Atlas Solar Innovations - Solar Glossary

PVWATTS calculates electrical energy produced by a grid-connected photovoltaic (PV) system. Researchers at the National Renewable Energy Laboratory developed PVWATTS to permit non-experts to quickly obtain performance estimates for grid-connected PV systems within the United States and its territories.
In a grid-connected PV system, PV modules, wired together to form a PV array, pass DC electricity through an inverter to convert it into AC power. If the PV system AC power is greater than the owner's needs, the inverter sends the surplus to the utility grid for use by others. The utility provides AC power to the owner at night and during times when the owner's requirements exceed the capability of the PV system.

http://rredc.nrel.gov/solar/codes_algs/PVWATTS/

MY SOLAR CALCULATOR: The Solar Estimator is meant only to give you an idea of price, savings and system size. The results are based upon many assumptions and the limited data you will enter. An actual site assessment by a qualified Solar Pro will be needed to determine the actual costs and benefits of installing a solar system. Please read the results screen carefully, including the extensive list of Notes and Assumptions.

http://www.findsolar.com/index.php?page=rightforme

Greenhouse gas emissions calculators:

Greenhouse gas emissions calculators are available online from the EPA and other organizations. These interactive calculators help estimate the greenhouse gas emissions of human activities, convert carbon emissions to equivalent units, and identify and compare emissions reduction options. The calculators vary greatly in complexity, scope, and intent. A brief description of each is provided to help you choose one or more that best meets your needs

http://yosemite.epa.gov/oar/globalwarming.nsf/content/ResourceCenterToolsCalculators.html