Single Phase home Solar and Battery Storage installation

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1

My installation consists of;

3.7 Kw front roof with a Sunny Boy 4000
Feeds directly through a meter into AC Out critical loads.

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Whole house is classed as Critical Loads so nothing is in AC Out 2.
Cerbo GX runs the entire system.
2 parallel configured Multiplus 2 5000 70.

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Top roof (flat) with 8, 565w JA Solar panels.
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These are divided into 2 strings and each into their own Smartsolar 150/ 70.
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A Lynx Distributor connects the DC system together. The wiring is a little untidy but I’m still considering moving the system partly into the garage…
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This charges 8 Pylontech US5000 batteries.
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I have been running a single multiplus up until the other day, as last time I tried to set up the parallel, I f’d the whole system up. I now found the balls to try again, having done a little more research and with a few teething problems such as batteries charging straight away, the system now seems great. I did approach 3 companies, asking them if they would be able to configure my two Multis, but they all ignored me :face_with_symbols_over_mouth:. My batteries charge at night to 85% on off peak rate. With just a single multiplus, the 5hrs of cheap electricity was not enough to get it that high but with 2, it’s done in no time!
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The system is under the stairs and gets rather warm so I fitted an extractor into the garage. Unfortunately there was no way for the air to get in so it didn’t really do a lot. I thought the heat in that room would help heat the house, but it’s insulated so didn’t. I decided to try to help the inverters cool by fitting pipes directly from under the floor into their intakes and what a difference! They are happy chappies! The whole house runs off the batteries until they are flat (rarely) so my only grid consumption now is night time cheap rate.
My plan for the very near future (next couple of weeks) is to replace the top 4 panels of the front roof with 4 x 620w and the bottom row of the front roof with another 4/x 620w panels. Just replacing these panels will add 2620w to my system. I need to do some calculations first, as I can only export 3.7Kw and the front roof is currently AC coupled, the top roof DC coupled. I will need at least one more Charge Controller, but will need to re-configure the ones I currently have as they are slightly oversized.

2

You have wired your batteries into two groups of four batteries each. Each group is connected to the bus with two pairs of wires. This results in the batteries being connected with unequal wire lengths.

It would be better to wire the batteries into four groups of two batteries. Each group is then connected to the bus with two wires. One battery in the group receives the positive connection and the other the negative connection.

3

There is nothing wrong with this method, pylon cables are a uniform length and using both connectors is common practice and recommended by pylon.
Each stack has 2 +'ve and 2 -'ve connections, one at the top of the stack and the other at the bottom, so the flows are balanced.
Splitting them out just creates more wiring on the busbar and in this config doesn’t improve anything.
The packs are symmetrical which is what matters and this is a tried and tested method which works well.