Guidance for solar system please

Martyn1981

ddi said:

I think having the battery will be useful to import cheaper night time electricity to use during day. We are on octopus general rate atm. A couple of us regularly work from home so consume a lot of energy in the daytime.

Is there a maximum you can import overnight to a PW3 please? 

We have a combo boiler so I’m assuming an iiboost isn’t worthwhile? 

I’m thinking of installing an ev charger as hoping to get electric car at some stage. I e heard ppl talk of a ‘dumb’ charger but what is this?

huge thanks for all your suggestions. I’m very very new to all this! 

Being new to this is perfect timing. Folk on here can give loads of tips and advice for people before they jump in. Totally understand your high consumption, and it pretty much makes PV a no-brainer ..... so long as you get a decent quote now.

Only a thought, but perhaps you might want to consider two powerwalls? I'm not sure it's worthwhile, but perhaps worth a think at this stage, while you are working out the maths. For the better 6 months, I'd suspect one is enough, given you'll have a large PV system generating lots of spare. But maybe (only maybe) two might make sense for the poorer 6 months, given your high leccy consumption. I suspect the numbers won't quite work for 2, but just wanted to mention/suugest it.

Back to the heating. If you have a nice large area downstairs, then that's where an A2A unit might work well. You can use spare PV generation during the shoulder months (Spring and Autumn) to heat or help heat the house instead of GCH (gas central heating). And reduce gas consumption in the winter by 'pre-heating' the house on cheap rate leccy.

Just coming to the end of our first heating season using the two A2A units we have, and we never had to switch the combi on. So this year we can get it removed, once we've installed a hot water tank. We managed via running the A2A units hard overnight on cheap rate, then a bit more gently all day, using the cheap rate charged in the batts overnight.

Fingers crossed the Gov is going to include something positive about A2A units when they finally get round to the Spring overhaul of the warmer homes scheme. They now seem open to considering other technologies for support rather than just the £7,500 subsidy for ASHP's heating via a wet (radiator) system.


Regarding the EV, I've not heard of a dumb charger, but I suspect it means the standard charger that typically comes with the EV, commonly known as a 'granny charger' as it's slower. A 'granny' supplies about 2.2kW, and can be plugged into a socket*, whereas a 'smart charger' supplies 7kW and needs to be professionally installed, and will cost around £1k. If you're on a cheap rate, then a smart charger will allow you to pump a lot more into the car during the cheap rate period.

*Technically any socket will do, but drawing 2kW for many hours could put a strain on some, so worth considering the ring it's on, or utilising a separate ring/socket. Also, you can get granny cables where the power can be selected, so instead of 10A/2.2kW(ish) you can dial down to 8A, 6A, 5A or so, and charge away all day and night, when the vehicles parked at home.

Solarchaser

A few friends have gotten solar in the last couple of years and managed to stick to the £1/kw on solar only deals, but it seems to be the case that because batteries are still somewhat unknown, installers think they can charge what they like for them.

I'd advise getting a quote with solar only. 
You are a high electric user, almost as high as I am, though mine is heating also, and with the amount you consume, you will struggle to get a battery system that will cover your usage,  without paying huge sums, as I'd assume in the winter months you are pretty close to 60kwh / day, that's essentially more than 4 powerwalls or £28k

If you are willing to get your hands metaphorically dirty, then you can massively reduce the price per kwh of battery storage, by buying DIY kits and assembling yourself.

Tesla powerwall is a good enough bit of kit, but is very expensive per kwh of storage, £7k for 13.5kwh is pretty awful these days, when you can get self build kits for £1500 for 15kwh, so 4 of them would be £6k

There are a few batteries that can go outside, not just tesla, but more broadly, if you considered buying a small plastic / wooden/ concrete prefab hut to store batteries in, you wouldn't need them to be waterproof. 

Solar diverters for hot water are pretty much obsolete these days, because of export tarrifs.
If you solar divert 1 kwh to how water instead of exporting that kwh you are losing around 6-9.5p/kwh
Because you can buy electricity off peak for 6.5-8p/kwh, and you can sell electricity at up to 16.5p/kwh.

Same is true for solar ev chargers like the zappi, you can put 1kwh of solar into your car, or charge the car off peak and export that kwh of solar.
Dumb chargers are ones like the rolec charger and others where you plug the car in at whatever time of day and it just starts charging, no logic involved, whereas smart chargers will have at the minimum a timer to start charging when you are in the off peak period.

I have a Zappi, and I have an Eddi, and 2 years ago I used them to scavenge as much solar as I could for my hot water tanks and EV and batteries, then I moved to an Export tarrif and instead do all my heating and charging (both) overnight, and export all my solar.

If you are using 14,000kwh of electricity a year, you are probably paying between £3-4000 and year on electricity. 

I'm using a bit more, and this year, my electricity bill should start with a minus.

Mine has been a journey over 10 years long, and as Martyn1981 said, you are in a good position to be starting now, as you can learn from all of our collective mistakes and choices

Screwdriva

Not very often I disagree with experienced members like @Solarchaser but this is definitely one of them.

Solarchaser said:

There are a few batteries that can go outside, not just tesla, but more broadly, if you considered buying a small plastic / wooden/ concrete prefab hut to store batteries in, you wouldn't need them to be waterproof. 

Battery forums are littered with posts about woeful winter performance and discharging issues. This applies to higher end brands like SolarEdge and GivEnergy's All in One, which surprised me! It is widely acknowledged that Tesla's thermal management is best in class. Aesthetically speaking, they look great without any DIY waterproofing! 

Solarchaser said:

I'd advise getting a quote with solar only. 
You are a high electric user, almost as high as I am, though mine is heating also, and with the amount you consume, you will struggle to get a battery system that will cover your usage,  without paying huge sums, as I'd assume in the winter months you are pretty close to 60kwh / day, that's essentially more than 4 powerwalls or £28k

I can't comment specifically on OPs usage/ generation patterns but given they are high daytime users, a battery may provide enough capacity to get them to bridge to nighttime charging tariff windows. There are other benefits such as whole house backup and storm watch for outages as well as access to the Intelligent tariffs for the generation months - these should be considered when selecting a battery. If more storage is needed, PW3 13.5kW expansion powerpacks cost < £6K installed to the original PW3. 

Agreed that they're nowhere as cheap as Fogstar/ Seplos kits but not everyone is a DIY/ fix it yourself type of user. 

Solarchaser

Screwdriva said:

Not very often I disagree with experienced members like @Solarchaser but this is definitely one of them.

Solarchaser said:

There are a few batteries that can go outside, not just tesla, but more broadly, if you considered buying a small plastic / wooden/ concrete prefab hut to store batteries in, you wouldn't need them to be waterproof. 

Battery forums are littered with posts about woeful winter performance and discharging issues. This applies to higher end brands like SolarEdge and GivEnergy's All in One, which surprised me! It is widely acknowledged that Tesla's thermal management is best in class. Aesthetically speaking, they look great without any DIY waterproofing! 

Solarchaser said:

I'd advise getting a quote with solar only. 
You are a high electric user, almost as high as I am, though mine is heating also, and with the amount you consume, you will struggle to get a battery system that will cover your usage,  without paying huge sums, as I'd assume in the winter months you are pretty close to 60kwh / day, that's essentially more than 4 powerwalls or £28k

I can't comment specifically on OPs usage/ generation patterns but given they are high daytime users, a battery may provide enough capacity to get them to bridge to nighttime charging tariff windows. There are other benefits such as whole house backup and storm watch for outages as well as access to the Intelligent tariffs for the generation months - these should be considered when selecting a battery. If more storage is needed, PW3 13.5kW expansion powerpacks cost < £6K installed to the original PW3. 

Agreed that they're nowhere as cheap as Fogstar/ Seplos kits but not everyone is a DIY/ fix it yourself type of user. 

Disagreement is not a bad thing, we all found our way to what we are happy with, through different paths.

However, you realise I'm sure that I have fogstar batteries, and they are in a cold loft, as in its minus in the loft when it's minus outside, and my batteries were flawless right through the winter.
People tend to notice performance issues when they are running close to the batteries limits and so need their full available charge and discharge rates.
The fogstar modules are 100a modules, running 2 means they are good for 200a of charge and discharge, but most of us run them at 70a max, so needing only 1/3rd of full charge and discharge.

I based my advice on things I've done and can stand beside, or I'll state i haven't done it myself.

And while I actually agree that most of the OP's summer use will be covered by solar, that probably only makes up around 4000kwh of their 14000kwh annual consumption, and so it will be heavier in winter at which point solar contribution will be negligible,  hence why I'd advise a much larger battery.

NedS

Solarchaser said:

I'd advise getting a quote with solar only. 
You are a high electric user, almost as high as I am, though mine is heating also, and with the amount you consume, you will struggle to get a battery system that will cover your usage,  without paying huge sums, as I'd assume in the winter months you are pretty close to 60kwh / day, that's essentially more than 4 powerwalls or £28k

For high users, particularly those with heat pumps, a tariff like Octopus Cosy can work well in winter where there are 3 cheap slots spread across the day totalling 8h, so 3 opportunities to recharge batteries. A 13.5kW Tesla PW3 combined with a little load shifting could realistically cope with 50-60kWh per day load keeping import totally at the cheap rate. But I agree, trying to import/charge on a cheap overnight tariff and provide sufficient battery to last the day is going to be cost prohibitive.

ddi

Ooh it’s getting complicated. 

There’s no way on this planet I can do a DIY set up but I’d be happy with batteries in the loft @Solarchaser as it’d obviously be great to use as little from the grid as possible. I’m not expecting to export any energy. Should I discuss with the potential installers a higher battery capacity that can go into the loft? 

ddi

@NedS are the 3 times a day the same set times each day with cosy? 

QrizB

ddi said:

Ooh it’s getting complicated.

Not really, it's only complicated if you want it to be.

Id suggest that you get the PV fitted on the roof, that's the uncontroversial bit.You can think about a battery afterwards.

(It's your decision in the end, we can only offer suggestions.)

NedS

ddi said:

@NedS are the 3 times a day the same set times each day with cosy? 

Yes, but Octopus Cosy is a heat pump tariff, so you need a heat pump. I has assumed you may have electric heating given your very high usage, but apparently not.

https://octopus.energy/smart/cosy-octopus/

Solarchaser

ddi said:

Ooh it’s getting complicated. 

There’s no way on this planet I can do a DIY set up but I’d be happy with batteries in the loft @Solarchaser as it’d obviously be great to use as little from the grid as possible. I’m not expecting to export any energy. Should I discuss with the potential installers a higher battery capacity that can go into the loft? 

I'd see it as multiple options or opinions rather than complications to be honest.

Most well weathered members of this part of the forum would advise solar always, as long as you are not paying through the nose for it, and get as big as you possibly can, fill the roof if possible.

After that, people's own experiences colour their advice.
For instance, Screwdriva does alot of helping people with solar quotes, and pushes historically for certain makes of panel and solaredge inverters as he has had good experiences,  or his research supports it, more recently he has pushed for Tesla, as his research supports it.
He also always pushes for 10 year warranties, all very honourable and should be applauded!

I've never used solaredge, and the friends that I have who got a system with solaredge, didn't need it, and essentially paid extra for something that wasn't required as they had no shading issues.
There is an argument about individual panels failing, but that is so very rare as to make the point moot.

I currently drive a Tesla, and encounter fairly frequent limitations and glitches in its software/hardware, as well as various changes to the assumed contract you think you have with tesla, and am especially disappointed in it's battery health management, so I'd never willingly buy anything Tesla, as in my opinion their bombastic "we are great at this" approach is never actually realised.
Don't get me wrong, the car is an good drive, but the reputation doesn't hold against reality, despite what online searches tell you.

I will only recommend things I've had actual physical experience of, and the same for recommending against.
I'd recommend against growatt as I had very bad experiences with them, which only ended when I threatened them with court.

I'd recommend against paying extra for a 10 year warranty, as I did, and the 8 year old (at that time) company who installed my first solar array passed the sniff test, so I thought i was doing good, until my inverter failed at year 6 and I was told the company had went under 2 years previously and the bit of paper saying it was guaranteed by mcs was worth nothing, as it wasn't.
That by no means says every companies 10 year warranty is the same, I just won't push it as I've been burned.

I'm probably what would be called an avid DIY'er, as are a few on here, I suspect QrizB is the same, and so when my inverter failed and I found the warranty was invalid, I took the inverter apart and found a couple of clearly burned out relays, i know how to solder and so i replaced them. It was easy enough, and was a common fault on that type of inverter, so i picked up another two with the same fault super cheap from ebay and they run my other arrays.
I wouldn't say I find it easy, id more say the challenge makes it more interesting,  and makes me wonder if i could.

However, of course I accept not everyone is the same, and so I understand the prospect of DIY'ing a battery storage system is beyond the limit of what most people would attempt, but I'd also say, think about it, dip a toe in, play with the idea of "what if".

What if you got pure solar quotes and got them to include a hybrid inverter, but no batteries. 

What if you could buy brackets online to take a couple of hundred kilos on a shelf, and secure them to your loft wall, as you don't want all that weight on your joists.
(Someone will be along to say current advice is not to put them in the loft)

What if you were able to get 150A DC wires a couple of meters long from ebay, amazon etc

What if you could get a 150A isolator from ebay etc

What if you looked at you tube videos of how to put crimps on the end of wires

What if you could get batteries that came pre assembled and could talk to your inverter 

What if you could save £500 per battery by following a you tube videos about assembling one, and give it a go, knowing hundreds of people have done it already.

It all starts, FOR ME, with what if, and you found your way here, by asking yourself if your quotes were good, or your thoughts were right.
You asked yourself, what if... I ask people online