Help with planning on upgrade

[Snout71]

Some of you may know my current set up, 6kw Solar panels (NE facing) H1 5.0-E and 18kw battery storage
Being as the installers put it on wrong side of roof it hasn’t been performing greatly but not too bad. I have only recently been taking advantage of intelligent octopus go, charging on the night and using battery for 12/18 hours day/evening and my savings has been great, though due to not enough battery storage I run out at around 5pm.
So originally I was thinking upgrading just the batteries, but now I am thinking of putting up new solar panels on another roof, originally connecting similar set ups in parallel to make use of the extra storage and getting much better production from the new panels which would face SW.
Should I go ahead with running batteries in parallel, or is it better to have two separate arrays and have a better inverter for this new set up with maybe 40kw storage (EQ4800) of course a lot could be limited to how much I can have on my 80a fuse board and also if I can get an improved g99 from my DNO, but I would like to future proof my home a little more and take full advantage of being able to export
The more I learn, the more confused I am getting rofl

[Snout71]

Apparently according to Fox, having two hybrid inverters is a thing called cross charging, with 2 or more hybrids the6 think that the little amount of power being transferred to the grid (although minimal 24/7) they think it’s an export and start charging the batteries, this then causes the hybrid to pump out more as it thinks it’s a load and the cycle repeats.

Not sure how much this is twoddle and how much of it is correct

[reef]

Do you already have EQ4800s (x4)? If so, you could just get more slaves and run the new SW array on a simple F Series inverter. As long as they are connected by a CT clamp, the H1 will see the generation of the new array and charge the batteries from it. Its the most cost-effective option. The other option is to replace the H1 with a single KH inverter and attach both arrays to that. You'd want at least a KH9 to take advantage of the 4 MPPTs so you have two for each array.

I have a similar setup. I have a H1-5.0-E with 4.8kW of panels on a SE facing roof and got a further 4.62kW of panels installed on the NW roof which run on an F3600 inverter. They are connected via a CT clamp and any generation on the new array is used to charge the batteries or simply exported as normal when the batteries are full.

The only issues you may encounter are that you might struggle to charge 40kWh of batteries on a 5kW inverter in the 6 hour window. For that reason alone you might prefer the second option of the KH, as that can charge at a much faster rate. If I was doing it again I would go this route.

Either way you'll need a new G99 doing though.

[Dave Foster]

Apparently according to Fox, having two hybrid inverters is a thing called cross charging, with 2 or more hybrids the6 think that the little amount of power being transferred to the grid (although minimal 24/7) they think it’s an export and start charging the batteries, this then causes the hybrid to pump out more as it thinks it’s a load and the cycle repeats.

Not sure how much this is twoddle and how much of it is correct

That is only true on the H1 (G1) but the G2 and KH hybrid inverters run perfectly in parallel and share information across a parallel canbus with just a single meter installed on the master inverter. When running in parallel the batteries will charge, discharge and balance the loads naturally amongst themselves. I think Will did an video on his KH setup, i'll see if I can find it.

EDIT: Here you go this is the demo video for his 2 * KH inverters in parallel each with an HV2600*8 stack giving 40kw across the two https://youtu.be/1VssUUe4wsY?feature=shared

This next video is a bit more techy, particularly towards the end but does describe what the KH (and H1 G2) can do in parallel mode https://youtu.be/aot3Y5eSGGw?feature=shared

I'm with @Reef on that one - if you are having more panels on another roof, go with a larger inverter such as the KH and change your batteries - you'll need to get a new G99 issued for it but with the KH7 or 8 you will get the ability to connect 3 strings of solar panels and with the KH9 or 10 you can have up to 4 strings of panels.
The benefit of a large single inverter (over 2 in parallel) is that your losses will be lower during the day (in winter perhaps up to 2kW's per inverter) and you only have to manage one set of charge controls etc.. plus it takes less space and using the EQ4800 you can have up to 42kWh of storage on a single stack of batteries.
Arguably you could also go EP11's as they are very cost effective but at 100kG a battery and needing to be wall mounted they need a lot of wall space if you want the 40kW's.
It's hard to imagine with this setup you would need anything more as it should meet all of your needs, but if you ever decided in the future you want to go parallel and have even more arrays you can add another KH and another battery stack and that would give you access to massive storage.

If you do go with EQ4800's you'll really want at least 5 batteries so the dc voltage for the stack is sufficient to not be affected by low temperatures and so that the maximum charge/discharge current doesn't limit you in any way - the more EQ batteries you have in the stack the better it is.

[Snout71]

Thanks guys.
I am definitely going down the route of the EQ4800 stacks, I like the idea of the k9/10 series of inverters but I don’t think I can unless I am understanding this wrong.
From what I gather you can’t exceed the voltage power with panels I currently have 15x evolution elite 400w panels, which apparently have up 40v each which maxes out the 600A power rating on most (all?) inverters, so I am assuming this would mean I wouldn’t be able to use the other two MPPT controllers?
Like I said, unless I got this all wrong?

So the f3600 could be a solution, maybe I could upgrade the h1 5.0 E to a kh7 series to enable faster charging

Or the other solution of two identical inverters working in parallel

In both instances is it only the one inverter charging/discharging?
Being only single phase I’ll need to be careful not to overload my main board so which would be easier on my circuit? From what I understand parallel they share the workload?

[Snout71]

Actually the EP11 do make a lot of sense

I suppose my main concern is the stress on my fuse board, though I may be able to get them to change the 80a to a 100a fuse

The DNO may well limit what inverters I can have

If I have 2 ep11’s charging up overnight on say 2*k7’s in parallel as well as my EV charging what’s that gonna do to my 80a

[reef]

A single KH10 or 10.5 would serve you fine depending on how large your proposed new array is. Your existing 15x 400w panels on one roof could be split between two MPPTs, leaving another two MPPTs for your new array. There would not be an issue with your house fuse as that would only be 45A charging at 10.5kW.

[Dave Foster]

From what I gather you can’t exceed the voltage power with panels I currently have 15x evolution elite 400w panels, which apparently have up 40v each which maxes out the 600A power rating on most (all?) inverters, so I am assuming this would mean I wouldn’t be able to use the other two MPPT controllers?
Like I said, unless I got this all wrong?

It would be very unusual for a 400 watt panel to have a Vmp of 40V, you tend to see that on the 500+ watt panels - i'm not familiar with this panel myself so cannot speak with any certainty.
I found this specification on the internet for a similarly named panel which has a Vmp of 31.18V and in line with what I would typically expect from a 400 watt panel https://shop.sun-volt.co.uk/wp-content/ ... SERIES.pdf - If it is this panel you would be well within the max DC voltage capabilities of the Fox KH inverter.

Actually the EP11 do make a lot of sense

I suppose my main concern is the stress on my fuse board, though I may be able to get them to change the 80a to a 100a fuse

The DNO may well limit what inverters I can have

If I have 2 ep11’s charging up overnight on say 2*k7’s in parallel as well as my EV charging what’s that gonna do to my 80a

The EP11 has a nominal voltage of 384V and a recommended maximum charging current of 27A - so each battery could charge at 10.3kW if your inverter was big enough - so in effect your maximum current will be decided by the inverter you choose - your existing H1 has a max of 35A so could charge them at 13.4kW but it will be limited by its power to 5kW -so assuming a 230V grid nominal voltage that would be 21.74A, if you add your EV to it that's another 7.2kW (31.3A) so within your 80A fuse.

If you had a single KH9 inverter the batteries could charge at up to 50A (@384V) which is 19.2kW, again limited by the max inverter output to 9kW so 39.13A plus your EV at 31.3A - and so one or both would need to be throttled to protect your incoming fuse.

If you had 2 KH9's each with an EP11you could put a serious dent in your incoming fuse so you would need to set grid limits on both inverters to avoid that.

Note: The EV charger will already have a demand sensor that won't allow it's additional demand to exceed the fuse limit.

All in all with your current 80A fuse you could charge your EV and the EP batteries whether you stay with your H1 or move up to a single KH or go parallel (parallel would need an inverter grid limit set).

You would still be able to charge 2 EP 11 batteries in a 6 hour low tariff period; and even if you added a 3rd EP11 on a single inverter you could fully charge them and your EV together without needing your fuse upgraded.

[Snout71]

A single KH10 or 10.5 would serve you fine depending on how large your proposed new array is. Your existing 15x 400w panels on one roof could be split between two MPPTs, leaving another two MPPTs for your new array. There would not be an issue with your house fuse as that would only be 45A charging at 10.5kW.

The 15 panels are indeed split into two MPPT’s
The downside to sticking with one inverter would be I would only have room for 4 panels on the new array else I would be exceeding the max voltage (600v)

If I used a f3600 like you said for new array I could have another 15 panels, I am guessing that would be another 15a?
2*k7 in parallel would be 42a?

Damn I really wish I knew what the hell I was talking about

[Snout71]

I found this specification on the internet for a similarly named panel which has a Vmp of 31.18V and in line with what I would typically expect from a 400 watt panel https://shop.sun-volt.co.uk/wp-content/ ... SERIES.pdf - If it is this panel you would be well within the max DC voltage capabilities of the Fox KH inverter.

The EP11 has a nominal voltage of 384V and a recommended maximum charging current of 27A - so each battery could charge at 10.3kW if your inverter was big enough - so in effect your maximum current will be decided by the inverter you choose - your existing H1 has a max of 35A so could charge them at 13.4kW but it will be limited by its power to 5kW -so assuming a 230V grid nominal voltage that would be 21.74A, if you add your EV to it that's another 7.2kW (31.3A) so within your 80A fuse.

If you had a single KH9 inverter the batteries could charge at up to 50A (@384V) which is 19.2kW, again limited by the max inverter output to 9kW so 39.13A plus your EV at 31.3A - and so one or both would need to be throttled to protect your incoming fuse.

Yes those are the panels exactly, so room for only 4 more panels
So whether 1*k9 or 2*k9 I would need to throttle back
Would it be fine if I went with 2*k7 rather than k9’s both with ep11
I am trying to understand how you manage to calculate the amps but it’s gone right over my head
Another option could be to ask if my DNO would let me upgrade my fuse to 100a?

My current inverter also runs off another board that’s in my garage so I might need to upgrade that as well as the incoming cable
As you can tell I failed miserably at physics in school, electricity is my weak spot

[reef]

A single KH10 or 10.5 would serve you fine depending on how large your proposed new array is. Your existing 15x 400w panels on one roof could be split between two MPPTs, leaving another two MPPTs for your new array. There would not be an issue with your house fuse as that would only be 45A charging at 10.5kW.

The downside to that would be I would only have room for 4 panels on the new array else I would be exceeding the max voltage (600v)

If I used a f3600 like you said for new array I could have another 15 panels, I am guessing that would be another 15a?
2*k7 in parallel would be 42a?

Damn I really wish I knew what the hell I was talking about

The voltage limit is for a single MPPT, not combined. Its up to 500v on each. If for example you had your existing 15 panels over two MPPTs, one string would be approx 210-220v and the other 240v-250v. You would then have the other two MPPTs free for more panels.

As someone running two inverters I would strongly recommend one single bigger inverter. Its cheaper, less issues and has many advantages like higher battery charge rates.