Solar panels and battery - any real world reccomendations?

[Balwant]

EVI Group in Dunfermline - as I said above, really nice bunch of guys, very straight and no nonsense. Have done everything they said they'd do absolutely spot on the time.

Very similar set up to yours but I’ve gone for Dual 3.6kw inverters for the purpose of a higher AC output rate to meet our peak draw which at times can be 6-7kw as we cook with electric. In addition as there will be 1 battery on each inverter, the charge rate will be maximised for Solar and if charging from the grid during an off peak period

Overall my system when it finally gets installed will be

20 x 395w Panels
X2.Givenergy 3.6kw Gen2 Hybrid inverters
Each with a Givenergy 9.5kwh battery
Myenergi Eddi
Also decided to go with Tigo optimisers on every panel not just for the shading but to allow panel level monitoring too via the cloud.
Bird protection to keep those pesky Pigeons away.

 

[katie279]

Hmm, I do wonder if I should get another inverter..... we too have pretty high peak draw (electric cars, electric cooking etc). Might ask the guys today.

I didn't go with panel optimisers, but it's a totally clear roof, so hopefully that won't be a problem either.

 

[katie279]

Is there a way to split these inverters across three batteries? Given our use 3 x 9.5 batteries would be perfect, but our peak draw would suit 2 X 5kw inverters, would I have to have two batteries attached to one inverter or could I combine?

 

[Balwant]

Is there a way to split these inverters across three batteries? Given our use 3 x 9.5 batteries would be perfect, but our peak draw would suit 2 X 5kw inverters, would I have to have two batteries attached to one inverter or could I combine?

Batteries have to be physically connected to an inverter so would need to be on dedicated inverters. 2/1

 

[Mercenary Keyboard Warrior]

Ah battery limitation, worth checking with them how they work when more than 1

Mine (solax triple power) the charge and discharge rates go up as you add upto 3 slaves (they use a master and slave system), maybe Givenergy operates the same but not obvious from their literature

 

[katie279]

Hmm that's interesting then - ok, have emailed our fitters

Agree it's pretty opaque - this set up appears to suggest a master/slave set up also:

GivEnergy - New 9.5kWh Battery installed

The new GivEnergy 9.5kWh battery has been installed. I give you a quick overview of the components in my system, and talk a little about 'CableGate'.Octopus ...

www.youtube.com

But struggling to find if discharge is affected by pairing more (not entirely sure how this would work to be honest, would have thought it'd be the inverter that would govern that?)

 

[Balwant]

Ah battery limitation, worth checking with them how they work when more than 1

Mine (solax triple power) the charge and discharge rates go up as you add upto 3 slaves (they use a master and slave system), maybe Givenergy operates the same but not obvious from their literature

You can also daisy chain the Givenergy batteries in a master/slave config.

 

[Mercenary Keyboard Warrior]

You can also daisy chain the Givenergy batteries in a master/slave config.

Thats what I expected so I would be very surprised if the charge/discharge rates didnt go up in that scenario

 

[Balwant]

Thats what I expected so I would be very surprised if the charge/discharge rates didnt go up in that scenario

Charge/Discharge would be limited to the inverter capacity so would still be 3.6kw for the Givenergy GEN2

 

[Mercenary Keyboard Warrior]

Charge/Discharge would be limited to the inverter capacity so would still be 3.6kw for the Givenergy GEN2

Is that for battery only since it makes no sense to have a kw inverter that does 3.6 when they make a 3.6

Edit : Although the spec sheet does seem to list that, quite odd IMO

 

[Balwant]

Is that for battery only since it makes no sense to have a kw inverter that does 3.6 when they make a 3.6

Edit : Although the spec sheet does seem to list that, quite odd A

 

[Balwant]

As far as I know the 3.6kw is the discharge limit to AC. The inverter can still do a combination of supplying the house with AC and charging the battery with DC above the 3.6kw limit. With the 3.6kw Hybrid I believe it’s around 4.7kw. So you could supply 3.6kw to the house and the remainder into the battery. With the 5kw inverter I believe the total limit is 6.5kw but again limited to 3.6kw AC. Hope that makes sense but happy to be corrected.

 

[Journey]

Thinking on this some more, could you explain why you don't think this'd be worth the expense?

At a simple level I'm thinking it'd give me an extra 14kwh per day through the winter @ 7.5p/kw, rather than 60p+ p/kw which is where things are going (let alone April peak!).

Given we use around 14,000 kw per year, this would surely pay for itself in a few years? (I'm thinking another inverter and a third battery to take us to 28.5 kWh of storage?

Am I missing something?

I suppose given your very high average usage it might be worth it with the 3rd battery, but I was only taking into account the second inverter and the two current batteries.

14kWh per year is around 269 per week (average), so three batteries full cycled would give you 200kWh of that almost. What happens when the solar starts working well in the spring time and the sun starts rising earlies and setting later, are you going to set the DoD to a lower amount to increase the life span of the batteries?

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On another topic Katie, GivEnergy has an open API for the battery and inverter, with the services all hosted on AWS. The battery/ies can be controlled locally via GivTCP or public API’s, some of it pretty well covered and documented.

 

[katie279]

Great thoughts as always Journey.

I also need to add in that I can get it for 0 VAT now as part of the deal + I don't know where 13-18% inflation + enormous demand will take us in 6-12 months.....! It feels like Solar gear is fast becoming the new graphics cards....

I don't know how effective the solar will be (I have estimates obviously), but given I've got a Tesla model Y on order (which will take us to two EVs) and plan to replace oil boiler with high temp heat pump, I'm struggling to see how I'd get to 'too much' energy....!

 

[HungryHippos]

It feels like Solar gear is fast becoming the new graphics cards....

Very possibly the case, those of us getting installs this year may look like geniuses very soon!

 

[DampCat]

God I hope the lead times aren't insane

 

[HungryHippos]

God I hope the lead times aren't insane

Install costs are likely to be higher as people can pick and choose their quotes, installers seem busy so demand is up, and kit prices are up as well.

 

[gpuerrilla]

It certainly tipped the scale, I was wanting solar for a while then these hikes cemented it. My only regret is not actioning it sooner so I captured the glorious April weather, by the time I had ordered the stampede/demand was kicking in and had a couple of week pushback due to parts.

 

[DampCat]

I don't mind the money so much. I couldn't deal with it earlier in the year and was half hoping it would be quieter moving into autumn/winter when effectiveness drops.

Same with the AC survey I have booked in.

I just want it sorted before it turns into "trying to buy a bike in the pandemic".

 

[HungryHippos]

I've missed the whole of summer basically but 3 month DNO and some delays will do that, at least it will be kicking in hopefully as of early next week, and I can test the system works.

Main thing for me was getting it installed before the October price rises kicked in.