exceeds the flow there will be outages. Meanwhile, when demand is less, excess power being generated goes to waste. Battery storage, at least until recently, has not been efficient enough to take advantage of the excess.

The same is true of solar houses off the grid. On sunny days, you make more power than you need. To some extent, you can save some of the energy in batteries to be used later, but generally speaking you lose most of the energy being produced that exceeds your need at that moment.

When a solar house is connected to the utility grid, this excess solar energy can be fed backwards to the utility and credited to the homeowner's next bill. The electric meter can actually go backwards.

You'd think that one of the advantages of this combination would be that your house would have solar power to fall back on during utility outage -- while the rest of the neighborhood does not. This isn't necessarily the case because of a safety feature that shuts down your solar-generated electric current during a utility outage. This is done to ensure that utility electricians working on restoring the power are not jolted by the reverse-flow of energy coming back along an otherwise dead line.

To get around this problem, you can have an additional switch installed in your system that makes your system independent of the utility when you need it to be. This, of course, adds to your investment cost.

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