6. How do the panels work? A solar
panel (module) is made up a number of solar cells. Solar cells are generally
made from thin wafers of silicon, the second most abundant substance on earth,
the same substance that makes up sand. To make the wafers, the silicon is heated
to extreme temperatures, and chemicals, usually boron and phosphorous, are
added. The addition of these chemicals makes the silicon atoms unstable (their
electrons less tightly held). When photons of sunlight hit a solar panel, some
are absorbed into the solar cells, where their energy knocks loose some of the
modified silicon's electrons. These loose electrons are forced by electric
fields in the PV panel to flow along wires that have been placed within the
cells. This flow of electrons through the wires is electricity, and will provide
power for whatever load we attach (a calculator, a light bulb, a satellite,
etc.) Because solar cells are modular, a system's size can be increased
(or decreased) over time, according to need.
7. Are there any applications for photovoltaics where I don't need
batteries? The simplest and least expensive PV systems are
designed for day use only. These systems consist of modules wired directly to a
DC appliance, with no storage device. When the sun shines on the modules, the
electricity generated is used directly by the appliance. Higher insolation
(sunshine) levels result in increased power output and greater load capacity.
And when the sun stops shining, your appliance stops working. These
simple systems are an appropriate, cost-effective option for loads operated only
during the daytime. Examples of day use systems include: Remote water
pumping with a storage tank. Operation of fans, blowers, or circulators to
distribute thermal energy during the day for solar water heating systems or
ventilation systems. Stand-alone, solar-powered appliances such as
calculators and toys. It is also possible, in a utility grid
interconnected system (see below), to do without batteries, as such a system is
essentially using the grid as its storage device
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