Solar + battery - battery capacity nowhere near stated, installer does not want to know

kgrins

Hi,

I did post some of this in the Green & ethical MoneySaving sub-forum but here I am more looking for consumer rights information.

What did you buy?     When did you buy it?

We had a solar and battery system installed back in February 2023.

Where from? (internet or in store - it DOES make a difference)

The system’s components were all supplied and chosen by the installer.

How did you pay? (cash/cheque/debit card/credit card etc)

Unfortunately, we paid by bank transfer.

What went wrong?

While there were other issues, the main problem is that the battery system’s capacity falls way short of we were sold and paid for. Often it is less than half of the stated capacity.

In effect we paid for 10 kWh of battery but have had at most half of that.

More on how we calculated how far below expectation our system performs later.

What are the vendors telling you?

The vendor basically does not want to know.

We went down arbitration route as the installer / vendor are a member of some of the solar installation certification bodies. We tried MSC, NAPIT, and HIES

We got no useful response from all three that we tried.

MSE – probably the best known in the industry as without their cert consumers cannot sell their exports – basically did not want to know and said while our installer is registered with them, they were only registered for solar installations not batteries. Of course, our installer plastered the MCS logo all over their website and so on without any caveat.

NAPIT did at least get our installers to fix issue their electrician had left which resulted in Octopus’s smart meter installers refusing to install a new meter – since NAPIT are a competent person’s register if we had reported our installer to building control, we would probably have had the similar results.

Finally, HIES were by far the worse. The agent dealing with our complaint immediately took the installers side and said things like any such problem is with manufacturer. Aside from the manufacturer having no relationship with us – as I said earlier the installer chose and supplied every part of the installation – we feel that the HIES agent displayed total ignorance of sales of good /services.

That was all a long time ago with HIES closing our complaint in August.

What we are looking for?

Well, to have a system whose battery comes somewhat near to the sold capacity.

Failing that – and if we had paid by credit card this is probably what we would be demanding – for our installer to take back their batteries and refund us that part of the installation.

Basically, we have reached a standstill with this and are looking for advice.

Should write our installers a final letter using various wording from the Sales of Goods Act and the Consumer Rights Act 2015? Certainly, the goods supplied, specifically the battery system, are not fit for purpose, nor as described.

If we were to be forced to down the small claims courts route, would the HIES “arbitration” siding with the installers hinder us? That is, would our installer just have to make it all look very technical and the court could then say we cannot proceed?

We have looked if we could find a solar installer/engineer who could provide us with a report but have not had any luck.

How we arrived on at our figures for the battery system

Our inverter logs, the web portal for the inverter, the logs from Octopus all agree: our batteries do not provide anywhere close to their rates specs.

Initially we had based everything on rundown from the inverter logs as the inverter should know and record what is happening. HIES and our installer dismissed those figures as being the wrong way to do this – but gave no suggestions on how the system can be measured.

Later, after looking at some forum posts, we change our approach to discharge the battery down to its min and then charging it from the mains.

Plus, we now have the Octopus smart meter which can give us an accurate breakdown of how much we imported from the grid during the time it took to charge the battery.

All three method give us roughly the same figures. Our battery system which holds 10 kWh, charges from min (10%) to full drawing around 3 to 3.6 kWh rather than the expected 9.0 kWh or more. We have not invented perpetual motion as the discharge power agree with the under 4 kWh figures.

the_lunatic_is_in_my_head

Hello OP

After 6 months burden of proof sits with the consumer if there is an issue with goods.

If the batteries were not itemised cost wise it’s a transfer of goods covered by services under the CRA and I believe burden of proof might sit with the consumer in any case there.

If you can get an independent inspection with some something credible on paper the company should repair or replace*, if they don’t within a reasonable time (possibly there already) then you can reject for a refund minus use. 

Letter before action followed by small claims of no agreement can be made. 

*If the batteries weren’t itemised then it’s repeat performance within a reasonable time and then price reduction for the benefit of the service you haven’t received, pretty much the same thing but if you do end up in small claims best to get everything correct.

SOGA won’t apply as the CRA now covers this for consumers, fit for purpose covers a specific purpose you ask about. 

Not matching the description  would be best and simplest option  

forgotmyname

How much power is lost at the inverter?   How much power are you pulling from it when testing?  Is the battery charging 100%
which is may not to help the battery live longer.  Maybe a setting to increase the charge value.

If it only charges to 80% for long battery life your losing a fair bit of capacity but it should live longer.

What batteries?  What does the labels show and how many?

born_again

I would have said go back to manufacture & get them to come & check the batteries.

Yes I know that they have no part other than supplying to installer. But they are the ones who can check & resolve the issue if the batteries are the issue & not some setting or other issue with the install.

TELLIT01

I agree with born_again that you should approach the manufacturer and ask them what the 'real world' performance of the batteries should be.  There is a difference between the test conditions under which the spec is created and the variables of the real world.  A bit like car fuel consumptions figures!

kgrins

the_lunatic_is_in_my_head said:

Hello OP

After 6 months burden of proof sits with the consumer if there is an issue with goods.

If the batteries were not itemised cost wise it’s a transfer of goods covered by services under the CRA and I believe burden of proof might sit with the consumer in any case there.

If you can get an independent inspection with some something credible on paper the company should repair or replace*, if they don’t within a reasonable time (possibly there already) then you can reject for a refund minus use. 

Letter before action followed by small claims of no agreement can be made. 

*If the batteries weren’t itemised then it’s repeat performance within a reasonable time and then price reduction for the benefit of the service you haven’t received, pretty much the same thing but if you do end up in small claims best to get everything correct.

SOGA won’t apply as the CRA now covers this for consumers, fit for purpose covers a specific purpose you ask about. 

Not matching the description  would be best and simplest option  

Thanks for that.

A pity we let this all slide back in August but at that stage I was really tired after pouring over logs for ages and getting nowhere - especially with that so-called "regulator".

Of course, when we first complained that things were nowhere near to what we were sold it was far closer to 6 weeks after the install - it was just by not taking us seriously the installer was able to drag it all out.

The batteries are and aren't an itemised costs: the initial paper work was for one 5.15kWh battery:

but we asked about the cost of another, and the quoted and supplied a second one:

So the battery system was  2 x £2,000 in the end for parts. That the battery was an Pytes 48R100C is not mentioned although 5.12kWh does narrow things down somewhat.

As for getting an independent report on the state of the battery system: that has proved tricky. It seems no installers want to sell that as service.

forgotmyname said:

How much power is lost at the inverter?   How much power are you pulling from it when testing?  Is the battery charging 100%
which is may not to help the battery live longer.  Maybe a setting to increase the charge value.

If it only charges to 80% for long battery life your losing a fair bit of capacity but it should live longer.

What batteries?  What does the labels show and how many?

Well, from what I can gather from the inverter's logs, the figure for [Daily Charging Energy(kWh)] (as it calls it) is how much it has "pushed" to the battery system. What it pulls from the grid for that is a separate figure. The inverter claims 97% efficiency but doesn't break down its varies efficiencies (at converting DC from the solar grid, at converting AC from the grid, etc.).

The battery on the other hand says it is 95% efficient at being charged.

As for 100% vs 80%, I would hope that the BMS on the battery would have some over-provisioning. That is the cells could hold X amount of mAh when charged to Y voltage, but that it doesn't go up that limit. The whole Pytes battery is rated for 6,000 charge cycles as it is a LFP (aka LiFePO4) battery rather than the older Lithium Ion ones.

The batteries are 2 x Pytes 48R100 C

https://www.pytesgroup.com/product-detail/&122

So each rated at 5.12 kWh for a total of 10.24 kWh.

born_again said:

I would have said go back to manufacture & get them to come & check the batteries.

Yes I know that they have no part other than supplying to installer. But they are the ones who can check & resolve the issue if the batteries are the issue & not some setting or other issue with the install.

Not even sure if they have a UK representative. I have tried emailing twice now, but no response.

The European distributor is in NL but only has a telephone contact. Maybe I should try calling them although they would be well within their rights to say I have nothing to do with them.

TELLIT01 said:

I agree with born_again that you should approach the manufacturer and ask them what the 'real world' performance of the batteries should be.  There is a difference between the test conditions under which the spec is created and the variables of the real world.  A bit like car fuel consumptions figures!

Pytes are by far not the most common battery / energy storage supplier, but I have since discovered that a number of people on the DIY Solar forum did test them.

If we were talking about 5% to 10% I would agree, but what we are seeing is more like 30% to 40%. I did not mention it in the OP, but I have tested the batteries individually and both perform about 30-40% of their individual rated capacity when tested one by one.

forgotmyname

The battery does not hold 10KW.   The battery should be able to output 10KW max.

They have a rating of 100Ah.   Ignoring losses and temperature etc.   2 x 5KW batteries will output 5KW or 10KW.
You will get more than twice as long a runtime with a 5KW output than a 10KW output.

Recommended discharge current is 50% of their rated value so the 10KW output should be more like 5KW continuous.
Maximum charge/discharge is 100amps which is where the 5KW / 10KW comes in.

They have a nominal capacity of 100Ah but they don't appear to show at what test rate?  Having a super low load when testing
can give an artificially high AH rating.


Imagine a pair of 12v batteries a 100Ah and a 60Ah IF tested using the same 20Amp load. The 100Ah lasts 5 hours and the 60Ah lasts 3 hours.

I want to glorify the cheaper batteries specs.  So I test the 100Ah at 20amps and the 60A at 1amp, the reduced load gives an extended
runtime for the smaller battery making it appear better. Hence the 20Ah rating on many batteries.
A 100Ah battery run at 1amp rather than 100Amps is likely to last more than 100x longer.

A rather simplified explanation but does that make sense?   They don't appear to have their testing procedures with voltages/current drawn.

PragmaticMoneySaver

forgotmyname said:

The battery does not hold 10KW.   The battery should be able to output 10KW max.

The OP didn't say 10kW, they said 10kWh

They have a rating of 100Ah.   Ignoring losses and temperature etc.   2 x 5KW batteries will output 5KW or 10KW.
You will get more than twice as long a runtime with a 5KW output than a 10KW output.

No, they won't!  The standard and max discharge for the battery is approx. 2.5kW (50A @ ~50v) according to the spec sheet.

Recommended discharge current is 50% of their rated value so the 10KW output should be more like 5KW continuous.

Each battery is different, as said the spec sheet states 50A for this battery.

Maximum charge/discharge is 100amps which is where the 5KW / 10KW comes in. No it isn't

They have a nominal capacity of 100Ah but they don't appear to show at what test rate?  Having a super low load when testing
can give an artificially high AH rating.

Imagine a pair of 12v batteries a 100Ah and a 60Ah IF tested using the same 20Amp load. The 100Ah lasts 5 hours and the 60Ah lasts 3 hours.

I want to glorify the cheaper batteries specs.  So I test the 100Ah at 20amps and the 60A at 1amp, the reduced load gives an extended
runtime for the smaller battery making it appear better. Hence the 20Ah rating on many batteries.
A 100Ah battery run at 1amp rather than 100Amps is likely to last more than 100x longer.

A rather simplified explanation but does that make sense?   They don't appear to have their testing procedures with voltages/current drawn.

A modern LFP battery will give it's specified output right down to pretty much empty - the BMS will likely prevent total discharge and usually they stop at about 10%.  

In the case of the OP, it does seem as something isn't correct - maybe the BMS hasn't been correctly configured for the extra battery and so it is only using 1 of the OPs two batteries.