Solar glossary

The terms you will hear, explained simply.

Anti-islanding: A safety feature of grid-tied inverters. They stop supplying power when the grid is down, so they do not energise a line that utility workers may be repairing.
Battery capacity (kWh): How much energy a battery can store. Only part of it is usable, because batteries should not be fully drained.
Brownout: A loss of utility power. In everyday use in the Philippines it often means any power outage.
DC and AC: Solar panels produce direct current (DC). Homes use alternating current (AC). The inverter converts one to the other.
Depth of discharge: The share of a battery's capacity that is used before recharging. A higher usable depth of discharge means more of the battery's capacity is available to you.
Grid-tied (on-grid) system: A solar system connected to the utility grid, usually without batteries. It lowers your bill but shuts off in an outage.
Hybrid inverter: An inverter that manages solar panels, a battery and the grid together, and can supply selected circuits when the grid is down.
Inverter: The device that converts the DC electricity from solar panels into AC electricity that your appliances use.
kW (kilowatt): A measure of power: how quickly energy is being used or produced at a moment in time. 1 kW = 1,000 watts.
kWh (kilowatt-hour): A measure of energy: using 1 kW for one hour. This is the unit on your electricity bill.
kWp (kilowatt-peak): The rated capacity of solar panels under standard test conditions. It is the usual way to describe the size of a solar system.
Load: Anything that uses electricity, such as lights, fans, a refrigerator or an air conditioner. Your total load decides inverter and battery sizing.
Net metering: An arrangement under which surplus solar energy sent to the grid can be credited. The rules, eligibility and crediting depend on the utility and current regulations, so confirm them for your situation.
Ocular inspection: A site visit to look at your roof, electrical panel and surroundings before a solar proposal is prepared.
Off-grid system: A standalone system with solar panels and batteries that is not connected to the utility grid.
Peak sun hours: A way of expressing how much usable sunlight a location gets in a day, as the equivalent number of hours of full-strength sun.
Surge (starting) power: The brief extra power that motors, such as refrigerators, pumps and air conditioners, draw when they start. Inverters must be sized to handle it.
System performance factor: An allowance for real-world losses in wiring, the inverter, heat and dirt, so a system produces less than its rated capacity suggests.