A PV System in Your Building
A properly designed photovoltaic (solar electric) system will work, and work well, for years. But you as the builder, and your customer, the homeowner, shouldn’t expect more of the system than it can provide. Whatever system is chosen, even the simplest will need homeowner maintenance.
To generate The generation of green electrons today, at this stage of PV market maturity, needs homeowner involvement. The amount of involvement depends on the homeowner, and can range from simply keeping things clean, to complete immersion and being known as the “nerd of green.”
The simplest system is the “grid-intertie.” This is a PV array (an array is simply a bunch of PV modules connected together) that generates direct current of, let us assume, 1,000 watts. Because it is DC, the normal household needs to change it to AC before household appliances can use it. This is done with an inverter, and it is simply tied to the power company. Any power your system generates is used by the loads of your house first. If you aren’t using the full output of your array, the excess power is fed into the grid system of the power company.
Each local power company has its own way of “buying” your excess power, ranging from letting your meter “run backward,” or “net metering” (that uses two meters, one showing how much you’ve used of the power company’s power, and how much your system has pumped into the power company’s system—with the difference between the two used to figure your bill), or using the second meter to figure how much your system has pumped into the grid, but paying you for that at a rate different than what you pay for the power company’s energy.
One kilowatt (also expressed as 1,000 watts or 1 kW) is probably the smallest system that economically should be installed. Multiples of 1 kW are easily added, normally to about 5 kW for single family residences.
This simple grid intertie system needs only occasional maintenance in the form of washing off the PV modules. Normally Mother Nature’s rainfall will keep them clean. The homeowner may also have to look at the inverter’s panel to see if there are red lights or other signals telling if the inverter may not be working. Those signs may trigger a call to your friendly PV technician.
Falling leaves need to be kept off the array. Any blockage wipes out a PV cell’s ability to generate electricity—and is the enemy of generating green electrons!
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