Perth solar glossary: plain-English definitions for the terms you'll encounter

Solar quotes and energy conversations in Perth come loaded with abbreviations and technical terms. Here are the most common ones explained in plain English.

Tariff and export terms

A1 tariff Synergy's standard residential electricity tariff. In 2026, the A1 rate is 33.26c/kWh (plus a supply charge of 119.24c/day). You pay the same rate for all electricity you consume, regardless of time of day.

Midday Saver (Smart Home tariff) Synergy's time-of-use tariff for solar households (requires a smart meter). Three rates apply:

• Super off-peak: 8.85c/kWh (9am–3pm)
• Off-peak: 24.34c/kWh (before 9am and 9pm–midnight)
• Peak: 55.33c/kWh (3pm–9pm)

DEBS (Distributed Energy Buyback Scheme) The current WA solar feed-in arrangement for households who export excess solar to the grid. Two rates: 10c/kWh during peak (3pm–9pm), 2c/kWh during off-peak (all other hours). Launched 1 November 2020; applies to all new solar installations.

REBS (Renewable Energy Buyback Scheme) The previous WA feed-in arrangement (2010–2020). Flat rate of 7.135c/kWh for all exported electricity. REBS is closed to new entrants; existing REBS participants remain on this scheme unless they upgrade their system (which triggers a permanent switch to DEBS).

SWIS (South West Interconnected System) The WA electricity network that connects Perth, Mandurah, Bunbury, Geraldton, Kalgoorlie, and most of regional WA. Synergy is the electricity retailer on the SWIS. All household solar in Perth connects to the SWIS.

Solar system components

PV (Photovoltaic) Photovoltaic refers to the technology that converts sunlight directly into electricity using solar cells. "Solar PV" is distinct from "solar thermal" (which uses sunlight for heat, not electricity).

Inverter The device that converts the direct current (DC) electricity produced by solar panels into alternating current (AC) that your household appliances and the electricity grid use. The inverter is the brain of the solar system — it manages power output and grid connection.

String inverter A conventional inverter where all panels are wired in a series circuit ("string") to one inverter. Cost-effective but sensitive to shade on any single panel in the string.

Microinverter An inverter mounted on each individual panel. Panels operate independently. Shade on one panel doesn't affect others. Higher cost but better performance in shaded or complex roof scenarios.

MPPT (Maximum Power Point Tracking) The technology that constantly adjusts the electrical operating point of panels or a string to extract maximum power under varying conditions (changing sun angle, partial shade, temperature). Most modern inverters have 1–4 MPPT inputs, allowing different strings to be optimised independently.

Optimiser (DC optimiser) A device attached to each panel that performs MPPT at panel level, before the string current reaches the inverter. SolarEdge and Tigo are common brands. Provides per-panel performance data and reduces the impact of shade on other panels.

Rebate and policy terms

STC (Small-Scale Technology Certificate) The federal government rebate mechanism for solar and heat pump systems. STCs are created when a system is installed, based on the system size and location (Perth is in Zone 3). The installer typically assigns the STCs to a certificate agent in exchange for a discount on your invoice. The number of STCs you receive decreases annually until 2030.

STC Zone / STC multiplier STCs are calculated using a multiplier based on geographic zone (solar irradiance). Perth is in Zone 3, with a multiplier of 1.382. Higher multipliers (more solar irradiance) generate more STCs per kW.

WA Battery Scheme / WA Battery Rebate The WA state government rebate for home battery installations. $130/kWh of installed battery capacity, maximum $1,300 (i.e. for up to 10kWh). Requires the battery to be on Synergy's Sustainable Smart Living (SSL) product list and installed in the SWIS network area.

SSL (Synergy Sustainable Smart Living product list) The approved product list for WA Battery Scheme rebate eligibility. Only batteries on this list qualify for the rebate. Check synergy.net.au for the current SSL before accepting a quote that includes a battery rebate.

Battery terms

kWh (Kilowatt-hour) A unit of energy. 1 kWh = running a 1,000W appliance for 1 hour. When describing batteries, kWh refers to capacity (how much energy the battery can store). A 10kWh battery stores enough energy to run a typical Perth household for approximately 6–8 hours.

Usable capacity vs nominal capacity Battery specifications typically quote nominal capacity (total capacity) and usable capacity (what you can actually use, accounting for the buffer the battery management system reserves). For example, a battery with 10kWh nominal capacity might have 9.5kWh usable.

DoD (Depth of Discharge) The percentage of a battery's capacity that is discharged during normal operation. Most home batteries are rated at 80–90% DoD. A 10kWh battery at 80% DoD provides 8kWh of usable energy per cycle.

SoH (State of Health) A measure of a battery's current capacity relative to its original capacity, expressed as a percentage. A battery with SoH of 85% can store 85% of what it could when new. Monitored via the battery's monitoring app. Declining SoH indicates degradation.

LFP (Lithium Iron Phosphate) The dominant chemistry for Perth residential batteries (BYD, Sungrow, Sigenergy use LFP). Known for thermal stability (onset of thermal runaway at 270–300°C vs 150–200°C for NMC), long cycle life (3,000–6,000+ cycles), and no cobalt.

NMC (Nickel Manganese Cobalt) An alternative battery chemistry (used in earlier Tesla Powerwall 2 and many EV batteries). Higher energy density than LFP but lower thermal stability and cycle life. Still found in some residential storage products.

Installation and connection terms

CEC (Clean Energy Council) The industry body that accredits solar installers and approves solar products in Australia. CEC accreditation is required for an installer to install systems that are eligible for STC rebates. Check CEC accreditation at cleanenergycouncil.org.au.

NCN (Network Connection Notification) The notification your solar installer submits to Western Power after installation, informing the network operator that a solar system has been connected to the grid. Required before DEBS credits can be activated.

Western Power The electricity distribution network operator for the SWIS. Western Power owns and operates the poles and wires. Synergy (the retailer) deals with billing; Western Power deals with connections, metering, and the physical network.

Export limit The maximum power (in kW) that your solar system is permitted to export to the grid at any time, set by Western Power. Standard residential export limits in Perth are typically 5kW. Exceeding the export limit is managed by the inverter (which throttles output).

Performance terms

Peak sun hours (PSH) The number of equivalent full-intensity sun hours a location receives per day. Perth averages 5.0 peak sun hours per day annually. A 6.6kW system in Perth theoretically generates 6.6 × 5.0 = 33kWh/day, less system losses (approximately 15–20%).

PR (Performance Ratio) A measure of how efficiently a solar system converts available solar energy into usable electricity. Industry standard for Perth residential systems: 75–85%. Losses come from inverter efficiency, cable losses, temperature effects, and soiling.

Generation estimate The projected annual energy output of a solar system, used to calculate savings in quotes. Estimates should use Perth-specific irradiance data and realistic performance ratios. Ask your installer for the data source behind their estimate.

Terms may vary slightly in usage between installers and context. This glossary covers Western Australian usage.