A
AC coupling
Connecting a battery to an existing solar system via an AC inverter on the battery side, rather than sharing a DC inverter with the panels. Lets you add a battery to almost any solar setup. Tesla Powerwall 3 supports AC coupling natively.
Approved product list (SAA)
The official list maintained by SAA of battery models eligible for the federal Cheaper Home Batteries Program. Models on the list are pre-certified for safety, performance and warranty terms.
B
Battery Management System (BMS)
The on-board electronics that monitor and control each cell in a battery - temperature, voltage, charge level. A good BMS extends battery life by 30%+ vs an absent one.
Backup mode
The feature that lets a battery continue powering your home during a grid outage. Tesla Powerwall 3 supports whole-home backup automatically; Sungrow and BYD typically support selected-circuit backup.
C
CEC accreditation
Clean Energy Council accreditation - held by most reputable WA solar and battery installers. Required for some rebates and often a prerequisite for SAA accreditation.
Cheaper Home Batteries Program
Australian federal government rebate launched 1 July 2025. Pays roughly $372 per kWh of usable battery capacity at point of sale via STC certificates. Rate steps down each year through 2030. Stacks with the WA state rebate.
Cycle life
The number of full charge-discharge cycles a battery completes before significant capacity loss. Modern LFP batteries last 4,000–6,000+ cycles, equating to 10–15 years of daily use.
D
DEBS (Distributed Energy Buyback Scheme)
Synergy's tariff for solar exported to the grid. Pays approximately 10c/kWh during peak (3pm–9pm weekdays) and 2.5c/kWh otherwise. Designed to incentivise households to shift solar export into the evening peak when the grid needs it most. Batteries can store midday solar to discharge during this peak window - the "DEBS arbitrage".
Depth of Discharge (DoD)
The percentage of a battery's nameplate capacity that's safely usable. Modern LFP batteries (Tesla, Sungrow, BYD) support 90–100% DoD. Older lead-acid systems capped at 50%.
E
Export limit
The maximum kW a household can push back into the grid. Synergy's SWIS standard limit is 5 kW per single-phase home, 30 kW per three-phase. Horizon Power microgrids have varying export limits - some near zero, some up to 5 kW.
F
Federal rebate
See Cheaper Home Batteries Program.
Feed-in tariff (FiT)
Historical Synergy export rate, mostly replaced by DEBS from 2020 onwards. Legacy customers on the original 40c/kWh FiT remain on it until 2030 - these households often skip battery installs because export economics still favour them.
H
Horizon Power
The WA state-owned utility serving regional Western Australia - Pilbara, Kimberley, Mid West, Goldfields-Esperance, Gascoyne. Runs around 30 standalone microgrids. Horizon customers qualify for a $7,500 WA battery rebate cap (vs $5,000 for Synergy customers).
Hybrid inverter
An inverter that manages both solar PV input and battery charge/discharge from one device. Common pairings: Sungrow SH-RS series, Fronius Symo Hybrid, GoodWe ET Plus. Required for retrofit battery installs unless using an AC-coupled product like Tesla Powerwall 3.
I
Inverter
The device that converts DC power (from solar panels or batteries) into AC power that your home appliances use. Solar inverters convert solar only. Battery inverters convert from batteries only. Hybrid inverters do both.
K
kW (kilowatt)
A unit of power - the rate at which energy flows. A 6.6 kW solar system can generate up to 6.6 kW at peak sun. Batteries are rated for kW (continuous output power, e.g. 5 kW) and kWh (energy storage, e.g. 13.5 kWh) separately.
kWh (kilowatt-hour)
A unit of energy. A 1 kW appliance running for 1 hour uses 1 kWh. Most WA homes use 20–35 kWh/day. Battery sizes are quoted in kWh: 10 kWh, 13.5 kWh, 20 kWh, etc.
L
LFP (Lithium Iron Phosphate)
The current dominant battery chemistry for home storage - safer, longer-lasting and more thermally stable than the NMC chemistry used in earlier batteries and most EVs. Tesla Powerwall 3, Sungrow SBR and BYD Battery-Box Premium all use LFP cells.
M
MPPT (Maximum Power Point Tracking)
An inverter feature that keeps solar panels operating at their peak power output as light conditions change. Hybrid inverters typically have 2–3 MPPT inputs, letting you connect multiple solar arrays with different orientations.
Microgrid
A localised electricity network. Most of Horizon Power's coverage is via microgrids - standalone power systems serving one town or region, often diesel-backed. Microgrid rules (export limits, tariffs) vary site by site.
N
NMI (National Metering Identifier)
The unique 10-digit identifier for your electricity meter, printed on every Synergy / Horizon bill. Battery rebate applications use the NMI to confirm one-rebate-per-property compliance.
Net metering
An older billing model where solar exports were netted against grid imports on a 1:1 basis. Replaced in WA by DEBS with different peak / off-peak buyback rates.
O
Off-grid
A home not connected to either Synergy or Horizon. Off-grid homes are not eligible for the WA Residential Battery Rebate (the scheme requires grid connection), but they are eligible for the federal Cheaper Home Batteries Program.
Off-peak
Time-of-use tariff periods with lower kWh rates - typically 9pm–6am on Synergy Smart Home Plan. Average off-peak rate is ~15c/kWh vs 50c/kWh during peak. Batteries can charge off-peak and discharge during peak for arbitrage gains.
P
Peak rate
Time-of-use tariff periods with the highest kWh charges - typically 3pm–9pm weekdays on Synergy Smart Home Plan. Around 50c/kWh. Battery's primary value is offsetting consumption during this window.
Powerwall 3
Tesla's 13.5 kWh home battery, the most common premium battery in WA installs in 2026. Built-in hybrid inverter, whole-home backup, best continuous power output (11.5 kW). Full review.
R
Retrofit
Adding a battery to an existing solar system rather than installing both together. Compatible if your existing inverter can be replaced with a hybrid model, or if you use AC-coupled hardware like Powerwall 3.
S
SAA (Solar Accreditation Australia)
The body that accredits installers and maintains the official approved product list for battery rebates. Federal Cheaper Home Batteries Program eligibility requires an SAA-accredited installer using an SAA-approved battery model.
Smart Home Plan (Synergy)
Synergy's time-of-use tariff plan. Higher peak rates, lower off-peak rates than the flat Home Plan A1. Suits most battery + solar households because batteries can arbitrage between the two rate periods.
State of Charge (SOC)
The percentage of a battery's capacity currently filled - like a fuel gauge. Battery apps show SOC in real time. Most batteries are programmed to maintain 5–15% SOC minimum as a reserve.
STC (Small-scale Technology Certificate)
The certificates the federal Cheaper Home Batteries Program uses to deliver the rebate. Your installer calculates the STCs your battery qualifies for, and the certificates are sold to liable energy companies. The discount appears on your invoice.
Sungrow SBR
Sungrow's modular home battery line. Sizes from 9.6 kWh to 25.6 kWh in 3.2 kWh modules. Common in WA installs. Full review.
SWIS (South West Interconnected System)
The main WA electricity grid covering Perth metro and the south west. Operated by Western Power. Synergy is the retailer. Most metro WA postcodes are SWIS.
Synergy
The state-owned electricity retailer serving WA's SWIS network - Perth metro, south west, and parts of the wheat belt. Synergy customers qualify for a $5,000 WA state battery rebate cap.
T
Time-of-use (TOU)
Tariff plans with different kWh rates at different times of day. Synergy Smart Home Plan is a TOU tariff. Compared to flat-rate Home Plan A1, TOU plans suit battery households who can shift consumption.
Tier 1 (battery)
Industry term for premium battery brands with bankable warranties, established manufacturing and long-term support commitments. Tesla, Sungrow, BYD, LG (now exited), and Sigenergy are commonly cited as Tier 1.
W
WA Residential Battery Rebate Scheme
The Western Australian state rebate launched 1 July 2025. Pays up to $5,000 (Synergy) or $7,500 (Horizon) per household for an eligible battery install. Capped at 100,000 households total, first-come first-served. Funded at $337 million. Full guide.
Whole-home backup
A backup configuration where every circuit in the home runs from the battery during a grid outage - not just selected circuits. Tesla Powerwall 3 supports whole-home backup natively. Sungrow and BYD require additional hardware.