While your budget may dictate how big your PV array will be, you
likely have a kWh production goal that you’d like to meet. Most
folks want to have a grid-tied PV system designed to offset most
or all of their annual electricity usage. The first step in
going solar is not sizing the PV system, but reducing your
electricity usage through conservation and efficiency measures.
Once these measures have been implemented, you’re ready to size
a PV system to offset the remaining energy usage. To determine
the PV array size needed, you’ll need to know the average daily
peak sun-hours for your location. Once you’ve determined your
annual kWh production goal and the peak sun-hour value, use an
overall system efficiency factor to calculate the required PV
array size. Let’s say we have a home near Eagle, Colorado. After
implementing energy-efficiency strategies, this home consumes an
average of 300 kWh per month. However, we would also like to use
an electric car, which will use an estimated 250 kWh per month
for chargin