Solar and battery system

rtho782

We're about to move, which we've been looking at for years, this will be our forever home which means I can finally do solar and battery!!

The house has a large, pretty south facing roof:
https://imgur.com/GEp93T8.png

And online calculators suggest I can fit a lot of panels:
https://imgur.com/sgzYu3a.png

Usage wise, we both drive EVs, we will be getting an Airconditioning multisplit for heating and cooling (we have this now) with the ambition of having gas disconnected.

I am a nerd, and have a server etc I run 24-7, this is probably 500W of base load.

I am thinking 2 EV chargers, that dump excess solar (but don't draw from grid unless overridden) into cars, then if the cars are full, house battery, then if that is full, hot water, then if that is hot, export. If export rates are high (assuming octopus flux) and battery full, export to grid from there.

Given that some of my loads are larger (EV chargers, ASHP), I think I probably want a large inverter. I'd like as much battery storage as possible. I have a maximum budget of ~£25k.

I was looking at the MyEnergi ecosystem (Zappi, Libbi, Harvi, etc), but it seems their closed system and no API won't integrate with octopus etc.

I was then looking at Givenergy, but there seem to be quite a few horror stories on here.

Are any of these systems actually good?

zxzxzx

Good plan imho. 

The geek potential is off the scale.

Car to home/grid chargers are on the horizon which would/could reduce your battery needs, and might be worth considering.

As you say it is the inverter that controls the amount of power available for real time use so go big on that.

Which company you choose is tricky, you will receive glowing endorsement when someone has no problems and the absolute reverse, that’s human nature.
I chose Givenergy on recommendation from a friend who had an interest in an installer and I have been completely happy to the point I recommended them to my brother, who has had an uptodate AIO of there’s installed and is also very happy.
More Info here, if you haven’t found it already. (Good & bad!)

https://community.givenergy.cloud/t/forums-meta

rtho782

I hadn't seem their forums, thanks!!

What worries me are posts like this one:

https://community.givenergy.cloud/d/3245-new-allinone-install-only-storing-12kwh-not-135kwh-specified/14

It also seems you can't have multiple all in one systems

zxzxzx

Understand your concern, the AIO is brand new (ish) and as a lot of tech subject to teething problems. I made that point to my brother and he thought the risk was outweighed by the benefits to him. YMMV!

Also their website says ‘ Connect up to 6 systems in parallel and achieve 80kWh of useable energy storage (coming soon)’ not sure if that suits? If it did you would then be an early adopter with all that entails. I am sure others will be along with alternatives.

Good luck with your decision!

Screwdriva

Octopus now supports Zappi, which is my go to EV charger for PV households.

If you include the smaller, lower roof, I see between 14-16 panels, which would be a 5.9-6.8kW sized system.  

For your perspective, a very similar quote I've seen this month:

16 X SHARP 420W Panels (30 year performance warranty)
16 X SolarEdge Optimizers
  1 X SolarEdge 6kW Inverter (20 year warranty) 
  1 X GivEnergy AIO (12 year warranty)
  1 X Zappi Charger 

~£15K installed with G99, bird netting and HIES. The AIO gets my vote as Octopus loves GivEnergy for some reason and the battery chemistry is sound. 

If you can wait, I'd recommend the SolarEdge V2H EV charger due this year, which may remove the need for a battery altogether. Another reason the geek in me loves SolarEdge If it was me, I'd go for the above system minus the battery and EV charger (saving £8K) and add those VAT free in the next 6-12 months. 

Netexporter

Also their website says ‘ Connect up to 6 systems in parallel and achieve 80kWh of useable energy storage (coming soon)’ not sure if that suits?

I think you need a 3-phase supply to do that. You will, eventually, be able to connect three A-i-Os to a gateway and you can have one gateway per phase. I imagine that it is regulatory approval, rather than actual capability, that is holding up multiple battery deployment.

Personally, I'd rather Givenergy would develop a bi-directional car charger, so you could just have one A-i-O and gateway, with the car for additional capacity.

amanda1024

Screwdriva said:

If it was me, I'd go for the above system minus the battery and EV charger (saving £8K) and add those VAT free in the next 6-12 months. 

Does this mean you don’t have to get a battery at the same time for it to be VAT free? I had been looking at getting a ‘battery-ready’ PV system, to reduce the upfront cost and see what my generation/usage ended up looking like in practice, but then I thought I’d seen that if you get the battery separately you have to pay VAT on it?

Netexporter

Batteries will be VAT free from February 1st, even if stand-alone.

Screwdriva

amanda1024 said:

Does this mean you don’t have to get a battery at the same time for it to be VAT free?

Correct. The government doesn't get much credit these days but they did just pass this new ruling. Batteries, diverters and Water Source Heat pumps will be VAT free going forward. 

Makes sense to install the above PV only system for £7K without the battery and then monitor and decide if its right for you in time, unless household consumption is significantly higher than the norm (>4000kWh p.a.)

We installed a PV only system 4 years ago as we import ~1600 kWh p.a., and instead of getting a battery, we added another 3.3 kW of panels last year. Haven't looked back since!

rtho782

Screwdriva said:

Octopus now supports Zappi, which is my go to EV charger for PV households.

If you include the smaller, lower roof, I see between 14-16 panels, which would be a 5.9-6.8kW sized system.  

For your perspective, a very similar quote I've seen this month:

16 X SHARP 420W Panels (30 year performance warranty)
16 X SolarEdge Optimizers
  1 X SolarEdge 6kW Inverter (20 year warranty) 
  1 X GivEnergy AIO (12 year warranty)
  1 X Zappi Charger 

~£15K installed with G99, bird netting and HIES. The AIO gets my vote as it Octopus loves GivEnergy for some reason and the chemistry is sound. 

If you can wait, I'd recommend the SolarEdge V2H EV charger due this year, which may remove the need for a battery altogether. Another reason the geek in me loves SolarEdge If it was me, I'd go for the above system minus the battery and EV charger (saving £8K) and add those VAT free in the next 6-12 months. 

This is interesting, thanks. I did have octopus themselves do a desktop quote (hopefully they don't sent too much junk mail to current owners!!) And they seemed to think fitting 20 panels on the main roof wasn't an issue, perhaps the size doesn't come across in the photo without scale, but if I measure on Google maps the apex of the roof is 13.4 meters west to east, so hoping for more than 6kW of panels?

I will need some sort of EV charging system day 1, but could potentially do something cheap I later replace. Neither EV supports V2L, is that not needed for this solar edge charger? The idea of ccs dc charging does seem faster and more efficient.

QrizB

rtho782 said:

... if I measure on Google maps the apex of the roof is 13.4 meters west to east, so hoping for more than 6kW of panels?

Above 3.68kW of export, you need DNO approval.

I know your earlier calcs suggest 35 400-watt panels for 14kWp of solar PV, but I suspect you'd need 10kW+ of export permission from your DNO to support an array that big (without clipping output hugely during the summer months). I'm not saying you won't get approval, just that it's quite a big ask.

Sure you can include it in your options - just double Screwdriva's £7k cost - but until your installer applies to your DNO, you won't know your limit.