How to Calculate Potential Solar Power Generation For Your Property
Our sun is an endless source of energy – and solar power technology continues to get better and cheaper every year. Meanwhile, electric utility rates are continuing to rise. More and more people are looking to onsite renewable energy systems as a way to hedge against the ongoing trend of rising electric utility rates. You might be one of them.
But how much solar power would you be able to theoretically generate on your property? How much money could you save?
The National Renewable Energy Laboratory has created a handy online calculator which they call the PVWatts™ calculator. It allows you to generate estimates of the performance of a hypothetical PV installation on your property.
According to NREL’s website, “The PVWatts calculator works by creating hour-by-hour performance simulations that provide estimated monthly and annual energy production in kilowatts and energy use… Using typical meteorological year weather data for the selected location, the PVWatts calculator determines the solar radiation incident of the PV array and the PV cell temperature for each hour of the year. The DC energy for each hour is calculated from the PV system DC rating and the incident solar radiation and then corrected for the PV cell temperature. The AC energy for each hour is calculated by multiplying the DC energy by the overall DC-to-AC derate factor and adjusting for inverter efficiency as a function of load. Hourly values of AC energy are then summed to calculate monthly and annual AC energy production.”
There are two versions of the PVWatts calculator.
Version 1 is a site-specific data calculator. It allows users to select a location from a map or text list of pre-determined locations throughout the world.
Version 2 is a grid data calculator, which allows users to select any location in the United States.
By following the onscreen instructions and entering in all the relevant data, your results will look something like this:
Green Leaf Inn’s results
The Green Leaf Inn (GLI) is on its way to becoming North America’s first net-zero energy hotel. In order to accomplish this goal, GLI is working with Community Green Energy (CGE), a company that develops and finances renewable energy and energy efficiency projects nationwide. Through the development of Power Purchase Agreements, CGE is helping to make the implementation of multiple sources of alternative energy at the GLI economically feasible.
The 19-suite luxury inn is planning on installing a grid-tied, ground-mounted solar PV system with a DC rating of 20.0 kW. According to the PVWatts calculator, the inn’s proposed system would generate 23,086 kilowatt hours of AC electricity (enough electricity to power two average-sized homes), earning a credit of $4155.48 dollars over the course of 12 months.
Achieving Net Zero
The Solar PV system won’t be the only source of power generation at the Green Leaf Inn. In fact, there will be 7 energy systems on the premises, all working together. These state-of-the-art systems will work in concert to make sure the Green Leaf Inn is able to produce as much electricity as it uses over the course of a year.
The PVWatts calculator is only a preliminary tool.
While the PVWatts calculator isn’t intended to be used to determine whether a solar PV system on your property would be feasible, it’s a good place to start. However, be aware that the calculator cannot account for possible obstructions on your property, such as excessive shade from trees or buildings. Remember, the results given are purely hypothetical.
With that in mind, for the most precise assessment possible, you will need an energy consultant as well as a thorough solar feasibility study. If interested, Community Green Energy would be a good place to start. CGE projects include community solar gardens, Virtual Solar PPAs, Community Choice Aggregation for sustainable communities, RECs, and energy performance contracting.