Smart Export

Hi, just want to check with other users re, solar panel performance so for this year my best months for export/generation have been April and May, which is a bit strange considering we've just had the hottest summer on record, maybe not the sunniest. Can anyone confirm, seems to be the best way to check I've not had a panel go down.
Another question, I have 9 panels and a 5.4Kw/hr battery, which so far very pleased with, I'm on Octopus Smart Flux, again very pleased with export tariff, but is it the best deal for the winter ? and is it possible to swap deals but retain the export deal.
Thanks
Graham B

PV production has nothing to do with heat, but solar intensity. So depending where pv panels mounted, roof?, the angle and orientation is more critical. April/May in South UK often produces the most Kw as that is when the suns rays are striking the panels at the optimum angle on a 26-30° roof.

grahambowen check pvoutput.org to see similar setups in your vicinity. For me, June was very slightly higher than April/May, but July/August lower. Heat tends to reduce generation, so cooler months can generate more.

Intelligent Flux ? Sorry, import and export come as a pair.

I have found that heat can affect the PV panels. Cooler days are better than hotter days with the "same" sunshine. YMMV

I have two arrays of 8 panels - East and West. For August 2025 - 729kWh generated, August 2024 - 693 kWh. So slightly more this year.
If it helps for comparison with your generation data (this year):

• April 745kWh,
• May 919kWh,
• June 894kWh.

alan_johnston Nobody's mileage will vary - much 😉

Basically photovoltaic cells work more efficiently at lower temperatures.

PV panel rated power outputs are usually based on the following criteria - Solar irradiation 1 kW/m2 with light spectrum AM 1.5 and a cell temperature of 25°C.

Cell temps over 25C will result in lower power output - somewhere about 0.4% per degree C

Likewise cell temps below 25C will result in higher power output - 0.4% per degree again. That's why the best months for generation are often April/May/August/Sept. Its also why you may see higher than rated power output on cold sunny days.

Remember that the cell temperature is likely to be higher than ambient air temperature when in sunlight. I've no idea how much that is but 5C seems likely (and is probably on the low side, certainly with in-roof panels).

grahambowen If you are on Octopus Intelligent Flux or Octopus Flux then you’d probably be better changing to a non-Flux tariff in October when your solar generation starts dropping off, These are paired tariffs so you can’t get the export without paying the import rate as well, and in the winter your generation will be a fraction (10% or less) of what it is in summer