Simplest AC Coupled System

[Benguela]

Hi All,

 

Got a SolarEdge based PV system (5000 HD Wave Inverter) this summer. Works a treat but can only be DC coupled with LG Chem or SolarEdge high voltage batteries. 

 

I'm a bit fed up spending money after going the 'premium' route with the SolarEdge stuff (and I'm not quite sure it was the right choice).

 

So I'm wondering: What is the cheapest, simplest to fit AC coupled battery solution that I could scrounge from the ads on Facebook Marketplace? I see various Victron, Solis and Solax inverters on there for £300-£400 upwards. And I see Pylontech batteries for about £600 upwards. So surely it's feasible to: 

 

- start by getting the right inverter

- wait for a good price on a Pylontech battery that someone is throwing out

- get the whole system up and running

- let it run for a season to see how it works

- buy more Pylontech batteries if I like the setup and can find one at a good price.

 

To show the depth of my ignorance, I'll admit that I basically don't know what inverter I need. Am I looking for an inverter/charger? Or an inverter and a separate charge controller? It looks like they're sometimes packaged in the same device and sometimes separate. 

 

And how would I end up controlling the whole setup? Presumably, an aftermarket AC coupled system isn't going to talk to my SolarEdge inverter, so I will need to tell the AC coupled battery system when to charge and when to supply. Any useful hints and tips about integration?

 

I know very little, as you can see, so I'll get my friendly electrician to fit it at a day rate. But the whole thing must still be simple and foolproof enough that he doesn't puzzle over it, take days, go to Screwfix for some parts and then tell me that I bought all the wrong stuff.

 

As it'll be fairly small scale, hopefully it won't affect the G98 that I've already got in place?

 

[Dillsue]

3 hours ago, Benguela said:

Got a SolarEdge based PV system (5000 HD Wave Inverter) this summer.

As it'll be fairly small scale, hopefully it won't affect the G98 that I've already got in place?

 

Hopefully thats a typo and its a G99 approval that you already have in place for your 5kw inverter as G98 only covers you up to 3.68kw. Adding AC coupled batteries will be potential extra export on top of what you already have so a G99 application would be needed unfortunately.

 

Its a shame SE dont do smaller/cheaper or scaleable battery options as a DC coupled system seems to have so many advantages. 

[Benguela]

Yes, just a typo, we've got a G99, all above board and legal.

 

 

[Thorfun]

I've gone LuxPower (SquirrelPod) and Chinese batteries (Hanchu Ess https://www.hanchuess.com/low-battery.html). it's a good system that seems to work well but I've since learned it only supports 13A on EPS/UPS load so not quite a whole-house power cut solution but definitely enough to keep the lights and the router on!

 

the LuxPower inverter works by using CT clamps on the solar and grid feeds and it works out if it needs to discharge or can charge. seems to do a great job so far but it's only been running a couple of weeks and we're not even in the house yet! but I do have the EV charger running off the new house so I can set that to get energy from PV and to supplement it from the batteries if PV isn't generating enough.

 

I bought all my stuff direct from Big Green Beard and my electrician wired it up after I hung it on the wall. this is from before it was wired up.

 

[Thorfun]

ps. as @Dillsue said, if you're getting an AC coupled battery system then you'll need a new G99 application. 

[Benguela]

3 hours ago, Thorfun said:

I've gone LuxPower (SquirrelPod) and Chinese batteries (Hanchu Ess https://www.hanchuess.com/low-battery.html).

Looks good!

 

 

[pudding]

I had a pre-existing 4kWp array from 7years ago, and this year have added another 3.6kW Sunsynk hybrid inverter with 3.5kW more PV panels and 4x Pylontech US3000C batteries giving me 14kWh storage. The inverter uses a single CT clamp around the incoming mains grid supply, so that whenever export is detected, it will redirect and charge the batteries if needed, so it scoops up excess from the pre-existing array too; it doesnt care where the excess comes from. 

[Solarexploits]

Just a thought, would it not be cheaper to buy an off grid inverter & simply take part of the house off grid as a completely separate setup? This is what I've done using SH panels & batteries with a new inverter

 

So far as I have been able to establish providing the circuits you take off grid are completely separate to your existing consumer unit etc. then there is no further application required, as, although generating, the generating side is not connected to the grid?