How to Plan a Solar System
Residential solar power is one of the most sought after alternatives
for home energy needs. Apart from scaling down your utility bills, solar is a renewable source that helps to
minimise on the carbon footprint.
Like most worthwhile projects, good initial planning will ensure that you get the best value for your solar
1. Assess the potential solar radiation capacity
If you’re considering installing a solar electric system, the first thing you need to do is to determine the
amount of energy that can be absorbed when the panels are installed, based on your area’s average daily solar
radiation. The National Renewable Energy Laboratory (NREL) resource assessment program releases a map on which you
can reference average values for different areas.
Most parts in the US can achieve up to 5kWh per square meter per day. Some areas can achieve up to 8kWh per
square meter. In the delineation kWh/square meter, kWh represents the unit of electricity called kilowatt hour,
while square meter stands for surface area of the absorbing surface. Photovoltaic panels work at efficiencies of
about 7 to 17 percent, on average.
2. Estimate your average energy consumption
Once you’ve determine how much radiation your residence can absorb from the sun, the next thing is to determine
your household energy usage, based on monthly consumption. The simplest thing to do is to request your previous
year’s statement from your utility.
You can also use standardized state-by-state averages, made available by the Energy Information Administration.
For instance, according to their information, a resident of New Jersey can consume 730kWh per month, while one in
Alabama can use up to 1300kWh each month.
3. Determine the number of photovoltaic panels needed
Now that you know how much solar power can be utilized, it’s time to calculate how many photovoltaic panels you
will need to generate the amount that your home consumes. This entails determining the exact size of every cell in
square meters, which information can be obtained from a manufacturer.
For instance, if a residence has an average monthly usage of 1000kWh, 5kWh/square meter of solar radiation per
day, and panel efficiency of 7 percent, to estimate the number of panels needed to produce 1000kWh every month
(30.42 days on average), the equation for calculating number of panels needed would be:
5 (radiation) * 2 (surface area of standard panel) * 0.07 (solar efficiency) * 30.42 = 21.294kWh
per panel per month.
Then to cover 1000kWh usage, we divide 1000/21.294 = 47, meaning you would need 47 solar panels (of standard
size 2 square meters) to generate that amount.
4. Estimate initial costs and long-term savings
For most homeowners, the initial installation costs for a solar electric system is a major factor. However, with
the potential annual savings, coupled with government incentives and rebates, it is worth the initial investment.
On top of that, it is also possible to selling solar power
to utility companies.
The size of the system you install will determine much of the costs. With 42 states, including DC, required by
government to buy surplus power from consumers, the initial costs can be quickly paid for. The rates you could
receive for your surplus differ by state.
5. Plan the installation
A solar contractor will determine suitable panel orientation for the different seasons, using your area’s
latitude. For maximum absorption of solar radiation, panels are mounted at the same angle as the latitude.