Solar PV

Grid Import — Before & After

Our new hot tub was installed in July 2025 — you can see the uplift in electric demand in the graph below, from June onwards. To maintain the tub at a “proper” 37°C there is a heating cycle every couple of hours, plus extra for when the jets and pumps are running.

Usage averaged 22–24kWh a day, increasing to 38kWh when the tub was getting heavy use (+4 hours a day).

Whilst the solar install won’t save me any money when comparing 2026 usage against 2025, it does offset the increased costs of the hot tub and the 12+ hours a day of air-conditioning usage in the blistering summer months.

In the last 12 months we imported 4,229.8kWh from the grid (£1,100 est.) against a total demand of 7,922.9kWh. We exported 2,009.5kWh — but under SEG we only got roughly 14p per kWh (£281 est.). We couldn’t use this as we didn’t have enough storage. But now, with the increased battery capacity, we will be able to use this generated power to offset the imported energy, saving us another £500+ a year.

The next step, when the time comes, is to switch tariff to allow cheap overnight charging of the batteries to full capacity. I also want to explore the option of getting an air-source heat pump solely for the hot tub — that would reduce the water heating costs even further.