Ronski's Solar & battery DIY build with whole house backup

[Ron-ski]

We already have 4kw of solar on our house roof, which was installed in December 2015, this is comprised of 16 panels witha Solaredge inverter and optimisers, and uses the best two roof's of the house.

As some of you might be aware on the solar thread I've been looking into getting an additional array installed on our detached flat roofed double garage, it will be 12 405w panels in an east west arrangement, the panel angle will be quite low at 10 degrees, this is to keep below planning requirements, anything over 200mm above the highest part of the rood and you require planning permission.

The mounting brackets for the panels are custom designed, and will be made by myself using 50 x 50 x 3mm angle. I still need to get up on the roof, and measure the pitch and allow for that in the design.

I will also be making a custom battery rack of my own design, it will have four pull out draws, each draw can hold 16 cells, and using 16 280ah cells makes 13.44kWh to 14.56kWh battery

As this is a garage install I need to run a new sub main from the existing incoming supply to the garage, then a new sub main back to the existing, this will be using 25mm SWA, and will mean the whole house will run off the inverter in the event of a power cut.

Close up of the battery with busbars

Oh, and yes I do have an electrician for the 240v AC work.

 

[Ron-ski]

@BUDFORCE Thanks, think I'm going to need it.

@Rroff They are EVE 3.2v 280ah LifePO4 cell's.

 

[Ron-ski]

Shame they are about 4x more expensive than gel lead-acid batteries, there seems to be so many advantages to LifePO4.

They can be had for a lot cheaper than I paid from China, but you take your chances on what you get. They could be secondhand, a couple of year's old, or you don't get any cells at all, seems a bit of a lottery.

I’m excited to see how this progresses. If you have a TNC-S electricity supply then beware the rules of earthing as they relate to outbuilding including garages. I mention since your house will effectively become a sub main of your garage.

I understand there are some issues with earthing as it's a whole house backup, but that's the electrician domain, but I would like to understand it more. I know the DNOs earth cannot be relied on in the event of a power outage so a local earth is required, which probably means converting the house over to an earth rod.

any chance of putting up details of what parts you've ordered and from whom? Thinking of something similar myself and keen to find out what other people are buying, especially around cells, bms, etc.

I'll post up a list of what I've ordered later.

@deuse They are the ones with the double bolt hole per terminal. Yes, just check they are the K series. That was a good price, who did you use?

 

[Ron-ski]

I had initially planned on using a Multiplus II 48/5000, then ended up deciding to go large and use Multiplus II 48/10000 until someone on the main solar thread pointed out it's not G99 approved, which is a bummer as it has built in anti islanding, where as the Quattro 48/10000 doesn't.

Having emailed Victron this morning asking when it will have G99 approval I've just had a very quick reply from them.

The Multiplus II 48/10000 will be approved at some point but we don’t have a timescale for this, unfortunately

So I have two realistic options, use the Quattro and fit an external anti islanding relay, or use two Multiplus II 48/5000 in parallel. Space wise the Quattro would be better, cost wise the two Multiplus II might be better, also this would give some redundancy.

 

[Ron-ski]

Push for a good deal. And do it through email and not the site

Thanks for the info, I may do this for a second set, I suppose the K series hasn't been around long enough to end up with old batteries?

 

[Ron-ski]

The cheapest I've found so far is a French ebay store. Multiplus II 48/5000 £1223, Quattro 48/10000 £2891

MultiPlus-II 48/5000/70-50 Victron Energy – PMP482505010 | eBay

Find many great new & used options and get the best deals for MultiPlus-II 48/5000/70-50 Victron Energy – PMP482505010 at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

Victron Energy Quattro Convertissuer Chargeur 48/10000/140-100/100 -QUA481030010 | eBay

Find many great new & used options and get the best deals for Victron Energy Quattro Convertissuer Chargeur 48/10000/140-100/100 -QUA481030010 at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

I do need to check Victron will honer the warranty, but I've heard they will.

 

[Ron-ski]

It's never very clear, but I thought eBay automatically took that in to account and added it on?

 

[Ron-ski]

Just found it, the last line is the catch - that's a pain!

Hopefully my electrician can come up with some good prices.

Goods shipped to the UK from abroad​

Effective 1 January 2021, eBay is required to collect VAT on certain orders delivered to UK addresses:

• Orders up to £135 sent from outside the UK
• Orders of any value where the item is located in the UK, but the seller is not a UK seller

For higher value items, VAT and duties are also likely to apply. However, VAT on purchases valued at over £135 will be payable directly to the UK customs authorities by the buyer.

 

[Ron-ski]

Yes, that's the plan, and I have a spare PI - seen the video on Andy's off grid garage, I don't think the GX device or the built in one adds anything extra over running Venus OS on a PI does it?

 

[Ron-ski]

@Journey Nice one, was just about to Google to see what I can find, thanks. Unfortunately can't purchase the inverter(s) until I've talked to the electrician and decided which way we're going.

 

[Ron-ski]

I can make room in the garage for two Multiplu II 48/5000s, especially at a saving of £575 and no external anti islanding, although there will no doubt be extra electrical work.

Are you going whole house back up?

 

[Ron-ski]

How are you doing your anti islanding?

 

[Ron-ski]

This is an interesting snippet if you have another AC connected PV array like me.

AC-coupling and the Factor 1.0 rule [Victron Energy]

www.victronenergy.com

 

[Ron-ski]

As far as I can tell the Quattro doesn't have anti-islanding and it therefore needs an external system

Do I need an Anti-Islanding box for my ESS? (Sweden) - VictronEnergy

community.victronenergy.com

2. System design

www.victronenergy.com

When is anti islanding device NOT required? - VictronEnergy

community.victronenergy.com

 

[Ron-ski]

Ah, missed your link earlier, it certainly does state it is acceptable - thanks.

Question now is which is better, single Quattro 10000 or two Multiplus II 5000's?

 

[Ron-ski]

50a would be ok at the moment, but probably not in the future, I'll see if I can get an answer.

 

[Ron-ski]

My cells are scheduled for delivery tomorrow, the tester etc won't be here until early September, but that's not far off.

 

[Ron-ski]

Items ordered so far:

• 16 EVE LF280K - arriving tomorrow apparently
• JK BMS B2A20S20P-CAN
• 2.5" touchscreen for BMS
• Digital YR1035 Lithium Battery Internal Resistance/Impedance Tester
• EBC-A40L High Current Lithium Power Battery Capacity Tester

Items currently got.

• 43 meters of 25mm 3 core SWA
• Wylex 100amp fused switch DSF100M

The last two items on the first list is purely for testing the cells.

I've taken a Victron drawing and modified it to show what I'm aiming to achieve. The bypass switch is just a means to bypass the inverter, if it stops working the whole house loses power, so I need an easy way to bypass it.

 

[Ron-ski]

Cells have arrived, couldn't get my phone to scan the code, but once I worked out I needed to enter both numbers together manual entry worked.

Eve LF280K
Date: 2/6/2022
City: Jingmen

There's various other info as well.

No idea if the date is June or February.

Packaging has been updated for the new terminals.

 

[Ron-ski]

I've checked 7 of the cells in total, and they are all 6th of Feb 2022. I'll check and log all of them tomorrow.

How are you going to load manage your home PV vs your garage PV and battery?
The system in your house will presumably see the supply from the garage as if it were the grid, whereas the system in the garage will just see reduced load on the supply side when house PV is producing, but what happens when house PV production is greater than house load? Ideally in that scenario your garage batteries would charge from AC.

When the house PV production is greater than the house load the Victron inverter will use the excess to charge the batteries, once the batteries are full the excess will be exported.

Another scenario we need to consider is in the event of a grid failure, the suns shining brightly, theres low house load and the batteries being fully charged. The house PV will keep producing power as it still see's grid voltage from the Victron, in this the scenario the Victron inverter can alter the frequency, once it hits 52.5Hz the Soleredge inverter will turn off, well this is what I've been told, so hopefully that's how it will work. Newer Soleredge inverters can actually regulate their output as the frequency rises, whereas the older ones are either on, or off.