Solar panels and battery - any real world reccomendations?

A question for those with batteries, what sort of actual charging capacity are you getting compared to the claimed capacity?

I'm running 5x 2.45kW Fox Mira HV25s which should give me about 10.8kW capacity (from 12-100% SOC, so 88% of the 12.25kW total) but in reality it charges about 9.6kW and that's it?
 
reef said:
A question for those with batteries, what sort of actual charging capacity are you getting compared to the claimed capacity?

I'm running 5x 2.45kW Fox Mira HV25s which should give me about 10.8kW capacity (from 12-100% SOC, so 88% of the 12.25kW total) but in reality it charges about 9.6kW and that's it?
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Check the depth or discharge on your batteries. The smaller ones in particular typically may limit this to about 80% or so.

My GivEnergy 8.2kWh has a DoD or 100% so I have access to more or less all of it (reserve at 4%).
 
Depth of discharge is 90% on these and min SOC is set to 12% (lowest I can set is 10%) which is why I'm confused that I'm only getting 9.6kWh instead of 10.8kWh usable as you'd expect.
 
reef said:
A question for those with batteries, what sort of actual charging capacity are you getting compared to the claimed capacity?

I'm running 5x 2.45kW Fox Mira HV25s which should give me about 10.8kW capacity (from 12-100% SOC, so 88% of the 12.25kW total) but in reality it charges about 9.6kW and that's it?
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When you say it charges 9.6 is that grid draw or what you see from the battery
They are not 100% conversion in either direction

If you achieve 9.6 output then your probably within the region of conversion being the main issue
 
The 9.6kWh figure is the amount the batteries will take when charging from the panels from the minimum SOC of 12% to 100%.

I'm wondering if its a reporting issue as the output is slightly higher than this. e.g on the 7th and 8th March the combined charging was reported as 11.1kWh, but the batteries discharged 12.3kWh. This is from 12% on the morning of the 7th to 12% again late-evening on the 8th.
 
For measuring electricity usage i get data from the CT clamp, and use the API from Octopus in home assistant it's pretty accurate. I think IHD is largely needless these days no?
 
It isn't an exact science, and also depends how they're working out the SOC, if it's by voltage then that's very inaccurate, must reliable way is to count the amps in and back out, but that also can be inaccurate.

In my Victron system the cells reach a certain voltage, then the voltage is kept constant and the amps drop off, I have absorption period set to two hours, by that time the current is getting low and the cells are fully absorbed. The battery may well show 100% before this period is fully up, if the sun stops shinning then the cells may not be completely full, how much difference it makes I'm not sure.

My battery is about 14.5kWh, but that would mean using the full voltage range of 2.5v to 3.65v per cell, I run from around 2.9 to 3.55 IIRC, so a little power is not used, again not sure how much difference it makes.
 
My ****show solar panel saga finally ground to halt today. Quick recap - gave the go ahead for an install over six months ago, discovered in January(!) that the company hadn't submitted a DNO application, persevered and told them to crack on with it. Today I was told that because I hadn't paid in advance for it (I was told it was all included in the final invoice once install was completed) that the DNO application still hadn't been sent. So I told them where to go... This is from a supposedly professional company too!

By coincidence I had another company out today to provide a quote as I've been rapidly (and rightly as it turned out) losing confidence with the initial company. Seemed a hell of a lot more professional and knowledgable than the first company so we'll see what the quote is like.
 
Bluecube said:
My ****show solar panel saga finally ground to halt today. Quick recap - gave the go ahead for an install over six months ago, discovered in January(!) that the company hadn't submitted a DNO application, persevered and told them to crack on with it. Today I was told that because I hadn't paid in advance for it (I was told it was all included in the final invoice once install was completed) that the DNO application still hadn't been sent. So I told them where to go... This is from a supposedly professional company too!

By coincidence I had another company out today to provide a quote as I've been rapidly (and rightly as it turned out) losing confidence with the initial company. Seemed a hell of a lot more professional and knowledgable than the first company so we'll see what the quote is like.
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Not good admin at all but not surprising. Some equipment prices have come off a bit so may be good to get another quote. To be honest you can just connect and notify. If over 3.68kw you can still limit, connect and notify.
My approval came through about 6 months after my install.

https://forums.overclockers.co.uk/t...-world-reccomendations.18946524/post-36087265
 
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So after having two companies quote and give me a price of around £15k for an 8 panel, 9-10kwh battery system I have got a third company out to quote:

  • Solis 3.6KW Hybrid Inverter
  • 2 Puredrive DC Battery 5KWH
  • 9 JA Solar 500W Jam66S-30-500-MR Panels
  • Solic 200-wireless
  • Emlite Gen Meter
  • Installation, supply and scaffolding of the above, including birdproofing
The quote for the above comes to £11,979 which to me seems far more reasonable than the other two quotes, plus its a 4.5kWp system as opposed to the 3.6 i was being quoted for before.

Thoughts from those more experienced?


I think Essex seems to generally be more expensive than other parts of the country based on the quotes i have been getting.
 
Wegason said:
So after having two companies quote and give me a price of around £15k for an 8 panel, 9-10kwh battery system I have got a third company out to quote:

  • Solis 3.6KW Hybrid Inverter
  • 2 Puredrive DC Battery 5KWH
  • 9 JA Solar 500W Jam66S-30-500-MR Panels
  • Solic 200-wireless
  • Emlite Gen Meter
  • Installation, supply and scaffolding of the above, including birdproofing
The quote for the above comes to £11,979 which to me seems far more reasonable than the other two quotes, plus its a 4.5kWp system as opposed to the 3.6 i was being quoted for before.

Thoughts from those more experienced?


I think Essex seems to generally be more expensive than other parts of the country based on the quotes i have been getting.
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I’d personally probably be tempted to go for a bigger inverter - I’d go for 5kw as even if the panels can’t reach that alone, the batteries or batteries + solar can and you won’t get any clipping at peak generation.

Downside is more expense and probably a G99.
 
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At 4.5kWp (and depending on panel orientation) it's not insanely under-sized, the systems that are like 6kWp+ with only 3.6kW inverters are way more tragic.

I'd gun for more panels if you can get them up though.
 
reef said:
Depth of discharge is 90% on these and min SOC is set to 12% (lowest I can set is 10%) which is why I'm confused that I'm only getting 9.6kWh instead of 10.8kWh usable as you'd expect.
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Are they indoors?

If not, might be temperature related perhaps? Being cold reduces capacity, it varies but most won’t be operating at peak performance unless around 20-30 degrees (internally at least).
 
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HungryHippos said:
At 4.5kWp (and depending on panel orientation) it's not insanely under-sized, the systems that are like 6kWp+ with only 3.6kW inverters are way more tragic.

I'd gun for more panels if you can get them up though.
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Yeah not particularly undersized for the panels, but those batteries can happily support a 5kw output all by themselves… so you’d be leaving a potential 1.4kw of power untapped when the batteries are there to support the load.
 
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Yeah maybe get a bigger inverter for internal, but you could forego the G99 at that level I think.

Limit the inverter to 3.6kW export whilst leaving you with an internal 5kW inverter capacity.
 
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Some general solar questions just for your opinion and to help my understanding. At the moment I only have a puny 2kW system with no batteries.

cnxYdgt.jpg


Current system:

2kW setup
8 x 260W panels Trina Honey TSM-PC05A (reading online Trina are a really good brand)
2.6kW Inverter

My general questions:
  • Are solar panels hot swappable - in that I can buy some 500W ones and have an independent engineer swap them out right out? Unscrew old, plug in new? A quick fix to boost my power (even though my inverter might be too weak)
  • I see some 500W-540W panels for £150 approx (https://www.zerohomebills.com/product/ja-solar-jam66s30-500-mr-500w-solar-panel/). Any opinions on these new 500w panels? First time i've seen them hit the market
  • See the roof: Do you think that instead of replacing the 260w panels I should get a company to install 4/5 *more* 500w panels around the edge boosting my generation that way? Or see about swapping the original 8 and maybe adding more 500w. Perhaps squeezing 7 more panels around the sides to give a total of 7500w but this may be overkill
  • Am I correct in thinking that I will lose my FIT if I change my system? I'm not that fussed because really I get something like £15 a quarter - it doesn't generate a lot and we use a lot in the day.
  • If I heavily add to this system will I need to fill out one of those forms for going over 3.6kW or are those only if you intend on giving back to the grid? Part of me is considering just filling my own batteries and forgetting the grid
  • My inverter would be way too small so the suggested upgrade would be to 5kW?
 
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HungryHippos said:
Yeah maybe get a bigger inverter for internal, but you could forego the G99 at that level I think.

Limit the inverter to 3.6kW export whilst leaving you with an internal 5kW inverter capacity.
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This is what I would do also in your situation. Good future proofing and will allow you to get the most out of your system and any batteries today or added in future.
 
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