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Discussion Starter · #1 ·
Hey everyone

New to the forums. I'm just about to get a solar array system and home battery system installed with idea for ev charging in near future.

I've had lots of quotes but some have hybrid inverter (givenergy, growatt) and others have ac coupled.

I'm trying to decide which is the right to go for and one that will works best for ev charging and also solar generation.

Would anyone be able to share their advice and experience? That would be very much appreciated.
 

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Like everything, there are pros and cons.

I’m just about to install an AC coupled inverter for two reasons: I already have a solar inverter so the AC coupled is cheaper than a hybrid and I have a FIT generation meter so it’s easier to keep away from that, plus a hybrid would record less generation because the losses in battery storage would be before the meter.

Obviously your situation doesn’t have either of those constraints. Advantages of hybrid are (slight?) improvement in efficiency and higher output power, although how often that is genuinely useful is debatable, plus presumably a lower cost/space of one inverter rather than 2.
 

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I have a hybrid system with Luxpowertek inverter, put together by the installer.
I don't think it makes a huge amount of difference, as the choice may depend on the size of your panels and storage and the available converter capacities. I think they will all basically do the same things.
 

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I have a hybrid system with Luxpowertek inverter, put together by the installer.
I don't think it makes a huge amount of difference, as the choice may depend on the size of your panels and storage and the available converter capacities. I think they will all basically do the same things.
I've got a system with each panel have a micro inverter. sorry no choice, it has to be ac coupled
In any case, I do not like the idea of running high voltage DC cables between roofspsce and basement
 

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Have a look at recent videos by The EV Puzzle on YouTube who has just had a new Huawei battery installed and the Solis inverter replaced by a hybrid.
 

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I have a Huawei inverter and LG battery installed.

Bear in mind if you have a direct DC connection you will be power limited to that of the inverter.

If you have an AC couples system, the PV and battery can work together to give you higher peak output, should you need it.
 

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I have the Givenergy 3.6kW hybrid with DC coupled 8.2kWh battery and Zappi charger. With the Zappi you can set the "Export Margin" config so that it will only direct power to the EV when the home battery is at 100% and therefore any excess solar is going to the grid.

For monitoring purposes, AC coupled is better, but there's ways and means to manage where the power goes.
 

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Discussion Starter · #8 ·
I have a Huawei inverter and LG battery installed.

Bear in mind if you have a direct DC connection you will be power limited to that of the inverter.

If you have an AC couples system, the PV and battery can work together to give you higher peak output, should you need it.
Is it possible to overrate hybrid inverter to get around this issue? Eg 5kw instead of the 3.6?

Are there more issues with AC coupled with the Dno application?

I have the Givenergy 3.6kW hybrid with DC coupled 8.2kWh battery and Zappi charger. With the Zappi you can set the "Export Margin" config so that it will only direct power to the EV when the home battery is at 100% and therefore any excess solar is going to the grid.

For monitoring purposes, AC coupled is better, but there's ways and means to manage where the power goes.
This is pretty much the setup I want but thinking of going for the 5kw hybrid inverter instead so I'm not limited but I'm not sure if that has any implications on the Dno application? I'm thinking it shouldn't as the excess power will be diverted into battery or ev at later date and any excess will still be only 3.68 if exported. Is my thinking correct there? Is there any benefit in going bigger on the Inverter?
 

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Is it possible to overrate hybrid inverter to get around this issue? Eg 5kw instead of the 3.6?
If you mean get an inverter that is rated at 5 kW or 6 kW, then yes. The price isn’t much more and I’d recommend doing this as it will allow you to add panels at a later date if you want to.

The maximum rated single phase inverter you can buy today is 6 kw, which is what I have.
 

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Is it possible to overrate hybrid inverter to get around this issue? Eg 5kw instead of the 3.6?

Are there more issues with AC coupled with the Dno application?



This is pretty much the setup I want but thinking of going for the 5kw hybrid inverter instead so I'm not limited but I'm not sure if that has any implications on the Dno application? I'm thinking it shouldn't as the excess power will be diverted into battery or ev at later date and any excess will still be only 3.68 if exported. Is my thinking correct there? Is there any benefit in going bigger on the Inverter?
The only difference I heard was that you have to just notify the DNO for systems up to 3.68kW, but for greater than that you have to get permission from the DNO.

How many kW of panels are you having installed?
 

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Discussion Starter · #11 ·
The only difference I heard was that you have to just notify the DNO for systems up to 3.68kW, but for greater than that you have to get permission from the DNO.

How many kW of panels are you having installed?
Depending which quote I go for either 4.69kw or 4.56 or 5.74. The 5.74 is with growatt hybrid and growatt 6.5kwh battery, the 4.69 is with giv energy hybrid and 8.2kwh battery and 4.56 is 5kw Solaredge inverter and givenergy 8.2kwh battery. All quotes are around same price. My gut feeling is to go with the bigger array but that has smaller battery so the 4.69 feels like best compromise.
 

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Are there more issues with AC coupled with the Dno application?
Shouldn’t be. The DNO is only interested in the max capacity of the Power Generating Facility, which is the sum of the capacities of the Power Generating Modules. With an AC, you’ll end up putting 2 PGMs on the form, the PV inverter and the battery inverter. With a hybrid it will just be the one.

The application form has provision to record an AC storage inverter as an addition to a solar PV if the latter has previously been registered.
 

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Discussion Starter · #13 ·
Just had a quick look at two days worth data from 1800-0900, one in march and one in June. Used roughly 4kwh in that time so basically half of the 8.2kwh battery I'm thinking of getting. I think that tells me that the 8.2 is the right one to go for. I know it's only two days and probably should look at more which I will but our usage hasn't changed much between march and now.

Also was thinking that battery dependency will be more in winter due to less solar so this number will effectively be higher.
 

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Yeah I'm glad I went for the 8.2kWh. At the moment, I set the battery to charge to 40% overnight on Octopus Go 5p rate and that covers breakfast kettle & toaster etc until the sun comes up and tops it up to about 100% by midday.

In winter I'll probably charge it to 100% overnight as the sun won't make up the remaining charge during the shorter darker days.
 

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Always best to try and aim for at least double the battery capacity than your usage, as battery life decreases markedly with increasing depth of discharge/charge. This is a very non-linear effect, so that a battery pack that may last 1000 cycles when discharged over an 80% range (say, 15% to 95% SoC) may be OK for 4000 cycles if discharged over a 50% range (say 45% to 95%). Home battery systems tend to clock up a much higher number of cycles when compared to a vehicle battery, perhaps one or two cycles per day. It makes sense to try and get the longest life you can by installing as much capacity as you can afford.
 

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Always best to try and aim for at least double the battery capacity than your usage, as battery life decreases markedly with increasing depth of discharge/charge
I’d generally agree with this, but for different reasons.

Having a bit more overhead on the battery means you don’t have to worry about sticking the dishwasher or washing machine on at night.
 
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