The October PV "cliff"

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Oldgreybeard
Posts: 1873
Joined: Thu Sep 09, 2021 3:42 pm
Location: North East Dorset

The October PV "cliff"

#1

Post by Oldgreybeard »

I can certainly tell that October is here. PV generation has done it's usual October "falling off a cliff" trick. Rather than the 40 or more kWh per day we were getting a few weeks ago today we hit the giddy heights of 6.57kWh/ Just about enough to stop us pulling power from the grid all day, but the batteries are down to 52% now, so will end up charging during the off-peak period tonight. First time the battery SoC has dropped low enough to resort to charging from grid power since early April.

Still, no need for heating yet, the thermostat in the hall is sat at 22.8°C, so unless we get several cold days in a row I don't think we'll need the heating for a while yet. Might well be November before the heating is needed, with a bit of luck, and we're usually finished with heating by mid-March, so not too long to have to draw energy from the grid to stay comfortable.

Just hope tomorrow turns out to be a bit better than today, as the car could do with a top up. Not helped that we've had a couple of guys here every day for the past fortnight building a stone wall. That's meant more energy being used for making mugs of coffee plus the power needed to run their cement mixer for long periods every day. The older guy can't get over the fact that their mixer is running off batteries. . .
25 off 250W Perlight solar panels, installed 2014, with a 6kW PowerOne inverter, about 6,000kWh/year generated
6 off Pylontech US3000C batteries, with a Sofar ME3000SP inverter
marshman
Posts: 614
Joined: Thu Jun 17, 2021 7:58 pm

Re: The October PV "cliff"

#2

Post by marshman »

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Last edited by marshman on Sun Jun 11, 2023 2:54 pm, edited 1 time in total.
openspaceman
Posts: 662
Joined: Mon Mar 21, 2022 7:37 pm

Re: The October PV "cliff"

#3

Post by openspaceman »

Yesterday broke a 213 day run without buying electricity from the grid barring the 1/3kWh per day this system seems to draw daily. Battery dropped to 10% at 19:00 so running on grid now. Also had to heat water with gas which cost £1.39.
Morso S11
FIT
16 Sharp PV panels facing WSW 4kW
Solarmax 4200S inverter
Non FIT
3 Canadian solar DC coupled 1.75kW facing SSE
Storage
Growatt SPA3000TL BL inverter ac coupled
Growatt GBLI6532 6.5kWh lithium phosphate battery
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nowty
Posts: 5733
Joined: Mon May 31, 2021 2:36 pm
Location: South Coast

Re: The October PV "cliff"

#4

Post by nowty »

Come October the grid on the cheap slot comes on like a switch here at Nowty Towers. But because of two long distance EV journeys, it was switched on a week early the last week in Sept.

I'm not actually charging the home battery with the grid yet, but yes on the EVs, one small storage heater and the hot water. But this year the secret weapon is Ripple WT1 and the bonus of the £400 energy credit.

That should see us through till WT2 becomes operational.
16.9kW PV > 109MWh generated
Ripple 6.6kW Wind + 4.5kW PV > 25MWh generated
5 Other RE Coop's
105kWh EV storage
60kWh Home battery storage
40kWh Thermal storage
GSHP + A2A HP's
Rain water use > 510 m3
Oldgreybeard
Posts: 1873
Joined: Thu Sep 09, 2021 3:42 pm
Location: North East Dorset

Re: The October PV "cliff"

#5

Post by Oldgreybeard »

Today was a good illustration of PV variability at this time of the year. Right now the house battery is at 100%, the car is charged to 100% and the hot water is fully charged, so I've switched the battery system back to "auto" (effectively takes us pretty much off-grid, apart from big peaks in demand). I really didn't expect to be able to switch back from time-of-use mode to auto mode this late in the year, but we generated over 26kWh today, most of which went into the car (that took around 12kWh) to replenish a day trip out to Mottisfont from last week, around 3kWh went to heat the hot water for tomorrow and most of the rest topped the battery up, ran the washing machine and the dishwasher, as well as cooking lunch.

Not often we get a completely "free" day in October, and tomorrow looks to be much the same. I think we need to have a drive out tomorrow morning just so we can top the car back up again for free. We do have a drive planned for tomorrow (wedding anniversary, so we are off out for lunch at James May's pub), but that's not far enough to need much of a charge when we get home. My guess is that we will be exporting to the grid for a fair bit of tomorrow, that's not something that's happened for a couple of weeks or so.

We will burn off some of the battery capacity tonight, though, as it's so warm here that I've had to turn the aircon back on. That's been on for the past hour or so, but the hall thermostat is still reading 23.6°C, so it's a bit too warm, really. Probably means that it's going to be a while yet before the heating comes on, though. I can't see us needing heating for at least another week or two, maybe longer.
25 off 250W Perlight solar panels, installed 2014, with a 6kW PowerOne inverter, about 6,000kWh/year generated
6 off Pylontech US3000C batteries, with a Sofar ME3000SP inverter
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