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Storage can move daytime solar electricity into the evening, or shift cheap-rate grid energy into expensive hours. The value depends on battery losses, export income you give up, your actual tariffs and the extra installation cost.
Enter your own figures. The pre-filled inputs are illustrative examples, not current tariffs or installation quotes. This is a battery-only incremental calculation; use the main solar payback tool for the whole system.
ESTIMATED EXTRA ANNUAL CASH VALUE
—Enter your own inputs to calculate.
Method: energy charged per year is limited to usable battery capacity × estimated full cycles. Solar charging takes priority; optional grid charging uses remaining throughput. Delivered energy = charged energy × round-trip efficiency. Incremental annual value = delivered electricity × import price avoided − solar charged × export price foregone − overnight grid charge × cheap import price − additional running costs. The ten-year illustration assumes constant annual savings, tariffs and performance with no degradation, financing, replacement or discounting. This is a screening estimate, not an investment guarantee.
Without storage, unused solar generation is exported and may earn a Clean Export Guarantee payment. When you store it, you lose that payment and some electricity in the charge/discharge process. A battery only adds financial value when the higher-priced imports you avoid outweigh these costs.
Model the import-versus-export trade-off in our tariff comparison, or include an EV in the solar + EV + battery optimiser.
SEAI currently offers a separate flat €600 for eligible batteries of at least 5 kWh. Eligibility includes an MPRN, a home built and occupied before 2025, no previous battery funding at that MPRN, a registered PV contractor and an SEAI grant offer before installation begins. Installing solar at the same time is not required, but other scheme conditions apply.
Always verify the latest conditions with SEAI and check the Compound grant checker.
Confirm the usable (not nominal) battery kWh, continuous discharge kW, round-trip efficiency, cycle and capacity-retention warranties, inverter compatibility, installation position, insurance implications, servicing costs and who handles warranty repairs. Battery backup in a power cut requires a suitable isolation/changeover arrangement — it is not automatic.