Solar Panel Calculators – What You Should Know

A Private Company Solar Calculator

Homeowners should be wary when using solar panel calculators that request your contact information. The only personal information you need to provide is your address, so be cautious of sites which ask for your name, phone number or email. It’s unnecessary to provide this information in order to get an accurate estimate of your home’s power production and solar power savings potential. In general, this is more likely to occur with a calculator on a private company’s site.

A Utility Company Solar Calculator

Some utilities have solar power calculators, however depending on the utility, their information and data may not give you the most accurate, up to date estimate for your home. Also, most utilities require that you are a current customer in order to use these calculators.

A Federal or State Agency Solar Calculator

National and state government solar power calculators are reliable resources for homeowners and can be trusted to give you the most accurate estimates for power production potential and expected savings for your home. If you’re just looking to see what energy potential your home has, how much you could save in energy costs and how many solar panels to power a house, we recommend using the PVWatts calculator. which was created by the National Renewable Energy Laboratory (NREL) – part of the Department of Energy.

Follow this tutorial as we walk-through NREL’s PVWatts calculator which will show you an accurate estimate of the amount of energy you can produce with solar on your home and the savings you can expect from a home solar system. After entering your address, the PVWatts solar PV calculator uses local weather tower data to assess the amount of sunlight received in the area. This dramatically increases the accuracy of the estimate, which helps you get a great idea of the savings and potential energy production with solar on your home. The PVWatts calculator is a great choice for homeowners due to its simplicity and reliability.

To see what kind of power production potential your home has, enter your address where it says “get started” and click go.

After clicking go, the solar power system calculator will determine the closest weather tower to you, which tracks the area’s weather data. This will determine the amount of sunlight your home receives yearly and will help determine the performance potential of a solar panel system throughout the year. Next, click the orange arrow on the right that says “go to system info”.

The top section of this page guides you through the sizing of your potential solar system. The numbers below are the default settings on a standard PV system of 4 kW. If you decide to use these default numbers, you will still be able to get a reasonable estimate for solar power. They also provide you with the option to draw your potential system size on your roof for a more specific estimate.

Next, scroll down the page to the “initial economics” section. If you know how much you pay on average for your electricity per kilowatt hour, you can fill that information in. If not, you can keep the default average cost. The initial cost does not need to be changed for your estimate – this is a standard number used.

Below that on the system information page, is a section with available incentives and rebates for your area. The programs listed may not include incentives available from your utility company. You can select as many incentives as you would like. If you’re unsure, you can check all of the incentives and rebates – this will give you the lowest estimate for the cost of solar on your home.

Please note that while the PVWatts calculator says the incentives haven’t been updated by the Database of State Incentives for Renewable Energy since 2013, the DSIRE site has in fact been recently updated. After you’ve selected all of the available rebates, click the orange arrow on the right that says “go to PVWatts results”.

This final page of the calculator shows you the results of the calculations for your property. The bold number across the top shows an estimate of how much energy you could be producing each year with a solar panel installation on your house. Then, the chart breaks the findings down into three main columns – the solar radiation of your home, the AC energy and the energy value.

The solar radiation is determined from the weather tower data. Essentially this shows you how much energy the sun is shining on your home on average over the year.

The AC energy is the amount of electricity in kilowatt hours your potential solar energy system could be generating month to month. In the example below, the potential solar system could be generating around 6,443 kWh of energy per year. This number will vary depending on the size of the solar panel system and location.

The last column is the energy value – the amount you could be saving each year by switching to solar. They calculate this number by multiplying the number from the AC energy column by the average cost of electricity.