A question about Solar Panel equipment types

[Jaded]

We are looking at an installation for a community building I am involved with.

We have had a number of quotes, and I was intrigued to see that there was such a spread of manufacturers for panels, inverter and batteries.

Panels	Inverter	Battery
Evolution 455w		6kW Evolution
Hyundai 450w	Growatt	Growatt 6.5kw
Longi 405w	Giv Energy 5kw	Giv 9.5 kWh
Trina 425w	Solis 5kw	5kw Puredrive
Longi 410w	Sunsynk 8,000kW	Sunsynk 5.12kWh

Are they all similar, or are there brands to avoid?

[Mrs Pingu]

Dunno a lot about about avoiding but Giv, Growatt and Puredrive, (our inverter is a solis) all seem to be widely used. Quite a spread of inverter size and battery size, what size of array are you going to have and what sort of use pattern?
I can recommend Gary Does Solar on YouTube as a useful beginners resource.

As a data point our 5kWh battery only takes a couple of hours to charge on a sunny day.

[Jaded]

We would be looking at just above 5kw panel array. So maybe 12 panels. Usage is mainly evenings, hence the battery as part of the install.

[HTFB]

If you are getting solar panels then a 4 to 6kWh battery will pay for itself in no time. It's not worth adding a second one, because in the winter it will never get charged and in the summer it will never get drained.

I think we have ended up with Trina panels, but after the installers screwed up the installation we kicked up such a righteous fuss that although we got replacement panels all subsequent interactions have been through the roofer and I'm not sure. For panels the brand didn't seem to matter much. We have a Growatt inverter and battery.

[Mrs Pingu]

I think the battery drainage very much depends on what you are doing with it. If it's a community thing rather than a home or could be quite different.
Jaded if you have any idea on what the usage  looks like over the course of the day Vs evening this may help you.

[aidan.f]

Basic maths, a 9.5 kWh battery will store about £3 worth of electrickery assuming 35 p/kWh. So that's your maximum daily saving for simple energy demand shifting*. In winter time you maybe able to charge overnight at cheap rate and use daytime/evening. You should really know your peak time and base loads ( fridges freezers) which can/will be a significant battery drain.
*Octopus agile is a whole different game that I know little about but maybe better in your usage scenario - is the hall occupied every evening and will you use the energy?

[aidan.f]

Is the hall single phase? If so I could lend you an energy monitor but it's not a consumer product, (EmonPi) If not single phase it gets more  complicated...

[Jaded]

If you are getting solar panels then a 4 to 6kWh battery will pay for itself in no time. It's not worth adding a second one, because in the winter it will never get charged and in the summer it will never get drained.

That's really helpful, thanks.

Is the hall single phase? If so I could lend you an energy monitor but it's not a consumer product, (EmonPi) If not single phase it gets more  complicated...

OK. I believe it is single phase. Thanks for the offer of the loan, but afaik we have a smart meter, although it is challenging to get the data out usably. I think I need to take a look at it!

I think the battery drainage very much depends on what you are doing with it. If it's a community thing rather than a home or could be quite different.
Jaded if you have any idea on what the usage  looks like over the course of the day Vs evening this may help you.

Pretty sure the usage is mostly evenings, and not every day. We have installed LED or other low usage lights. The heating is gas, which will present its own issue when the boiler shuffles off. All the installers quoting have made estimates of savings on usage and they average out at about 80%.

We have an odd situation in that one of the users of the building has their own meter (so we could install 2 systems) and has a much higher energy use. They wouldn't benefit from a battery, from what we can see, as most of their use is machinery during the day. They would pay for their install, and we would host the panels on our roof.

For what's it is worth, the  Trina : Solis : Prodrive option is the cheapest, and is a local company, so we are looking favourably at that one.

We have some scaffolding up at the moment for window replacement, so are looking at the economics of keeping some up and taking a hire extension fee as against a one-off scaffold to put the panels on. Also are getting structural survey advice (had recent roof surveys as we have a Circus School that wanted additional trapezes, so we had a survey and strengthening fitted)

[aidan.f]

Jaded,

Quote from: Mrs Pingu on Yesterday at 08:11:22 pm
I think the battery drainage very much depends on what you are doing with it. If it's a community thing rather than a home or could be quite different.
Jaded if you have any idea on what the usage  looks like over the course of the day Vs evening this may help you.

All the installers quoting have made estimates of savings on usage and they average out at about 80%.

80% of what? your total annual use? summer use? - IME a quote will be based on panel size X, battery size Y, average domestic consumption Z. I would encourage you to get some of your own figures. Just a MK1 pencil and paper, note the meter reading when hall opens up in the evening and closes up afterwards. From that you can work out evening and daily base load.  Obviously it's going to be more in the winter, more lights and heating uses some power to pump water.

As mentioned up thread solar is generally worth-while but especially with a battery it's not fit and forget. Using the battery on an agile tariff where you export power at peak times maybe your most effective payback and in this case a battery system that will play nicely with Octopus or whatever will be a deciding factor.

I presume you have a internet conection on site? is there good wi-fi or possibility of wired ethernet where the batteries and inverters are to be fitted?

[Jaded]

Hi,

Quick answer on the internet question - no, there isn’t internet. I’m not sure the other activity/tenant mentioned has it either.

[aidan.f]

Well that's a show stopper!. Assuming good mobile signal I do know that Giv Energy can supply a 4g dongle for their equipment.

I presume you have had site surveys before the quotes? If so I would be asking questions about competence.

[Jaded]

Cheers will ask the people doing the investigation! I don't know how the smart meter we are supposed to have does its comms.

[aidan.f]

Smart meters don't use 'home or business ' wi-fi but either a dedicated radio network (arqiva) or the mobile phone network..Assumptions that wireless comms 'just work' is a common problem. Maybe why your smart meter is useless.

[Jaded]

I'm not sure that the smart meter is useless, just that it is challenging to get useful data out of it.

[HTFB]

We have some scaffolding up at the moment for window replacement, so are looking at the economics of keeping some up and taking a hire extension fee as against a one-off scaffold to put the panels on. Also are getting structural survey advice (had recent roof surveys as we have a Circus School that wanted additional trapezes, so we had a survey and strengthening fitted)

Ah, I hadn't realised you were an excitingly non-standard property.

We had the roof surveyed and it cost us, um, quite a lot to triple up the trusses to take the weight of both panels and insulation. I might have been happier not to know.

[Jaded]

Yes, very excitingly non-standard!

Will await the structural survey information with interest trepidation

[Mrs Pingu]

Another thought occurred to me and that is the bottom line inverter seems quite oversized for your array (I assume it's 8kWh and not 8000) but still oversized. I have a feeling you need special permission from the DNO if you have a larger than normal inverter, even if your array is not that big. Some comments here https://freedomforever.com/solar-academy/solar-academy-lesson-5-solar-inverter-oversizing-vs-undersizing/
Again Gary on YouTube has some useful info on inverter sizing too.

Also, I'm not sure no internet is a total deal breaker. I've got a feeling our tradespeople unplugged our router last week as I've not been getting any data on the Solis app until today, but I've still been able to see my usage on the Octopus app. That doesn't help you track the exact usage and tells you nothing about the battery charging but it doesn't sound like a full no to me.

[Nutbeem]

Solis inverter and Puredrive battery seem a popular choice and combination and are what we have. They were what our supplier recommended and we are happy with them. I've no idea what make panels we have without digging into the paperwork.

Basic maths, a 9.5 kWh battery will store about £3 worth of electrickery assuming 35 p/kWh. So that's your maximum daily saving for simple energy demand shifting*. In winter time you maybe able to charge overnight at cheap rate and use daytime/evening. You should really know your peak time and base loads ( fridges freezers) which can/will be a significant battery drain.
*Octopus agile is a whole different game that I know little about but maybe better in your usage scenario - is the hall occupied every evening and will you use the energy?

This is what I'd initially thought, but having started out with just the panels then added a battery I don't think it's actually the case.

On a cloudy or overcast day our panel output may vary between 4kW when the suns out and 0.3Kw if it clouds over. If we're running major appliances at this time, washing machine or dishwasher, the battery will kick in as required to complement the panels.

I usually wait until mid-morning and our battery being at 40% before I put on the washing machine, then allow a few hours for the battery to charge again before I run the dishwasher after lunch, after which the battery should charge to 100% before sunset so that it meets our overnight power demand. Over the course of 24 hours I may get anything up to 8Kw of electricity out of our 5Kw battery. That does of course depend on being around in the day, which I am, and may not be quite so applicable to a Community Centre used mainly in the evenings.

Also not on Jaded's list, but worth considering, is a Solar Buddy for hot water heating. Provided the centre has an immersion heater I would suggest it's a no brainer. At a cost of about £250 it should easily meet your needs for hand washing and dish washing. Repayment time for our panel & battery system is 8 -10 years, but we haven't needed to use any grid electricity for water heating in the last 12 months so the Solar Buddy has already paid for itself.

[Quisling]

With respect to kit choice:

* select inverters based on longest warranty - many are 7 or 10 years now.
* panel output is just a measure of (a) panel size, (b) efficiency of conversion of photos to Watts.  Accordingly, selection of higher efficiency panels is important if you have limited roof space, or want to limit visual impact.  The more important criterion is the panel degradation - over time they will output less.  It's usually in the realms of <1% per annum (I've not checked recently, it could be much lower)
* ability to remotely monitor system performance via an inverter with an inbuilt webcard/SIM would be useful as it'll enable anyone interest to quickly spot if the system is not generating.  This could be because the inverter has tripped and needs a reboot, damage/vandalism to a panel, or something on the customer wiring side of the installation).

With regard to system sizing, and potential future boiler replacement, it's useful to be able to generate/store more power if you're ever planning to go down the heat pump route for decarbonisation purposes, though that probably doesn't impact on your purchase decision at this stage.

[Kim]

* ability to remotely monitor system performance via an inverter with an inbuilt webcard/SIM would be useful as it'll enable anyone interest to quickly spot if the system is not generating.  This could be because the inverter has tripped and needs a reboot, damage/vandalism to a panel, or something on the customer wiring side of the installation).

Not owning a house, I haven't paid much attention to this stuff, but it would seem highly desirable if the monitoring was reasonably standards based, and could be done locally (over some documented TCP/IP protocol or a serial interface or something) rather than relying on the manufacturer to provide and maintain some cloudy app stuff for decades.

As ever, the rule of thumb is that if some geeks on the internet have worked out how to talk to it with a Raspberry Pi or whatever, then you probably won't be entirely stuffed when the manufacturer succumbs to random acts of Finance a few years down the line.

[aidan.f]

Why I brought GivEnergy - Modbus over TCP/IP.  Home assistant plugin that just works. Their cloudy offering is hosted in the UK