To determine which is the best solar energy calculator to use, you first need to figure out what kind of information you’re looking for.
Some solar panel calculators focus on calculating solar energy production data, while others are focused on the financial aspects of going solar. The latter is sometimes referred to as a ‘solar payback calculator’.
There are two leading independent solar energy calculators available to US consumers and solar installers who wish to do their own solar calculations.
The first solar calculator is PV Watts from NREL (National Renewable Energy Laboratories). This solar calculator is known for its ability to forecast energy production for a specific array of solar panels on a specific roof, in a specific location. In fact, its energy production data is used by many other solar calculators, including www.solar-estimate.org's.
However, the limitation of the PV Watts calculator is that you have to know a solar system’s precise size. Based on the information from your power bill, it cannot tell you the size of the system you are likely to need. The PV Watts calculator also requires you to know how much you pay for electricity, whereas the Solar-Estimate solar calculator is linked to the pricing schedules of every utility in the US. That means, once you enter the name of your utility and average monthly bill, the Solar-Estimate calculator determine how much power you are using and what size system you would need to cover that power usage.
The benefit of the PV Watts calculator is that it shows energy production for each month of the year. You can also use this tool without having to enter your name or any contact information. The PV Watts solar calculator is often used by installers so they can generate a graph of solar production over each month of the year, once the installer has worked out what size solar system they wish to quote a client.
The advantage of the Solar-Estimate calculator is that it uses the same PV watts solar irradiation and production data - however, it is linked to the pricing tables of each utility as well as live pricing data provided by 200 solar installers throughout the US. This means that the Solar-Estimate calculator only requires you to know the name of your utility and the amount of your average power bill. With that information, the Solar-Estimate calculator can tell you what size system you need and how much it will cost. With the PV Watts calculator, you need to input all of this information yourself.
The perceived disadvantage of the Solar-Estimate calculator is that you must be prepared to be contacted by a solar company. With that being the case, we suggest using the PV Watts calculator if you are just looking for production data. If you’re seeking more detailed financial intelligence and are at the stage where you want an estimate that will be confirmed with exact live pricing, then you are better off using the Solar-Estimate calculator.