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Solar Electricity (Photovoltaic)
During construction, the solar water heating panels were positioned to leave space so that solar electric (photovoltiac) modules could be installed in the future. Another element of the PV-ready plan was to anticipate a place to mount the inverter. It's generally best to locate the inverter next to the electric service panel (breaker box). It's also important to eliminate any obstructions on the roof that would interfere with the placement of PV modules. In this case, one or two plumbing vents were moved to the north slope of the roof. Other possible obstructions might be chimneys, flues, dormers , roof vents, etc.
In late 2009, a combination of falling PV prices and generous financial incentives combined to make the cost of PV so attractive that it was impossible to refuse.
With a system capacity of 2 kiloWatts, the PV system should produce about 2600 to 2800 kiloWattt-hours each year. That's almost one-third of the toal energy consumed in the home, because of the many conservation features installed for space heating, water heating, appliances, etc.
Horizontal rails are attached firmly to the rafters with lag bolts. Measure carefully to hit solid wood.
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A plate slips under the shingle above to shed water over the bracket. PV modules will be attached to the rail - held securely against the wind. Space below the modules allows air movement that cools the modules and improves performance in hot weather.
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Electric connections (direct current) are made from juntion boxes on the back sides of the panels.
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The PV array sites nicely next to the solar water heating panels.
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The PV Powered 2000 inverter accepts direct current from the PV array and changes it into alternating current for use in the home and for export to the electric utility grid. The inverter contains safety features that shut down the array if the grid goes down. Electricity is used first by lights and appliances in the home. If there is more power available than the house can use, the power flows to the electric utility wires, where it is likely consumed in neighboring homes. The kWh meter (center) measures the total electricity generated by the PV system. A special "net billing" meter on the outside of the house keeps track of how much electricity is consumed by the house and how much is sold to the utility. Each monthly utility bill shows the amount purchased and how much is sold.
