Install day: 22 panels where 21 should have fit

By the evening of 4 June the roof was generating.

The quote was for 21 Aiko 475W panels, 9.98 kWp across our east/west roof. On the day, the installers measured up and decided there was room for one more on the west face. No drama and no extra charge, just 22 panels and 10.45 kWp. It pays to have installers who treat the roof as the spec rather than the paperwork.

The rest of the kit:

• Sigenergy EC 8.0SP hybrid inverter. 8 kW, with the energy management system built in.
• SigenStor BAT 6.0 and BAT 10.0 stacked together. 15.06 kWh nominal, 14.6 usable.
• G99 approval came back from the DNO with no export limit, which matters more than it sounds. The full 8 kW will be able to flow out during VPP events and Saving Sessions.

One catch: we can’t actually export yet. The final installation certification takes a month or two to go through, and until it does the export tariff sits dormant and surplus solar earns nothing. The battery soaks up most of it anyway, so the sting is smaller than it sounds, but it’s worth knowing about if you’re planning your own install. The first weeks are self-consumption only.

First impressions of the Sigenergy kit: the stack design is genuinely tidy (the battery modules and inverter click together like oversized LEGO), the app is fine, and it speaks Modbus TCP over the LAN, which is the bit we really cared about. Local control is what makes everything in the stack possible.

The sales projection says this system should generate around 7,500 kWh a year and return somewhere near £1,900 to £2,000 of value in year one against an £11,999 price. Whether that survives contact with reality is what the stats page is for.

Update, 5 June: it turns out the inverter on the wall is not the one we ordered. That story has its own post.