Bad month for solar generation

[GaryMG4]

December 2024 looks like being a really bad month for solar generation. In the first 4 weeks my 4kW array has generated 44 kWh or around £10 (FiT) well down on previous years.

 

[Gadget Geek]

I fared a little better here in the southwest; 66.4 kWh. December the 22nd was the best day at 6.3 kWh.

 

[Everest]

December 2024 looks like being a really bad month for solar generation

Yes - the damn Earth needs straightening up a few degrees. We've managed just 180kWh so far; best day was the 19th with 13.9kWh

 

[subfiver]

333kWh so far this month on the Costa Calida ...

 

[Bam Bam]

93.09 kWh for us in Oxfordshire. One unbelievably good day, the 9th. Two ok days, the 6th and 15th.

Apparently it was 67.61 kWh in December 2023 so that is a big improvement somehow!

East and West arrays so really drops off in December and January.

 

[T1 Terry]

The only thing that knocks the solar harvest around over this side at this time of yr, is the panel heat.
In days gone by when people connected their RV solar in parallel charging 12V flooded cell batteries, the charge would drop to near enough to zero in the middle part of the day because the max output temp would drop below battery semi charged voltage of around 14V, not coming good again until the sun angle was poor as it dropped toward the horizon.

The common fix these days is panels in series with an open circuit voltage and MPPT controller up in the higher voltage range and output capacity @ 20°C rating on the back of the panel, above the controller capacity in the middle of the day.
This method brings the peak harvest capacity up earlier in the day and holds that peak for longer, great for the winter and for running the air con during summer ..... the waste on good sun days is more than offset by the improved harvest on poor solar days....

T1 Terry

 

[Everest]

93.09 kWh for us in Oxfordshire. One unbelievably good day, the 9th. Two ok days, the 6th and 15th.

Apparently it was 67.61 kWh in December 2023 so that is a big improvement somehow!

Better than 2021 then... December 2021 was dullest for 65 years, total 26.6 hours

https://www.telegraph.co.uk/news/20...ullest-ever-just-266-hours-sunshine-recorded/

East and West arrays so really drops off in December and January.

Any room for some south facing ones too?

 

[Bam Bam]

Any room for some south facing ones too?

I'm starting to eye up the South-facing wall (side of house, above the garage).

Might be room for one or two on there, which could supplement the winter generation.

Have also been considering adding a room over the garage in the future, though, which would make some of that wall internal and the rest shaded. Any panels there would then have to be removed.

 

[Gadget Geek]

I think all of us with solar PV expect winter to be a poor season for generation. However, even as I type this on a dull, cloudy day, my panels are generating 400 Watts and the house is only using 200, the extra is trickling into the battery.

I've been looking at the stats for the year and my panels have generated a total of 3941.5kWh and the battery supplied 2891.8kWh. We've used 9681.2kWh of off peak, and 626.69kWh peak.

Putting all that together, without any solar or battery it would have cost us £2260.23! Adding solar and a battery brings it down to £1039.20, so well worth the investment.

 

[GaryMG4]

I agree about winter expectations, over the last 8 years we averaged around 3800 kWh annually with the winter quarter contributing around 500 kWh. I have been only noting the quarterly totals as FiT is paid quarterly. What has surprised me that for the whole of December just 51 kWh has been generated.

 

[Gomev]

I think all of us with solar PV expect winter to be a poor season for generation. However, even as I type this on a dull, cloudy day, my panels are generating 400 Watts and the house is only using 200, the extra is trickling into the battery.

I've been looking at the stats for the year and my panels have generated a total of 3941.5kWh and the battery supplied 2891.8kWh. We've used 9681.2kWh of off peak, and 626.69kWh peak.

Putting all that together, without any solar or battery it would have cost us £2260.23! Adding solar and a battery brings it down to £1039.20, so well worth the investment.

Wow, to me that is astronomic consumption. There are only 2 of us at home and have gas central heating so our seemingly low usage, , is making it hard, even nigh on impossible to justify investment in Solar and/or batteries even if I really really want to for other reasons.
Our total usage of electricity last year was 3305 kWh (less than your panels generated) costing a total of £664. That included charging overnight on Go

 

[Gadget Geek]

5 adults, 2 electric cars, electric induction cooker and a Tepeo Zero Emmission Boiler (although the ZEB has only been used these last couple of months as it was installed in August).

 

[Gadget Geek]

I just thought I would share this screenshot from the National Grid. I've not seen that much wind generation for such a long period before, nearly two thirds of the total generation.

 

[Everest]

What has surprised me that for the whole of December just 51 kWh has been generated.

The PVGIS website makes available a handy tool to work out expected generation for your specific location, orientation and angle of panels. This uses solar radiation data collected over about 20 years.

JRC Photovoltaic Geographical Information System (PVGIS) - European Commission

Photovoltaic Geographical Information System (PVGIS)

re.jrc.ec.europa.eu

 

[johnd973]

Ours managed 66kw for December for a 4kw array on a south west facing roof on the North Devon coast.

I'm fine with that kind of generation this time of year. We supplement this by charging the house batteries from the grid on cheap power overnight and we have a Ripple Wind Farm investment.

We're considering buying extra battery storage as we can buy power from the grid overnight all year round at a rate far below what we sell it for. Just got to do the maths to see if it is financially worthwhile given the cost of batteries and inverters.

All in we pay £45 a month to run an all electric house and an EV so we think our investment in renewables ( we have solar PV, solar thermal and a wind farm investment ) is paying us back very well

 

[Fokmg]

Yes December 2024 was certainly the worst December I experienced.
Solar panels face south (this sunny West Wales !!!)

December 23 was 104 KW
December 24 was 85.6 KW (82.3% previous year)

2023 was 5490 KW
2024 was 4810 KW (87.6% previous year)

On the bright side when we were without power for nearly 4 days in December due to storm damage we were able to keep the house running all the time due the benefit of 15Kw of solar and the Tesla Powerwall.

Very fortunate that the battery was able to keep the solar panels alive and was able to harvest 14Kw to go into the rapidly depleting battery!!!

Out of interest our total household consumption for 2024 was 13,763 KW !!!!!
We purchased 9154 KW (all bar 38 units at 7p/ unit (octopus go inteligent/ tesla power wall) .
The rest was from Solar power and we lost 39 units to export

Our effective cost per unit worked out at 4.7p for the year (excluding standing charge )

Total electric cost including tariffs was £864.37

Running the MG 5 is very low as we have only ever used our own cheap power!

 

[GaryMG4]

I've not been recording individual months (only FiT quarters) until recently, so I don't have a direct comparison it just felt very low at 10% of the average quarter. As it is the annual FiT payment is roughly the same as my annual electricity bill so I shouldn't complain. I'm just trying to gauge the benefit of adding a battery.

 

[Fokmg]

If you are without power for 4 days after a storm trust me the battery is very handy.
My battery and solar PV working with Octopus Go Intelligent saves me approx £2900/year
compared with buying my power at standard rate charge @25.9p/unit
I do use a lot of power for the house and car (13700 KWh)
Last year I only paid for 38 units at 25.9p the rest was all at 7p or free solar!
My tesla powerwall will store 27KWh of power and allow a continuous load of 10Kw with a peak of 14Kw. (this avoids me having to explain to she who must be obeyed what electrical items she can use at any time!). The battery/solar powers everything between 5.30Am and 11.30Pm. Then everything incuding the house runs on cheap power while the batteries recharge.
The powerwall also manages to accept the max delivery from the solar panels throughout the summer and does not need grid power unless the weather is very bad .

 

[EV convert]

To me your figures sound like hitting the bigtime.

Last month our array (8 x 235W panels with 10.8% efficiency) produced just 26kWh making it by far the worst month for generating we have had in the past 14 years. It was however, completely in-line with the rest of 2024 which produced a total of only 1708kWh - again the lowest we've ever recorded.

The best was 2022 which just topped 2,000kWh so needless to say, our MG4 does not run on solar power (at least not that generated at home ).

 

[PJWey]

Given the Sun being being low in the sky and out much less as well as covered by clouds and thick gloom it’s hardly surprising. Thankfully brighter days, weeks and months ahead. East facing 1.4kW array will do a little better then.