UK Fox ESS solar generation stats: July, August & September 2026 in review
If you are searching for UK Fox ESS generation stats through the peak summer months, this post is a straight readout of July, August & September 2026 on my roof. Every number below is what my inverter reported, pulled into Check My Solar and added up the same way you would see it in the app’s History view or on a public share card.
Day to day I charge the batteries to 100% on off-peak overnight, then switch to feed-in mode so daytime solar goes to export. The import figures in the tables include that overnight charging.
My system setup
| Component | Detail |
|---|---|
| Inverter | Fox ESS H1 G2 Hybrid |
| Panels | 13× Aiko Neostar 2S 460 W (~5.98 kWp) |
| Storage (Jul–Aug) | Fox ESS EP5 5.18 kWh × 2 (10.36 kWh) |
| Storage (from Sep) | Fox ESS EP6 5.21 kWh × 2 added early September (+10.42 kWh; ~20.8 kWh total) |
| Location | United Kingdom |
| Installed | 23 May 2025 |
At the start of September 2026 I added a second stack: two EP6 5.21 kWh modules alongside the existing two EP5 units. July and August in this post are therefore still on the 10.36 kWh pair only; September mixes a few days at that size with most of the month at the larger total.
Solar generation
The three months added up to 2,542.7 kWh of solar, averaging about 27.6 kWh/day across the quarter. July was the stand-out month at 1,101.9 kWh (~35.5 kWh/day), which is the strongest full calendar month I have logged so far on this inverter.
Monthly totals (2026)
| Month | Generation (kWh) | Avg per day (kWh) | Peak day | Peak (kWh) |
|---|---|---|---|---|
| July | 1,101.9 | 35.5 | 7 July | 40.7 |
| August | 886.3 | 28.6 | 1 August | 38.5 |
| September | 554.5 | 18.5 | 6 September | 29.8 |
| Q3 total | 2,542.7 | 27.6 | n/a | n/a |
July’s peak at 40.7 kWh on 7 July was only a little below my 2026 best so far (42.6 kWh on 19 June). September cooled off as expected for early autumn, but still cleared 550 kWh for the month.
Grid export
Export stayed high all summer with feed-in mode on during the day. More than two thirds of generation left the roof as export each month. My export tariff pays 15p per kWh; the export value column below is exported kWh × £0.15 (before any standing charges or import costs).
| Month | Generation (kWh) | Exported (kWh) | Export % of generation | Export value (15p/kWh) | Grid import (kWh) | Net grid (export − import) |
|---|---|---|---|---|---|---|
| July | 1,101.9 | 758.9 | 68.9% | £113.84 | 306.9 | +452.0 |
| August | 886.3 | 652.0 | 73.6% | £97.80 | 290.7 | +361.3 |
| September | 554.5 | 397.0 | 71.6% | £59.55 | 357.5 | +39.5 |
| Q3 | 2,542.7 | 1,807.9 | 71.1% | £271.19 | 955.1 | +852.8 |
On top of day-to-day export payments, I earned £152.26 from Axle virtual power plant events over the same three months (extra export when the grid needs it). That is separate from the 15p/kWh SEG line in the table above.
| Export income (Jul–Aug–Sep 2026) | Amount |
|---|---|
| SEG at 15p/kWh | £271.19 |
| Axle VPP events | £152.26 |
| Combined | £423.45 |
If you are on Fox ESS in the UK and want to try Axle, sign up with referral code R-QNHHEHMY for £25 credit when you join: vpp.axle.energy/landing?ref=R-QNHHEHMY. You can then link Axle in Check My Solar (Settings → VPP) to see upcoming events and earnings on Today, as in our September product update.
September grid import was higher (357.5 kWh vs 260.9 kWh in September 2025), mostly from the same overnight off-peak top-ups as earlier in the quarter, with a bit more to fill after the EP6 batteries went in.
Battery performance
| Month | Charged (kWh) | Discharged (kWh) | Round-trip efficiency | Approx. cycles (leaderboard) |
|---|---|---|---|---|
| July | 188.1 | 189.4 | ~100.7% | 18.3 |
| August | 182.5 | 181.9 | ~99.7% | 17.6 |
| September | 250.0 | 228.3 | ~91.3% | 11.0 |
| Q3 | 620.6 | 599.6 | ~96.6% | n/a |
Round-trip percentages above 100% on a single month are a quirk of Fox rounding on small daily buckets, not a real physics win. September shows the highest charge total (250.0 kWh) even though generation was lowest: bigger batteries plus the same nightly off-peak top-up routine. July and August cycling stayed in a similar band on the 2× EP5 setup before the EP6 pair arrived.
House load over the same period was 1,443.3 kWh (Fox loads total), so a large share of consumption still came straight from solar and battery rather than import.
Year on year: July, August & September 2025 vs 2026
Same three months last year, from the same archived month reports:
| Metric | Jul, Aug & Sep 2025 | Jul, Aug & Sep 2026 | Change |
|---|---|---|---|
| Generation (kWh) | 2,176.3 | 2,542.7 | +16.8% |
| Export (kWh) | 1,347.3 | 1,807.9 | +34.2% |
| Export % of generation | 61.9% | 71.1% | +9.2 pts |
| Grid import (kWh) | 810.9 | 955.1 | +17.8% |
| Battery charged (kWh) | 453.6 | 620.6 | +36.8% |
| Month | Generation 2025 (kWh) | Generation 2026 (kWh) | YoY |
|---|---|---|---|
| July | 864.8 | 1,101.9 | +27.4% |
| August | 736.7 | 886.3 | +20.3% |
| September | 574.8 | 554.5 | −3.5% |
2026 benefited from a very strong July and a higher export share while I kept feed-in mode on through the day. The EP6 pair landed too late to reshape July or August, but they explain why September import and battery throughput ticked up even as generation dipped slightly year on year, with more capacity to fill on off-peak each night.
Leaderboard and share link
I opt in to the Check My Solar leaderboard so other Fox ESS owners can compare aggregated kWh, export, and efficiency (kWh per kWp) without exposing live data. Through 30 September 2026, my year-to-date generation on that profile was 6,139.7 kWh with 4,163.4 kWh exported.
You can browse the same public card here:
share.checkmy.solar/v0vc5af8bbbj?period=year&date=2026
For month-specific views, switch the period in the URL (for example period=month&date=2026-07). Read how leaderboard privacy works before you opt in.
Track your own Fox ESS system
Want tables like this for your install?
- Sign in to Check My Solar and link your Fox ESS inverter
- Open History for daily, monthly, and yearly totals (with a calendar heatmap for spotting best and worst days)
- Optional: join the leaderboard and share your own stats link
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