Confused about all the technical terms used in the solar industry? From electrical concepts and units to solar-specific jargon, we’ve translated the technobabble to easier-to-understand definitions.
Understanding electricity
Think of electricity moving through a wire like water moving through a pipe. The pressure that the water is being pumped with is the voltage of the electricity. Voltage is measured in volts – a small amount can be expressed in millivolts and a large amount in kilovolts.
In North America, our electrical system- or grid– provides 240 volts of electricity through a system of wires and substations, into your wall outlets and eventually into whatever you plug in.
In this analogy, the current of the electricity would be a measurement of the flow rate of water at any given time. Current is measured in amperes– or amps for short.
Resistance can be thought of as the size of the pipe, which limits the flow of the water. It is measured in Ohms.
A watt is a unit of power. It’s the measurement of the amount of work that a circuit can do given the voltage and current that the electricity is flowing with. In our analogy, it would be the ability to turn a wheel with the water coming out of the pipe.
On your electricity bill, you’ll see that you’re being charged by the kilowatt-hour– or kWH- which is just a measurement of the total amount of power that you have used. A kilowatt-hour is equal to one kilowatt of power sustained for one hour.
Alternating current (AC) and Direct Current (DC) are different ways that electricity can be moved through a wire. Either the electrons flow in one direction (DC) or they flow back and forth (AC).
An inverter can convert DC power into AC power and a rectifier does the opposite. An example of an everyday rectifier is the little block on your laptop’s charging cable.
The grid refers to the system that delivers electricity from the powerplant to your home. It’s very technically complex, but for our purposes, electricity is generated, it’s transported at high voltages and then “stepped down” at substations along the way to your outlet.
Your solar system
A residential solar system uses solar panels to harness the power of the sun via a technology called photovoltaics. The power it generates is DC power, which must be inverted to AC power to be used in the home or go back onto the grid.
If the energy is going into a battery, it can also travel directly to the battery and then be inverted to AC power before heading into your home.
The amount of electricity that your system can generate is the system capacity and is measured in kilowatts. It is usually just the total number of panels multiplied by their individual wattage.
If you divide the amount of energy your system produces by the amount that your home used over the same period of time, you get your solar offset. It represents the percentage of energy you usually pay for that would be offset by solar energy.
This number can be very accurately estimated and is important to consider when planning to go solar.
Solar systems can also be grid-tied, off-grid or a hybrid of both. Grid-tied systems connect your system directly into your house and the grid to directly offset power from your utility and take advantage of any energy credit or net metering program.
Off-grid systems are not connected to the grid and instead use solar-charged batteries to power the home. These allow a property that doesn’t have grid access to have electricity, but require a lot of panels and large batteries.
A hybrid system is like a grid-tied system, but it introduces battery to the mix as well. The batteries in these systems are used for back-up in case of an outage or to power the home when the panels can’t produce electricity.
Understanding solar batteries
Batteries are used to store up excess electricity for use when solar panels aren’t actively generating electricity. Their storage capacity is measured in kilowatt-hours.
Output values describe the electricity a battery can pump out either into your home or onto the grid.
The peak output values define what a battery can safely output during a surge. Manufacturers measure these values over different time periods, sometimes as short as a couple seconds all the way up to a couple minutes.
Continuous output values are the current, voltage and wattage that are discharged under the normal operation of the battery.
