Our solar energy glossary; our guide to solar PV systems, battery storage, and electricity
When you’re looking for a solar PV system for your home, you’ll come across a range of solar energy terms related to electricity, residential solar PV systems and battery storage. We’ve created this solar glossary to help you make sense of your solar power options.
This is a three-part solar glossary to cover electricity related terms, solar specific terms and then battery storage terms.
Jump to Solar Glossary
Jump to Battery Storage Glossary
Electricity Terms
Alternating current (AC)
Alternating current is an electrical current that is used to power most of your appliances, chargers, lights and anything you plug into your power points at home in Australia.
With a solar PV system, the inverter changes direct current electricity (see direct current or ‘DC electricity’) into alternating current electricity to use in your home.
Baseload
Your baseload power or baseload demand is the lowest amount of electricity you use at home at any point in time, and is usually measured over a 24-hour period. If you have an advanced meter you can use your interval data that shows your electricity usage in My Account to look at your electricity use and get an idea of your baseload power when your usage is at its lowest over a given period.
Learning about the way you use electricity at home, including your baseload power, is a great first step when you’re working out what size solar PV system may suit your needs.
Demand
In the electricity industry, demand refers to how much electricity is needed at a particular time. For example, there is generally a high demand for electricity across the energy system on hot days in summer when many people use air conditioning, compared to cooler summer days.
Direct current (DC electricity)
Direct current (or DC electricity) is an electrical current which flows in just one direction. If you have a solar PV system at home, your system will generate DC electricity and send this to the inverter to be turned into alternating current electricity to power things in your home like your lights and appliances.
Electricity units
Electricity is the movement of electrons and often measured in watts (W), kilowatts (kW) and kilowatt-hours (kWh) – there’s more on these below. A ‘unit’ of electricity is one kilowatt-hour (kWh). The price you pay for electricity includes an electricity charge for how many units of electricity you have used from the energy system.
Energy efficiency
The higher the energy efficiency rating something has, the more efficient it is. For example, a washing machine with a high energy efficiency star-rating will use less energy per wash than a lower efficiency model of the same size (with the same kind of wash settings).
Grid
When you’re exploring solar power, you’ll often find references to electricity from “the grid”, electricity network or energy system. This refers to the connected network of electricity infrastructure including the generators, and the transmission and distribution lines that transport electricity to homes, businesses and other grid-connected consumers. If you’re a Synergy customer, the grid is known as the SWIS – or the South West Interconnected System. Even with a solar PV system, you’ll need to draw on electricity from the energy system when your system isn’t generating enough electricity to meet your demand.
Irradiance
This is a measure of solar energy or light energy from the sun on the Earth at a point in time. Solar irradiance is generally highest when the sun is shining during the middle of the day, compared with early morning and late afternoon sunshine.
Kilowatt (kW)
A kilowatt is a measure of power that is 1,000 watts. You might have a 1kW appliance. Whether you use this for a minute or an hour or more, it will still need 1,000 watts (or 1kW) of power to function.
Kilowatt-Hour (kWh)
A kilowatt-hour is a measure of energy. If you run a 1kW appliance for an hour, you will be charged for 1kWh of electricity. If you used the same appliance for two hours, that would equate to 2kWh of electricity. Kilowatt-hours are measured over time.
Load
Load means the amount of electricity used by any electrical appliance or need in a system at any given time.
Low load
As the name suggests, low load is when there’s a low amount of electricity being used or required in comparison to the amount of electricity available. For example, generally in the middle of the day there is a low demand for electricity in the energy system as most people are at work or school, however during this period the energy system is generally supplied by a high level of electricity generated by solar PV systems which can lead to a low load situation.
Low load across the energy system can cause challenges for the electricity system as a whole.
Peak demand
Refers to the highest level of demand for electricity over a given period. Peak demand in the energy system usually occurs on the hottest days, typically in summer, but demand can also peak in winter, when more people are generally using energy-hungry appliances such as air conditioning, for cooling or heating.
Power
Power is the rate at which electricity is flowing and is measured in watts or kilowatts (kW).
Renewable energy
Compared to fossil fuels and other non-renewable energy sources, renewable energy can be supplied from a source which can be replenished (or renewed). Renewable energy includes sunlight (as solar energy), wind power, tidal and wave energy and geothermal heat.
The energy generation mix in WA includes renewable and non-renewable sources.
Watt
This is the measure of electrical power either used by an appliance – or produced by a solar PV system, inverter or battery storage system. You might be familiar with watts as a measure of the power of a lightbulb. You’ll also find watts mentioned in the solar industry as a measure of the size of your solar PV system. For example, you might have a 3kW solar PV system, which means it can produce 3,000 watts of power.
Solar Glossary
There’s a lot of technical jargon used in the solar industry. Here’s a solar glossary to help you learn more about the terms you might come across when you’re looking for a solar PV system.
BOS (Balance of System)
The Balance of System (BOS) is a term used for the extra components of a solar PV system which include electrical components like wires, cables, isolators, breakers, switches, wiring and the inverter.
Clean Energy Council (CEC)
The Clean Energy Council (or CEC) is the regulatory body for the renewable energy industry in Australia. They provide accreditation for solar installers and contribute to developing industry standards.
Distributed Energy Buyback Scheme (DEBS)
DEBS is the feed-in tariff scheme available to Synergy customers with an eligible solar PV system. If you’re eligible for DEBS, you could receive a payment or credit for electricity your solar PV system generates that is exported to the energy system. This scheme is subject to terms and conditions and replaced the scheme knowns as “REBS” (Renewable Energy Buyback Scheme) in 2020.
Feed-in-tariff
This is a credit you receive on your electricity bill for excess electricity that you export or feed into the energy system generated by your solar PV system. Receiving a feed-in tariff used to be a major incentive to investing in a solar PV system as the value of a feed-in tariff was once higher to encourage people to invest in residential solar. Now, generally it is more beneficial to use more of your solar power during the day rather than exporting it the energy system. In Western Australia you need to be eligible for either DEBS (or REBS prior to 2020) to receive a feed-in tariff.
Grid-tied solar systems
Most residential solar is grid-tied. This means the grid, also known as the energy system, is used to measure the electricity produced by the solar PV system. If your household uses more electricity than your solar PV system generates at a particular time, the electricity from the energy system will make up the difference so your power stays on and everything operates as usual.
Ground mount systems
Rooftop solar PV systems aren’t always the best option. Sometimes, rather than having solar panels on your roof, a ground mount solar system may be used. In this case, your solar panels would be attached to a racking (or mounting) system which is anchored into the ground.
Inverter
Your inverter is the heart of your solar PV system. Its job is to convert direct current (DC) power into alternating current (AC) power to use in your home.
LGC (Large-scale Generation Certificates)
These are certificates that are part of Australia’s Renewable Energy Target as a measure of electricity generated from renewable energy sources. LGCs can be purchased, sold, and traded on an open market, so the value goes up and down according to supply and demand.
Meter
A meter is a device which records the movement of electricity into a residential or commercial property. The amount of electricity measured by the meter as being consumed by a property makes up part of the cost of your electricity bill.
Micro inverter
A micro inverter is a type of solar inverter. If your solar panels have micro inverters, these will be positioned on the back of each panel. This type of inverter can suit spaces with shading issues or panels which face in different directions.
Net generation
This is the process referring to the amount of solar power that your system exports to the energy system based on your usage of electricity compared with how much excess energy your solar PV system generates.
Photovoltaic (PV)
The photovoltaic process turns light energy into electricity. In terms of solar energy, the PV solar cells turn the solar energy into a flow of electrons which is then sent as a direct current to your inverter.
Off-grid
Anything ‘off-grid’ means it’s not connected to the grid, also known as the energy system, and therefore not part of the network. Properties that are off-grid need to have large solar PV system or other generation sources and enough battery storage capacity to cover the electricity needs of the household or business without being able to access any electricity from the energy system.
Racking
Racking is the mounting system which is used to attach solar panels to your roof, a building surface or on the ground.
Renewable energy buyback scheme (REBS)
REBS is no longer available to customers and was replaced by the Distributed Energy Buyback Scheme (DEBS) in 2020 to provide a feed-in-tariff for eligible solar PV systems.
Renewable Energy Target (RET)
The Renewable Energy Target is a federal government scheme designed to increase the amount of new renewable generation in Australia.
Self-consumption
Self-consumption is often the key to making the most of your solar PV system. It means using as much of the electricity your system produces as possible, so you need to buy less electricity from the energy system. You may be able to boost your self-consumption with a few simple swaps – such as setting your dishwasher and washing machine to run during the day when solar power production is generally highest, rather than running these at night which will generally require drawing electricity from the energy system.
Smart meter
In terms of solar, a "smart meter" is a device fitted into your switchboard which measures the energy coming and going from the energy system. With a smart meter for your solar PV system, the inverter can measure your solar generation, self-consumption and export. This device is often a legal requirement and can help keep the energy system balanced by limiting how much a solar PV system can export.
There is also a different type of smart meter known as an advanced meter or AMI (advanced metering infrastructure).
Solar array
The solar array is the layout of solar panels, designed to absorb the sun’s energy to generate electricity. At home, your solar array will generally be installed on your roof and the panels positioned to catch the most sunshine.
Solar cells
Solar cells are used to make solar panels and usually made from silicone. Monocrystalline solar panels have solar cells shaped like a diamond and polycrystalline solar panels have rectangular-shaped solar cells.
Solar energy
Solar energy is created from sunlight. When the sun is shining, the solar energy captured by your solar panels is converted to solar power and sent as a direct current to your inverter then converted to alternating current so you can use that solar energy to power your home.
Solar Photovoltaic (PV) System
Your solar PV system includes your solar panels, inverter and safety switches and other balance of system (BoS) elements. This is the infrastructure which turns the sun’s energy into electrical energy. With a solar PV system at home, you could offset some of your household’s electricity needs, depending on factors such as the size of the system and your household electricity usage habits.
Solar monitoring
A solar monitoring solution might help you to use real-time solar data to make the most of your solar power. You can see the amount of solar generation, how much you’re using and get automatic fault and diagnosis alerts if there are any issues. Using a solar monitoring solution could help you identify any issues quickly and help you make the most of your solar PV system’s performance and potential benefits.
Solar power
While solar energy is directly from the sun, solar power is the electricity that is generated by a solar PV system.
String inverter
This is the most common type of solar inverter, with one or more strings of solar panels attached. Working as a set in a similar way to a string of Christmas lights, this kind of inverter converts direct current from the solar panels into alternating current to be used in our homes and businesses or exported to the energy system.
STC (Small-scale Technology Certificate)
These are the certificates created when eligible rooftop solar PV systems or other small-scale renewable energy systems are installed. They are part of Australia’s Renewable Energy Target, designed to increase the amount of renewable energy generation in the country.
In most cases, solar installers allow the customer to surrender or assign the STCs created from the installation of their rooftop PV solar in exchange for a discount on the purchase price, often known as a “solar rebate” to reduce the price paid by the customer for the system.
Tier 1
This is a ranking used to help compare solar panel manufacturers on their reliability and economic stability. Tier 1 is the top ranking – so it’s worth looking for Tier 1 solar products.
Tilt angle
This is the angle of a solar panel. It’s important for your solar installer to get the angle right so your solar panels can catch the most sunlight possible.
Battery Storage Glossary
The terms used in relation to solar PV systems and battery storage are similar – but there are some extra terms you could come across if you’re exploring battery storage solutions for your home.
Battery
Batteries are electrochemical devices which store energy, for example, to be used for torches and toys – and battery storage systems for homes work in a similar way.
The role of a battery for your home if you have a solar PV system is to store excess solar power that’s generated by your solar PV system, to be used at other times.
Battery capacity
This is how much energy a battery is able to store and deliver in a single discharge. Battery capacity for home battery storage solutions is usually measured in kilowatt hours (kWh).
Battery case
Just like your mobile phone case, a battery case is a tough protective case that protects the battery cell or cells inside. Unlike your mobile phone, this battery case is usually part of the battery and doesn’t need to be bought separately.
Battery cell
A battery can be a single cell battery or made up of many individual units called cells.
Battery coupling
Battery coupling is the way which an inverter works with a battery. There’s AC coupling, which converts solar power to AC before converting it back to DC for battery storage. This can result in some of the energy being lost in the two stage conversion process prior to storage.
There’s also DC coupling, where the inverter takes solar power straight to the battery as DC power without converting it to AC. This type of battery coupling is usually more efficient than AC coupling because it involves less conversions and can be suitable for bigger solar PV systems.
Battery cycle life
Battery cycle life is not the ‘life span’ of the battery but is the number of times a battery can be fully discharged before it reaches a level of degradation that it can only store 80% of its original capacity .
Battery management system (BMS)
This is a combination of software and electronics used to control the charge and discharge of a battery. Generally the BMS is built into the battery, which can help the inverter manage the battery by not charging or discharging it too much or too quickly.
Charge/discharge rate
This is a measurement of power, expressed in kilowatts (kW) to show how quickly a battery can be charged and discharged.
The higher the charge rate, the faster your battery could charge. With a lower discharge rate, your battery may last longer but you might not be able to use it to power your bigger appliances and equipment.
Cycle
A cycle is one complete sequence of the charge and discharge of a battery.
Depth of Discharge
This indicates the level or percentage of the battery that can be discharged relative to the overall capacity. Batteries don’t usually have a 100% depth of discharge because that would shorten the life span of the battery.
While older lead acid type batteries might have a depth of discharge of about 50%, Lithium ion batteries (and some other types) can have depth of discharge of around 80 to 90%. At this point, the battery would shut off and not provide any further power to help protect the life of the battery.
Discharge
Battery discharge is process of a battery sending its energy out to be used. When a battery is fully discharged there is no usable energy left.
Discharge rate
This is a measure of how quickly a battery is discharged, measured by a C rating. As an example, torch batteries would have a low C rating while an electric vehicle has a much higher C rating.
State of Charge (SOC)
This is the percentage of charge left in the battery.
Total Energy Throughput
This is the amount of energy a battery can provide over its entire life. Total energy throughput is worth considering when you’re looking at the different prices of battery storage solutions. It’s usually expressed as megawatt hours (MWh) where one MWh is equal to 1000 KWh.
Now that you are familiar with the common terms you might come across with solar PV systems and battery storage, you might like to expand your knowledge by exploring our ultimate guide for buying solar.
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