Off-grid PV systems have traditionally used rechargeable batteries to store excess electricity. With grid-tied systems, excess electricity can be sent to the transmission grid, while standard grid electricity can be used to meet shortfalls. Net metering programs give household systems a credit for any electricity they deliver to the grid. This is handled by 'rolling back' the meter whenever the home produces more electricity than it consumes. If the net electricity use is below zero, the utility then rolls over the kilowatt hour credit to the next month. Other approaches involve the use of two meters, to measure electricity consumed vs. electricity produced. This is less common due to the increased installation cost of the second meter. Most standard meters accurately measure in both directions, making a second meter unnecessary. COUNT 5
QSN1 Where do off-grid PV systems store excess electricity? ANS1 rechargeable batteries QSN2 What do off-grid PV systems use to store excess electricity? ANS2 rechargeable batteries QSN3 What are the programs that gives credit to households for delivering electricity to the grid called? ANS3 Net metering programs QSN4 How is the credit to households accomplished? ANS4 by 'rolling back' the meter whenever the home produces more electricity than it consumes QSN5 Why is a second meter usually unnecessary to monitor electricity use? ANS5 Most standard meters accurately measure in both directions