How to Use Free Government Software to Calculate Your Possible Solar Savings

Have you ever wondered how much energy you could save or money you could make by putting a solar photovoltaic PV system on the roof of your home ,cottage or business? Well if you live in the United States you are in luck. The department of energy has created a really easy to use tool for you and its free. My favorite kind. It is called the PVWatts calulator.

The PVWatts calculator was developed by NREL’s Electricity, Resources, and Building Systems Integration Center and is available over the internet for free,

The program is an Internet-accessible simulation tool for providing quick estimates of the electrical energy produced by a grid-connected crystalline silicon photovoltaic (PV) system for any of 239 locations.

These locations correspond to the 239-station Typical Meteorological Year (TMY2) database for the United States and its territories. Users select a location from a station map and set PV system parameters, or select default values, and PVWATTS performs an hour-by-hour simulation that provides monthly and annual alternating current (AC) energy production in kilowatts and energy value in dollars. System parameters that may be specified include size (AC rating for Standard Reporting Conditions), local electric costs, PV array type (fixed or tracking), PV array tilt angle, and PV array azimuth angle.

The performance model used by PVWATTS is based on Sandia National Laboratories’ PVFORM, but with fewer allowed specified inputs. NREL’s PVWattsTM calculator determines the energy production and cost savings of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, installers, manufacturers, and researchers to easily develop estimates of the performance of hypothetical PV installations.

The PVWatts calculator works by creating hour-by-hour performance simulations that provide estimated monthly and annual energy production in kilowatts and energy value. Users can select a location and choose to use default values or their own system parameters for size, electric cost, array type, tilt angle, and azimuth angle. In addition, the PVWatts calculator can provide hourly performance data for the selected location.

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.

The PVWatts calculator is available in two versions. Site Specific Data Calculator (Version 1) allows users to select a location from a map or text list of pre-determined locations throughout the world.

Grid Data Calculator (Version 2) allows users to select any location in the United States.

Tags: “solar career”, crystalline silicon, default values, electrical energy, energy production, energy systems, energy value, kilowatts, performance model, performance simulations, pv installations, pvwatts, sandia national laboratories, simulation tool, solar photovoltaic, system parameters, systems integration center

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