nav[aria-label="Primary Navigation"] { padding: 0; & ul { list-style: none; width: 100%; display: flex; flex-direction: row; justify-content: start; align-items: start; gap: 30px; padding: 0; & li { margin: 0; } & ul li { list-style: none; } } }

Child Item

Inverter for 4 strings

...Ghost...

Happy Easter Ladies and Gents.

I now have an 8.62kWp system consisting of 4 strings split between a 5kW hybrid and a 3.6kW string inverter, but I already have in mind to get a bigger inverter and NC7. I am thinking I would prefer a Solis 8kW or 10kW single phase hybrid.

String 1 is 4 x 435W Jinko Neo with optimisers. North facing main roof. Hybrid inverter.

String 2 is 8 x 435W Jinko Neo. South facing main roof. Hybrid inverter.

String 3 is 4 x 450W JA Solar. South facing flat extension roof angled about 20 degrees. String inverter.

String 4 is 4 x 450W JA Solar. North facing flat shed roof angled about 10 degrees. String inverter.

The North panels on the main roof are the only ones with optimisers.

Here's what my (possibly imaginary) problem is. I would prefer a Solis Hybrid 8kW or 10kW inverter, because I am familiar with the 5kW hybrid already. Looking at the PV inputs, it takes 4 pairs of them. However, it seems to only take them in 2 pairs of 2 to accommodate split larger arrays, rather than 4 truly separate strings like my setup.

See image here

Can I connect the 4 strings into any of the 4 input pairs above?

So, lets say main roof panels populate the inputs in the PV1 box and the extension and shed strings populate the PV2 box?

I am thinking no, because while the house panels might be OK due to the optimisers on the North facing panels, there would be an issue with the extension and shed strings being put into PV2, because they are at opposing directions and inclinations and neither string has optimisers.

If I am correct in my thinking, would adding optimisers to either the extension or the shed string allow me to put them into the PV2 box?

Maybe I am totally wrong and it's perfectly fine to add the 4 strings as they are without optimisers?

Thanks for looking.

Find more posts tagged with

Quick Links

Comments

oaklands

verify how many MPPTs the inverter has.

If 2 then each shared pair should have identical strings (kWP & orientation/tilt)…also verify the max current on each MPPT

If 4 MPPTs then each string is independent.

Some sunsynk/deye have a 2+1. the double string MPPT does support double the current.
I think I saw more recent ones with 2+2 MPPTS

Have you looked into using 600kWp+ panels as a possible solution? Newer inverters can handle the higher voltage/current from these larger panels.

...Ghost...

https://www.boards.ie/discussion/comment/123374255#Comment_123374255

It's really just a 2MPPT inverter, but I have also found a 12kW with 6MPPTs. S6-EH1P12K03-NV-YD-L

I know another solution would be to just get the 8-10kW inverter and keep using the 3.6kW string. This would be an easy swap with the 5kW and would let me import/export more kW while pushing me for the NC7. I would just prefer a single inverter solution, cost depending, but I suspect I will likely end up simply upgrading the 5kW to 8 or 10 while keeping the 3.6.

slave1

Think carefully on the NC7, they could refuse and you'd have to take panels down and take an inverter out of use etc

...Ghost...

https://www.boards.ie/discussion/comment/123379607#Comment_123379607

Are they in the habit of refusing applications for small increases? I could understand if I was going for 20kW+, but I'm proposing a small increase if I decide to go for it.

Big Lar

Why do you have to change out the inverters, can you not just apply for NC7 with the two inverters you have and up the export settings?

ECO_Mental

https://www.boards.ie/discussion/2058406914/inverter-for-4-strings

Have you thought about a MPPT solar charge controller for one or two of the strings. They are relatively inexpensive are efficient (about 99% I think) and they don't effect your NC6. This could also help solve your problem of not being able to fill all that battery storage you have..

...Ghost...

https://www.boards.ie/discussion/comment/123380931#Comment_123380931

I haven't had a proper chance to check, but I think the 5kW hybrid is actually limiting the export, as it seems to max out at that figure. I'm waiting for my datalogger to be paired to the small string inverter so I have all the data.

While I could technically have the NC7 processed with the 5 and 3.6kW inverters, I am still limited to 5kW demand on the storage to house unless I have a larger inverter. 8kW would do me after the electric shower is ripped out. 10kW would be nicer. But only the 12kW I listed above seems to have the 4+ MPPTs to hook up all my strings. It would also mean I wouldn't need a rectifier to help the batteries charge in the small hours.

...Ghost...

https://www.boards.ie/discussion/comment/123381119#Comment_123381119

Not in any great detail, because I prefer to export during the sun hours unless the battery is 50% or lower and a dull day is expected next day. I would have gone for one of these if I only wanted to store the solar energy.

Buffman

How many more panels are you planning or is the 8.82kW total your max?

ECO_Mental

https://www.boards.ie/discussion/comment/123381137#Comment_123381137

Should it matter..you are not loosing energy only deciding later when bedt to discharge, you could set up an automation to invert from the battery during the day to export if you are near full with the battery anyway

...Ghost...

https://www.boards.ie/discussion/comment/123381160#Comment_123381160

I can fit another 4 on my north roof, adding another 1.74kWp using the same jinko 435W panels.

https://www.boards.ie/discussion/comment/123381171#Comment_123381171

Automation is on my to do list. I haven't got that far yet. Definitely a must do.

Buffman

https://www.boards.ie/discussion/comment/123381197#Comment_123381197

Ok, well the North facing panels will never give 100% and when they're 'high' the South facing will be 'low' and vice versa so you'll never be producing total max power with different orientations, so I think a 10kW inverter might be overkill, I doubt your current setup is having to clip much if anything already.

On the face of it I don't see how the sums will work out, non-refundable €1k on the NC7 and possibly €1.5-2k on a new inverter, even selling the old ones for a few €100 still means a big outlay.

Unless you've a big battery and plan to be just importing and exporting at 10kW overnight for FIT? Even at that I'd guess payback period would be substantial.

If it's really a path you want to go down, don't buy any kit until they come back with a figure on the NC7, they may only bump you up a couple of kW or might refuse altogether depending on local infrastructure.

If you haven't already, have a read of the NC7 thread here for an idea of the potential issues.

...Ghost...

https://www.boards.ie/discussion/comment/123381811#Comment_123381811

You're correct about the overkill on solar side. I'm not planning additional panels and the only reason I was looking to a Solis 12kW inverter was the number of MPPTs to accommodate my 4 strings. I could technically fit another 2 panels on the rear of shed facing directly south and the same idea where my kitchen extension meets the main house, but I'm not bothering with that.

Rough sums: I have about 40kWh of battery storage. I export about 10kWh each evening from the battery averaged out over the year. So say 3,500kWh annually. I would expect to double that with a larger inverter and by adding another 15kWh storage, bringing my outlay to around 4.5k euro. So at 20c for export, 3.5k units is 700 euro. Payback would be 6 years. I believe I would export more, but I'm being conservative. Still worth thinking about. Thanks.

slave1

You're going to have losses to account for…and FIT could be 4c this time next yr

...Ghost...

https://www.boards.ie/discussion/comment/123385853#Comment_123385853

Ah now…that's a bit pessimistic.

I've just got my rectifier installed and I installed the CT clamp in my charger, so load management should now work. Only thing left is to get the Sonoff Wi-Fi switch connected to the APP, so I can schedule the timer! It doesn't seem to want to connect.

Once I get rid of the electric shower, the loads should rarely go over the 5kW max of the inverter.

TrueBlue1000

https://www.boards.ie/discussion/2058406914/inverter-for-4-strings

I am in the same scenario. I recently priced an 8kW Solis from Solartricity., more than big enough for the planned PV. But, will have varying strings. And as you say, the 8kW has the 2 MPPT limitation. So, 12kW might be the way to go. Out of curiosity, is the 3.6kW inverter capable of exporting to grid?

...Ghost...

https://www.boards.ie/discussion/comment/123545833#Comment_123545833

Any inverter can export afaik. If 1kW is being generated from the panels and converted to AC by a 3kW inverter, the energy will either go to the house load, or if there is less than 1kW load, it will be exported. In my case the 5kW inverter limits the export of both to 5kW max. If both are generating peak (5kW + 3.6kW) the 5kW goes to the load/grid and 3kW goes to battery if there is available space. The other 0.6kW is clipped. I have seen this a few times.

TrueBlue1000

https://www.boards.ie/discussion/comment/123546171#Comment_123546171

I was wondering how you were restricting to NC6 levels. The aforementioned 8kW or 12kW inverter pushes us into NC7 which I see you are considering.
I'm now planning to use Victron MPPT RS 450/200-MC4 which has 4no. MPPTs and cheaper than the 12kW inverter.

Planned Control Philosophy:
With Solis S5 only and Victron MPPT to batteries, use Home Assistant Solcast to predict when to stop exporting (and start storing) so that there is enough to get to 2am EV recharge.
When excess PV forecast, keep exporting batteries from say 70 to 50%. 70 to 100% charging used to minimise clipping of MPPT.
Approaching midnight, HA re-calculates and exports excess before 2am without importing with peak rate.