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After Japan's FIT Ends: Will a Battery Pay for Itself?
For homes that already have solar, calculate how a retrofit battery changes self-consumption, bill savings and export income after the FIT ends, and how long it takes to pay back.
Figures on this site are estimates from JMA climate normals and published averages for rules and costs. They are not quotes and do not guarantee output or savings. Roof shape, shading, equipment, how you use electricity and your tariff change the results a lot. Before buying, get site surveys and quotes from several installers and check your utility tariff and local subsidies.
FAQ
What happens when the FIT period ends?
The 10-year purchase period for home solar ends ("sotsu-FIT"), which began in November 2019. You can keep selling to your current utility, switch to another buyer, or use more yourself with a battery. In most cases your current utility keeps buying if you do nothing.
Should I add a battery after the FIT ends?
Export prices (around ¥7–10/kWh) are far below what you pay (around ¥30/kWh), so storing surplus for the evening raises the value of each kWh. Whether the battery pays for itself depends on how much you can store, its price and subsidies. Calculate it on this page.
Can I use stored power during a blackout?
Most home batteries can, but whether the whole house or only selected outlets are backed up, and whether 200 V appliances work, depends on the model.
More (Japanese): Agency for Natural Resources and Energy: after the FIT
Sources: radiation and temperature from JMA climate normals (1991–2020); feed-in tariff and renewable surcharge from METI (March 19, 2026); PV system and O&M costs from the Procurement Price Calculation Committee (110th meeting); battery cost from METI (March 2025); default electricity price from the appliance fair trade council. Calculated by this site (checked 2026-11-01). Links are in Japanese.