1. Batteries 2. PV comparison

[Garald]

1. A PV installer visited today. We talked a bit about batteries. He said, basically - it's not worth installing batteries today (from a cost/efficiency or environmental perspective), there will be some that are worth it in the future, actually, they already exist, but we want to make sure they work well before offering them, etc. Perhaps more to the point, he said that I should have no difficulty installing batteries in 5 or 10 years time, as one can just plug them into the main, and charge them with the electricity produced by whatever I install now. Is this how it works?

 

(For context - here one sells excess electricity produced by solar panels at half the price one has to pay to buy electricity.)

 

2. I am getting three very different offers. Two are more or less in the same range - I am attaching the technical information for one of them (the other one is from IKEA - they'll send me more precise information letter). The third offer, from a large state-owned energy company, costs about twice as much (technical information sheet attached as well). Said the installer (same as the one above): we don't have the least expensive or the most expensive solar panels in the market, our products will last 30 years, our panels are two-sided, our panels are just better, our panels are French rather than Chinese, etc.

 

The two panels look very similar to me. Anything I am missing? (Can you guess which one is the one that costs twice as much as the other one?)

 

(And yes, guess what, the panels from the less expensive supplier are also French.)

fiche dualsun 425 (1) (1) (1).pdf PW54M10-BB 425W FR Définitive.pdf

[SteamyTea]

I suspect that you would never notice any difference between the two systems.

 

There is an awful amount of nonsense spoken by salespeople.

 

I do agree about the batteries though, it is still early days for them and they are sold to boost the profitability of the company, not to really help the consumer.

 

Many years ago there was a small domestic wind turbine that just plugged into a wall socket. While it is fairly easy to design a system like that, it is probably not the best way of doing it.

[Cooeyswell]

I came to this from the opposite direction.

I need power 24/7, 365 days per year.

Where I live PV is pretty much a non-event for 3 months of the year and marginal for another two. (I would do a lot better with wind energy but its not acceptable to the planners.)

E7 electricity is available at reasonable cost 365 days per year.

I therefore installed a 15kWh battery system charged from E7 (no solar at all), including the inverter this was <£3k.

This moves almost all my entire electricity consumption to off peak. Payback time is around 4 years.

Given this as a starting point, If I then work out whether it makes sense to add PV to the system the answer is pretty much no.

Don't assume that a battery must be an add on to PV. Consider PV as an add on to a battery and do the maths - you may be surprised.

 

As for the environmental story - The off-peak period has a lot more renewables/nuclear in the mix so there is likely to be a net CO2 reduction compared to raw electricity usage.

 

[Garald]

6 hours ago, Cooeyswell said:

 

As for the environmental story - The off-peak period has a lot more renewables/nuclear in the mix so there is likely to be a net CO2 reduction compared to raw electricity usage.

 

 

Well, this is France: there's lots and lots of nuclear (86.9% of EDF's production), one can pay a company a bit extra to ensure that one is consuming only renewables 'but are they telling the truth?), there are renewables-only companies (I am considering switching to one of those), etc.

 

Does the battery system just plug into the mains? Link? What is the efficiency? Since the price I get for selling electricity to the network is half of the peak price of consuming electricity off the grid, consider the no-battery option as being equivalent to a free battery operating at 50% efficiency.

Edited May 4 by Garald

[SteamyTea]

9 minutes ago, Garald said:

one can pay a company a bit extra to ensure that one is consuming only renewables 'but are they telling the truth

They will almost certainly be selling the same volume of electricity as they are buying in, so in accountancy terms, yes they are truthful.

In reality, the electrons go to the closest load first, so in Physics terms, no they are not.

 

As it is really about reducing CO₂, it does not matter as it is the fraction of the whole that is important, not the sum of one component.

 

You can see what is happening here.

https://www.gridwatch.templar.co.uk/france/

It shows that other countries are taking/adding as well.

[Cooeyswell]

7 hours ago, Garald said:

 

Well, this is France: there's lots and lots of nuclear (86.9% of EDF's production), one can pay a company a bit extra to ensure that one is consuming only renewables 'but are they telling the truth?), there are renewables-only companies (I am considering switching to one of those), etc.

 

Does the battery system just plug into the mains? Link? What is the efficiency? Since the price I get for selling electricity to the network is half of the peak price of consuming electricity off the grid, consider the no-battery option as being equivalent to a free battery operating at 50% efficiency.

 

The inverter/charger connects into the mains, the battery connects into the inverter.

I use a Solis inverter (https://www.solartradesales.co.uk/solis-3-0kw-5g-rai-energy-storage-ac-coupled-battery-charger)

and a Seplos battery kit (https://www.fogstar.co.uk/collections/seplos-mason-kits/products/seplos-mason-280l-and-x16-grade-a-eve-lf304k-battery-bundle)

Prices and supply vary but deals can be had with a bit of patience.

My calculated round trip efficiency is somewhere between 80-90%. Off-peak electricity is currently ~40% of peak price,

[JamesPa]

1 hour ago, Cooeyswell said:

 

The inverter/charger connects into the mains, the battery connects into the inverter.

I use a Solis inverter (https://www.solartradesales.co.uk/solis-3-0kw-5g-rai-energy-storage-ac-coupled-battery-charger)

and a Seplos battery kit (https://www.fogstar.co.uk/collections/seplos-mason-kits/products/seplos-mason-280l-and-x16-grade-a-eve-lf304k-battery-bundle)

Prices and supply vary but deals can be had with a bit of patience.

My calculated round trip efficiency is somewhere between 80-90%. Off-peak electricity is currently ~40% of peak price,

That good value and simple (in a good way).  It looks like it needs a dedicated 32A connection.  Did you get a sparky to do that and self install the rest.  I can't remember if a battery needs dno permission

[Cooeyswell]

5 hours ago, JamesPa said:

That good value and simple (in a good way).  It looks like it needs a dedicated 32A connection.  Did you get a sparky to do that and self install the rest.  I can't remember if a battery needs dno permission

Yes it does require a 32A connection - I had a high current feed put in for the garage when I built the place, so not a big issue for me - Just another MCB on the CU.

Luckily I live in one of the civilised parts of the UK where part-P was never implemented so the system was entirely self installed. If you are unluckily enough to live elsewhere then a sparky would be required for the final hookup.

You do need to inform the DNO but it comes under G98 provision, so you don't need permission to install but you do need to inform them after the fact.

 

As an aside I have just received a flyer in the mail for a PV install (3.6Kw) for £4k. This gives a 10Yr-ish payback with my usage/location, which is marginal in my book but a lot better than the £7k I was previously quoted.

Edited May 4 by Cooeyswell

[JamesPa]

13 hours ago, Cooeyswell said:

You do need to inform the DNO but it comes under G98 provision, so you don't need permission to install but you do need to inform them after the fact.

Thanks.  I've already got 3.68kW PV under g98.  I was thinking that this ac coupled battery solution was a low cost simple add on but I think the dno regards it as a separate generator thus requiring G99, although it's clear that both would not be generating simultaneously.  Does anyone know whether I'm right or not?

[JohnMo]

1 hour ago, JamesPa said:

but I think the dno regards it as a separate generator

They do.

 

I suppose they think, at say 3pm, batteries are full, PV generation doing 3.68kW, you then go into dump mode to the grid from the battery. To get paid for the total exports. Daft but some may do it.

[Garald]

16 hours ago, Cooeyswell said:

Yes it does require a 32A connection - I had a high current feed put in for the garage when I built the place, so not a big issue for me - Just another MCB on the CU.

Luckily I live in one of the civilised parts of the UK where part-P was never implemented so the system was entirely self installed. If you are unluckily enough to live elsewhere then a sparky would be required for the final hookup.

You do need to inform the DNO but it comes under G98 provision, so you don't need permission to install but you do need to inform them after the fact.

 

As an aside I have just received a flyer in the mail for a PV install (3.6Kw) for £4k. This gives a 10Yr-ish payback with my usage/location, which is marginal in my book but a lot better than the £7k I was previously quoted.

 

Uh. I wonder whether one can get a deal like that in the Paris area. The lowest quote I've got is 7181 eur ( = 5681eur + 1500eur for the installation) for 3kW. (Then there's a 10% tax and a subsidy that will cover the tax if I'm lucky.)

[Garald]

Is it easy to program the battery so that it charges only when the solar panels are producing a surplus?

[JohnMo]

1 hour ago, Garald said:

Is it easy to program the battery so that it charges only when the solar panels are producing a surplus?

Yes, you house will almost use anything first anyway.

[sharpener]

On 05/05/2024 at 11:35, Garald said:

Is it easy to program the battery so that it charges only when the solar panels are producing a surplus?

 

We have PV, immersion heater diverter (home made), Zappi EV charger and a battery. Pecking order for the PV generation is by default (and is the same for most systems):

1. House loads
2. Charge battery
3. Immersion heater
4. Zappi
5. Export

The only time I need to change this is when I need both the car and hot water. Then I turn off the immersion temporarily so the car has first dibs, this is bc it requires a minimum power of 1.4kW.

 

In the afternoon when the PV drops below 1.4kW I can turn the immersion back on and still make use of the sunlight. If I charged the hot water first it would go to waste.

 

My legacy 3.68kW solar inverter is behind the battery inverter so the DNO considers them as one. The newer 3.2kW PV is connected via a DC-DC converter straight into the battery so the DNO doesn't consider it at all.

[Dave Jones]

saying its not worth installing batteries is like saying not installing a sink as you can use a bucket. same with a 5k kitchen and a 55k kitchen.

 

It's all 100% subjective.

[JamesPa]

15 hours ago, sharpener said:

My legacy 3.68kW solar inverter is behind the battery inverter so the DNO considers them as one. The newer 3.2kW PV is connected via a DC-DC converter straight into the battery so the DNO doesn't consider it at all.

That sounds interesting.  I am struggling to find a cost effective way to expand and/or add batteries to my 4kWp array fitted in 2011.  Without a doubt it's possible, but finding a way to isolate an add on that someone is interested in quoting for is proving challenging, most want to rip it all out and start again.

 

Have you by any chance got a circuit/bloch diagram of your set up?

[Dillsue]

Assuming your existing is a FIT system?, look up the OFGEM guidance for FIT generators and either the guidance for generators(you or me) or FIT payers(electric Co.)  includes schematics on allowable configurations for battery hook up. Basically it mustn't be possible to charge the battery from the grid and then discharge through the FIT Generation meter. Only site generated eleccy from your acredditted system can pass through the generation meter.

 

DNO requirements are separate so an AC coupled battery downstream of your generation meter will likely meet with FIT rules but need G99 approval  from your DNO

[Garald]

54 minutes ago, Dillsue said:

Assuming your existing is a FIT system?, look up the OFGEM guidance for FIT generators and either the guidance for generators(you or me) or FIT payers(electric Co.)  includes schematics on allowable configurations for battery hook up. Basically it mustn't be possible to charge the battery from the grid and then discharge through the FIT Generation meter. Only site generated eleccy from your acredditted system can pass through the generation meter.

 

I don't have an existing system yet! I take FIT is about selling energy back to the state at regulated prices? Yes - this is all in France - the price offered is not terrible and not great (about half of peak prices for consumption).

 

Here's the quote I'll probably accept (with one controller for every two panels). I should make my decision today or tomorrow (or else I won't take advantage of a discount). The main alternative is IKEA - they are about to call me, but I take it would be at least 2000eur more.

devis_DEV-28851_28851.pdf

[Dillsue]

Sorry, replying to JamesPa!!

[JamesPa]

3 hours ago, Dillsue said:

Assuming your existing is a FIT system?, look up the OFGEM guidance for FIT generators and either the guidance for generators(you or me) or FIT payers(electric Co.)  includes schematics on allowable configurations for battery hook up. Basically it mustn't be possible to charge the battery from the grid and then discharge through the FIT Generation meter. Only site generated eleccy from your acredditted system can pass through the generation meter.

 

DNO requirements are separate so an AC coupled battery downstream of your generation meter will likely meet with FIT rules but need G99 approval  from your DNO

Thanks

 

I looked at the guidance, there are a lot of options!

 

Practically speaking I have a generation meter and a smets2 smart meter.  I think the latter does net metering so I think that covers it for most of the likely configurations.  I would check with my supplier first anyway (Octopus), always assuming I can eventually get a sensible quote!

[sharpener]

44 minutes ago, JamesPa said:

I think the latter does net metering so I think that covers it for most of the likely configurations. 

 

No, they have a separate export register but AIUI you will have to get Octopus to apply to yr DNO to allocate a separate MPAN to use this. Have PM'd you also.

[JamesPa]

5 minutes ago, sharpener said:

No, they have a separate export register but AIUI you will have to get Octopus to apply to yr DNO to allocate a separate MPAN to use this. Have PM'd you also.

Thanks. I think that's already done as I'm on metered export not deemed (possibly a mistake given my recent acquisition of an electric car), and my bills seem to have several mpans already.

[Dillsue]

14 minutes ago, JamesPa said:

Thanks. I think that's already done as I'm on metered export not deemed (possibly a mistake given my recent acquisition of an electric car), and my bills seem to have several mpans already.

I have long been under the belief that you can choose metered or deemed and could revert to deemed if you wanted to. Dont know where I've got that from but may be worth looking into. Deemed is certainly the way to go if you'll be daytime charging a car or battery

[sharpener]

34 minutes ago, Dillsue said:

I have long been under the belief that you can choose metered or deemed and could revert to deemed if you wanted to.

 

No, as frequently discussed on this board you cannot go back to deemed once you have left, it is irreversible. Which is why I am keeping my FIT payments on deemed until I see how the combo of EV and HP works out.

 

My deemed export is 2MWh/yr worth £960. Actual exports in the last 12 months were 2.756 MWh, that is after the EV but before the HP is installed. So it might drop quite a lot as I am expecting there will in future be little or no export in winter. Or if I use the HP all year round instead of the immersion diverter it might go up in the summer and balance out. Also it is far from optimised as I have an export limit of 16A otherwise right now I would be sending nearly 5kW to the grid.

[Dillsue]

1 hour ago, sharpener said:

 

No, as frequently discussed on this board you cannot go back to deemed once you have left, it is irreversible. Which is why I am keeping my FIT payments on deemed until I see how the combo of EV and HP works out.

Not sure that's necessarily correct! If you add PV in addition to your FIT system it's not possible to use metered export as there's more going through the meter than just FIT export. What you are saying is that export payments would then end??