Photovoltaic FAQ's
Photovoltaic (PV) Installations
Q: What’s the size and weight of a PV panel?
A: They vary, but most are around 3′x 6′ and weigh about 40lbs.
Q: How many panels are normally required?
A: For reasons of cost-effectiveness, most installations comprise at least twelve panels.
Q: How should panels be positioned on rooftops?
A: The ideal roof slope is 35° (7/12). The panels should be angled a little west of south (194° or further west), to avoid morning haze and to better accommodate the generally more prevalent use of power later in the day.
Q: Might installation and use increase roof leaks?
A: It’s unlikely, since arrays are bolted to rafters, not plywood, and flashing and caulking is done at time of installation.
Q: Wouldn’t the array interfere with roof maintenance or replacement?
A: If roof shingles are over ten years old, it would be sensible to re-shingle before the installation.
Q: Will my roof need reinforcement?
A: Roofs must be appropriately up to code for weight bearing, but should not need reinforcing.
Q: What kind of maintenance do the panels need?
A: None.
Q: What is the life expectancy of a solar panel?
A: It’s in the 35-40-year range, usually with a 20-year warranty.
Q: When panels wear out, do they die a slow or a sudden death?
A: A solar panel is effectively productive until the end of its life. As a disclaimer, GE reports a loss of .05%/year on their panels, but in practice, when a panel has reached the end of its lifespan of 35-40 years, energy production ceases.
Q: What other equipment will need to be installed?
A: An inverter will be placed next to your existing electricity panel to convert the DC power from the array to 220VAC. Your existing panel must have approximately 30 amps open to accommodate the solar array, or an additional subpanel will need to be added. The power cable can be run through the house or outside, as best suits the installation. Also, assuming you will be connected to the grid, the installer will replace your existing meter with a ‘net’ meter. An additional meter that will read the power output of the solar array will be installed between the inverter and your electrical box.
Q: How does my power generation show up on my bills?
A: When you are providing less than 100% of your electrical usage through your panels, you will be billed by your Electric Company for the remainder of the power you use. With your panels in place and functioning, you will see a marked decrease in your electrical bills.
When your usage is so low that you are feeding power back into the system, it is held as a credit against your heavier consumption on a month-to-month basis. Since there’s no ‘roll-over’ from month to month, you won’t accrue large negative balances owed to you by the Electric Company.
