Solaredge with Multiplus-II 10k for East-West 8 to 10kWp system, expansion to South-East-West

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bladerunnervf asked Jan 28, '24

Solaredge with Multiplus-II 10k for East-West 8 to 10kWp system, expansion to South-East-West

Hi, my simple headline question is can I do this with Victron + Solaredge?

I hope I haven't missed the answer, I may not be searching with correct terminology for Victron systems, please redirect me if need be.

Planning a system presently, which I will get an installer to fit, however I wished to check in advance that this is feasible, if someone could assist please...

Thinking East-West system, possibility to extend to South-East-West

East : 10 panels, ~4.3 to 4.8kWp, concrete roof tile ~30deg pitch

West : 9/10 panels, ~3.8 to 4.8kWp, concrete roof tile ~30deg pitch

Future South - may fit 6-10 panels, wall mounted

I have some shading which the more I think about is drawing me towards a Solaredge based solution

East : shading factor ~0.90

West : shading factor ~0.82

PV inverter:-

For East-West : 2x strings, one from East, one from West into a Solaredge inverter, poss a 10kW HDwave

Later, for South add a second Solaredge inverter, poss a 5kW

Inverter:-

Victron Multiplus II 10kVA version, + cerbo GX and monitoring screen

Batteries:-

I know solaredge do 10kWh battery but at £6500 each it's expensive

- linked to the multiplus - starting 10 to 15 kWh, poss increasing to 30kWh

- Fogstar 15kWh rack is much cheaper than solaredge battery,

- or maybe several Pylontech US3000C / 5000C

Informal chat with the DNO suggest 8kW export would be likely to get a thumbs up, maybe more?

I used a freely available PV tool to draw something up, assuming 3x Pylontech US3000C. The tool may not take Victron features/capabilities into account or show where the CT should be?

I see the most similar Victron diagram is the "grid-inline topology" from this link (forum won't let me attach a snip)

https://www.victronenergy.com/upload/documents/Datasheet-MultiPlus-II-GX-inverter-charger-EN-.pdf

Q) would I be able to more battery to maybe 30kW like this ?

Q) would I be able to add more panels (South wall) by adding a second solaredge inverter, assuming a master-slave connection for the solaredge ?

Q) In by ignorance / naivety is there anything massively wrong with this approach ?

Thanks for taking a look

Multiplus-II Pylontech solaredge

capture-victron-10kva-solaredge.jpg (39.1 KiB)

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Answer 1 · 2024-01-28T15:03:02Z

nickdb answered · Jan 28 at 03:03 PM

The community tends to discourage design topics, as per our terms, and encourage users, especially for more complex systems to engage with their installer or a Victron supplier for professional advice.

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Answer 2 · 2024-01-28T15:48:28Z

bladerunnervf answered · Jan 28 at 03:48 PM

Whilst I can well understand a "we can't design it for you, it's your responsibility to use the professionals rather than take some bloke off the internet's word for it " sort of disclaimer, (funnily enough I nearly added a statement to say I would be talking to installers) I was hoping that being helpful by supplying sufficient background and context and hopefully clear diagrams for the question it might facilitate a response from other users such as "yeah I've done that, works really well", or "no devices x and y can't communicate, so it will ..."

I've just read the forum terms, perhaps I added too much context and made it look like a "multifaceted issues involving system design" type thread in order to make the question clear as I could.

At it's heart it's really just a can I use solaredge with Victron type of question...

hope this helps

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ejrossouw commented · Jan 28 at 11:35 PM

Worth a read. https://www.victronenergy.com/live/venus-os:gx_solaredge

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bladerunnervf ejrossouw commented · Jan 31 at 04:05 PM

Thanks for the link :-)

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Answer 3 · 2024-02-01T20:24:03Z

daniel-feist answered · Feb 01 at 08:24 PM

If you don't already have Solaredge inverter, using Victron MPPT's may be a more flexible/extensible approach. More efficient too as you don't go DC->AC->DC again when charging batteries from PV.

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sharpener commented · Feb 03 at 03:25 PM

Yes +1 to that. Also 10.6 kWh of battery is quite small for a 10kVA inverter (as @nickdb told me when I was installing my original system - have now upgraded by 50%). And with your proposed configuration your solar inverter(s) will not work in a blackout.

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daniel-feist sharpener commented · Feb 04 at 05:02 PM

It's not the battery size specifcially that is a concen, rather max charging amps, when using ac-coupled inverter on AC-out. Can have a huge battery, but if the BMS supports only a limited charge current for some reason you have a problem. You also need to set up frequency shift contol etc.

With victron MPPT you avoid all these complications and getter better efficiency to boot. So only real question/concern is shading I think.

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bladerunnervf sharpener commented · Feb 04 at 04:22 PM

@sharpener

Hi sharpener, thanks for the tips,

I shall need to read up on minimum battery, I think I've seen doc on victron - pylontech compatibility somewhere, which I presume would apply in general for other makes of battery.

What is missing to enable operation in a power cut - a changeover switch? I thought the multiplus had capability to be used in a power cut, 20ms switchover etc.?

I'll be getting some victron based quotes soon, I'd like to be at least a semi-intelligent customer!

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delf67 bladerunnervf commented · Feb 04 at 04:32 PM

Your PV inverter needs to see a grid to work. Therefore it has to be on the output side of you MP, not the input side. The MP then becomes the "grid" as far as the PV inverter is concerned during a blackout.

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delf67 bladerunnervf commented · Feb 04 at 04:36 PM

Just looking at your diagram again, that is the output of the MP you've shown, and you don't have a grid input to the MP?

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delf67 bladerunnervf commented · Feb 04 at 04:38 PM

Sorry, to clarify: The way your diagram shows it you would be trying to backfeed the entire grid from your MP.

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sharpener delf67 commented · Feb 05 at 10:54 PM

Both input and output are in fact bi-directional so there is no problem with the arrangement in the OP's diagram. Except that it does not comply with UK regulations, as the IET Code of Practice requires that the inverter is protected with an RCD which it does not share with other final circuits.

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delf67 sharpener commented · Feb 07 at 07:01 PM

Except that the output from the inverter would be live if the mains fails, so backfeeding into the grid. I would say that was a problem.

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daniel-feist delf67 commented · Feb 07 at 08:22 PM

No! If mains fails AC-IN disconnects.

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delf67 daniel-feist commented · Feb 08 at 05:00 PM

Read the post before chiming in. He said there was no problem with the AC OUT being connected to the consumer unit, not the AC In. (Well he actually said it was no problem with either the AC Out or AC in as they are both bidirectional).

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sharpener bladerunnervf commented · Feb 07 at 02:41 PM

For the PV to continue working during a power cut it needs to be connected to the AC-Out of the Multi, as the internal relays on the AC-In side disconnect automatically on Loss of Mains.

Search on here for the 1:1 Rule as this limits the amount of PV on AC-Out to the nominal rating of the Multi. PV attached via an MPPT to the battery is however exempt from this rule as the Multi can control it separately.

Beware that Pylontech batteries have only 15 cells unlike nearly all others which have 16. So the voltage settings you need are very different.

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Answer 4 · 2024-02-03T00:17:09Z

@Daniel Feist

Sadly I have nothing at the moment !

Agree about the victron MPPTs being flexible, it's a great mix and match system in principle

My main reason for enquiring about solaredge + victron compatibility is the shading question and trying to get the most out of the system, especially at the shoulders of the season and west facing evening summertime shading.

I don't know if the victron MPPTs are up to the job w.r.t. shadows and to warrant the extra expense vs Solaredge ?

I had understood the solaredge system would work better with shading / shadows as it MPPTs on each panel rather than MPPT on each string

shading factor East roof ~0.90, West roof ~0.82, South wall ~0.84

It's quite subtle though,

East side shading has two contributors -

i) tree to the east affecting 1st hr or so Apr-Aug, e.g. before 6am in June

ii) rooflines SE to SSW affecting Nov, Dec, Jan, Feb to about 9am

West side shading has two contributors -

i) a hard shading patch from gabled roof line end Nov to start Feb affecting 1 or 2 of 10 panels

ii) rooflines and tall trees from SW to WNW reduces autumn afternoon (starts 1430 mid-oct) and summer evenings, produces shadows moving across roof with sun path

South wall shading again has two contributors

i) rooflines SE to SSW affecting Sep-Mar (direct light only 1100-1300 on 25th Dec) maybe better if I can get panels higher up

ii) nearby tree to SW affecting Nov, Dec, Jan, Feb. (2pm onwards at start Nov) and further trees and rooflines from SW to WNW

Solaredge Cost wise : £5500 for E-W, £6810 for S-E-W (excl panels)

Solaredge 10kW HDwave for East,West about £1700

+ 20x optimiser £1200

+ 0 x DC isolators £0

+ Victron Multiplus 48/10000/140-100 about £2600

= (1700+1200+2600) = £5500 for E-W,

Add South : £950 for 3.5kW HDwave + 6x optimiser £360 + 0 x DC isolators £0 = ~£1300,

=(1700+1200+2600+950+360) = £6810 for S-E-W

(hmm, need AC isolators before input to HDwave ?)

Victron Cost wise : £4760 for E-W, £5765 for S-E-W (excl panels, cables etc)

Victron 450/200 for East,West about £1500

+ Victron Multiplus 48/10000/140-100 about £2600

+ 4x DC isolators ~£120

+ Cerbo GX MkII £270 + Touch 70 screen £270 = £540

= (1500+2600+120) = ~£4220, + 540 = £4760 for E-W

(split panels into 5/5 East, 5/5 West to use all 4xMPPTs of the 450/200 ?)

South expand 6 panels 430W, maybe 9?? = Max £1005 for a MPPT 450/100

1x 450/100-Tr with 1p6s to 1p9s, but the startup voltage is ~160V according to MPPT calculator or 120V according to the datasheet (which correct?), not so good in winter? £935

+ DC isolator £35 + AC isolator £35 = £935 + £70 = £1005

Alternatively for south

1x MPPT150/70 with 2p3s or 2p4s (parallel good or bad for shading though?) ltd to 4000W OK £330

2x MPPT150/35 with 2x 1p3s = 2x £165 = £330 + 2x DC isolator £70 + 2x AC isolator £70= £470

1x MPPT150/45 with 2p3s (good or bad for shading though?) ltd to 2600W (433W each) Tight/No

A Vic 250/100 would need panel Voc < 38V to take 6 panels and allow for -10degC. Tight/no good

Victron total for S-E-W = £4760 + £1005 = £5765

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