Our best March too: 666.52 kWh in 2025... 612 kWh in 2022 and 605 kWh in 2020.

390 kWh last year. So a good month for our 6.16kW array.

May 2020 remains our all-time record with 987 kWh. 

660kWh from 9kWp in Hertford.  Array split 10 panels east and 14 west.

6.1kw array, South facing.

West Midlands. 

701kWh generated.  519 kWh exported. 

We've had a good time of it so far this year.

That's from a 6.5kWp array of 18 panels, mainly South facing but with two that are East facing to catch the early sun.

The other aspect of maximising solar production is tying in with best export rates and time of use tariffs.

I moved to Octopus Intelligent Go so focus on filling batteries every night at 7p as well as maximising exports during day - including forced exports from batteries. Aiming to get batteries down to around 20% by 11pm. Slow inverter charge/discharge rates reduces ability to maximise.

Export Mar2025 463kwh

Mar2024 60kwh

Mar2023 44kwh

Last year I exported 2585kwh. Hopefully 5000kwh+ this year.

@majordennisbloodnok It is the early sun that catches the photons, err… perhaps that isn’t quite right though. 🤨

Solar Yield in Toodle Villas:

March 2023 390.7 kWh

March 2024 436.6 kWh

March 2025 654.6 kWh

Perhaps the upward swing will continue throughout the summer?

We have 8.1 kWp over 21 panels variously orientated with 11 across 3 roofs and 10 garden mounted; various shading probs at different times. S.E. England

Regards, Toodles.

Posted by: @tim441

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The other aspect of maximising solar production is tying in with best export rates and time of use tariffs.

I moved to Octopus Intelligent Go so focus on filling batteries every night at 7p as well as maximising exports during day - including forced exports from batteries. Aiming to get batteries down to around 20% by 11pm. Slow inverter charge/discharge rates reduces ability to maximise.

Export Mar2025 463kwh

Mar2024 60kwh

Mar2023 44kwh

Last year I exported 2585kwh. Hopefully 5000kwh+ this year.

 

Yours is a slightly unusual case, @tim441, since the GivEnergy batteries are warranted for 12 years with unlimited cycles. For most of the rest of us, though, the batteries are rated for a set number of charging cycles and that affects the sums considerably. Admittedly battery prices have come down a lot recently but my 6.5kWh battery was, last I checked, about £1,400 and it is rated for 6,000 cycles which means every kWh I put in and consume later has a paper cost of about 4p which has to be added to the unit import cost to weigh up whether exporting is financially worthwhile. The Fogstar unit I've been starting to think about is rated to 4,000 cycles so that cost per kWh goes up to 6p, but the fact I can get an IP65-rated enclosure with four batteries to a total of 20kWh (or eight batteries/40kWh) means the possibility of being able to go through a whole day on battery power and therefore greater flexibility of purchase time/price.

We're on Octopus Agile so it is generally far more financially effective to simply fill the battery from solar and top up from grid during a cheap period to tide us over the 4pm-7pm stretch. If the car is at home during the day then excess solar PV is best diverted into the car's battery rather than exporting and trying to find a cheap import time for car charging.

It's a complicated old business and one of several significant reasons I don't try to juggle it all manually. Some form of rule-based home automation system is far more practical for me and it so happens I use Home Assistant.

I did a fairly detailed comparison and found that under IOG February would have cost me £369.28 whereas under Octopus Agile it actually cost me £362.72. Not much in it.

@majordennisbloodnok yes, really difficult making like for like comparisons with so many variables. Definitely no "one size fits all!"

One thing that makes IOG even harder to compare is due to the extra cheap rate slots that get offered in daytime or extending the cheap overnight period. From my limited experience to date in Feb & Mar it seems very practical to get the average import rate down below 8p/kwh. Clearly only possible with reasonable battery size.

Outcome really surprised me.

Posted by: @majordennisbloodnok

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the GivEnergy batteries are warranted for 12 years with unlimited cycles

[...]

The Fogstar unit I've been starting to think about is rated to 4,000 cycles...

I doubt that the LiFePO4 cells used in the GivEnergy enclosures are going to behave any different to those you would install into a FogStar or Seplos box.

The available capacity will decrease over time, but the battery is still functional and thus "operating within the guarantee".

There's problem I can foresee occuring for GivEnergy users who initially buy a couple of battery modules, wait a year and then add a few more.
The latest GivEnergy design is to have the batteries connected in series.
So the first cells in the stack will have lower capacity than the others.
When recharging, they will reach their top-voltage (3.6v) first.

How GivEnergy copes with that depends on the functionality available from their integral BMS (battery management system).

If the BMS has active balancing then it can shift energy between cells.

When charging, it needs to move energy from the older cells to the newer ones...
... and the reverse process when discharging.

But I have no idea if that's the approach they're using.
Active balancing of cells isn't common.

Most BMS units simply 'burn off' excess energy from cells which have reached their top-voltage
by passing it through a resistor.

Posted by: @majordennisbloodnok

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Posted by: @majordennisbloodnok

↑

the GivEnergy batteries are warranted for 12 years with unlimited cycles

[...]

The Fogstar unit I've been starting to think about is rated to 4,000 cycles...

 

 

I doubt that the LiFePO4 cells used in the GivEnergy enclosures are going to behave any different to those you would install into a FogStar or Seplos box.

The available capacity will decrease over time, but the battery is still functional and thus "operating within the guarantee".

...

I don't expect the batteries will behave any differently either. To be frank, I can't even see the reason for a Fogstar battery and a Growatt battery having significantly different warranted cycles. However, the warranty the GivEnergy batteries carry encourages very active charge/discharge use and if the thing fails in its warranted 12 years then GivEnergy have an obligation to repair or replace. I doubt people with a battery rated to 4,000 cycles are going to work their kit quite so hard knowing that once they get to the cycle limit they're on their own. That difference of user perception could matter a lot in terms of maximising ToU tariffs.

@majordennisbloodnok But then, who can tell if the manufacturer will even be around in 10 years; their MD or CEO might just throw a wobbly err… speaking of which, my battery is made by a company called Tesla ….😳 Toodles.

Posted by: @toodles

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@majordennisbloodnok But then, who can tell if the manufacturer will even be around in 10 years

...

Totally agree, @toodles. The issue is more one of how much or little people are inclined to push their kit to work for them. Bear in mind that my car's battery has been warranted to 8 years/100,000 miles with the expectation it will still be at 70% of capacity, so a 6,000 cycle warranty on a solar PV battery does not mean it's kaput after that. Nonetheless, I suspect a generous warranty will encourage people to make most use of the battery whereas a more modest one will encourage people to be more cautious.

Silly thing is, of course, that 4,000 cycles is a one full cycle per day for just under 11 years so giving it a bit of welly isn't going to make a practical difference. It's just that there's a finite number there rather than a more relaxed "do what you want for the next x amount of time". All about perception, eh?