Residential – Appendix – What does all this mean?
What is a Watt?
The power capacity of a PV panel is rated in watts.
A typical PV panel has a power capacity between 130 and 230 watts and has varying size options.
When many panels are linked together to form an array, the power capacity is often referred to in units of kilowatts (kW) or 1,000 watts.
1 kW of optimally oriented PV will generate an average of 1,500 kilowatt-hours (kWh) of electricity per year.
For reference, a 1 kW system under good sunlight has enough instantaneous power to run ten 100-watt light bulbs, or forty 25-watt compact florescent (CFL) bulbs.

What Makes a PV System?

A PV system includes panels, racking, inverters, wiring, and conduit. Batteries and charge controllers are required only if back up power is needed.  Many people rely on the grid for this.
Typical panel efficiency for converting sunlight to usable power for your home is 13%–18%.
Panels are warranted for 20 to 25 years, inverters for 10 to 15 years.
Panels are designed to withstand hail, snow, and wind without incurring damage.
System racking is designed to meet the wind zone ratings of specific neighborhoods.

A Straight Grid-Tied Solar Electric System:

Has no batteries.
The PV system will shut down when a utility electrical outage occurs. This prevents electricity that is being generated by the system from back-feeding the grid and neighborhood lines, which could possibly electrocute a line worker.
Can be sized to cover over 100% of your annual electric needs.
Is interconnected with the grid so you will always have power, even at night or on overcast days.
Allows you to spin your meter backwards. You will be credited at the retail rate for any power your system feeds onto the grid.

A Typical 4 kW System:

Although designing a PV system is entirely custom, a 4 kW system will power an average sized residential home.
Your home’s solar energy system will produce electricity for over 30 years.
Impact of a 4 kW Array:
Reduces CO2 emission by 11,580 lbs per year.
Will save you $700 on utilities in the first year and over $31,000 during a typical 25 year lifetime of a system (assuming we continue to see a 5% annual escalation in utility rates).
Takes up about 350 ft2 of roof space, depending on panel capacity.
Did You Know?
Solar energy can save you hundreds of dollars on your electric utility bills and dramatically increase the value of your home.