12V off-grid solar system

sunny1972

New Member
Joined
May 17, 2022
Messages
7
Hi everyone - I am new here and thought I would share my system, I tried to express this as a wiring diagram, excuse the crudity, it was my first time drawing it out like this. There is a typo on the diagram, the batteries are 60ah, not 750ah! it actually reads 750wh on the tin)

I am interested in a few upgrades, like a couple of 300ah LiFePo4 batteries and another 2 solar panels, and perhaps site the MPPT and inverter a lot closer to the solar array for efficiency.

I got this design from a friend and it has been operating now for about 2 years. It powers two offices (a couple of laptops and monitors), it charges some remote 500W batteries which I use to power my WIFI and smaller devices in-situ around the house, it also powers - albeit briefly and on a very sunny day, a distilled water kettle (this draws about 450Wh), my upgrade will allow me to power this more frequently and for more hours.

Thoughts welcome, we have really enjoyed this project and have learnt a lot along the way. Happy to share my experiences further if you have any questions.

All the best
Sunny



Solar System.jpeg

...and here's my real-time readings - it is a sunny day here in Yorkshire (which if you know the UK, is rare :), the daily figure is a little hard to make out, but it reads 0.581 kWh (and in the time it has taken to write this post it now reads 0.655kWh)....all seems to be working nicely.

Readings Realtime.jpeg
 
Last edited:

Bobert

Solar Addict
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Jan 15, 2022
Messages
815
I have never seen a inverter setup on the load side of a charge controller I would certainly verify that the output is rated for the loads you are considering especially if you strengthen the other components feeding it. Usually you would connect your loads directly to the batteries (fused of corse)
 

DThames

Photon Sorcerer
Joined
Nov 22, 2019
Messages
2,330
As Bobert said, the inverter needs to be off of the battery, not off the charger. Also, as you grow the system, the wiring from the charger to the battery needs to be considered. You have those labeled MC4. At some point the amps will be more than an MC4 can handle and you will need larger wire.
 

sunny1972

New Member
Joined
May 17, 2022
Messages
7
Bobert and DThames - thank you for the feedback, not least on the inverter issue and also the MC4s.

I have drawn up a new wiring diagram (again, sorry for the crudity of representation) showing the intended upgrade and rectification of issues.

I have a couple of unknowns:
1. Can I use 16mm2 (AMW 5) for all wiring sections, thought process is to keep everything consistent? I know that my inverter uses 16mm2 cabling (albeit pairs - but I have not got to the bottom of why they supplied two wires for each cable).
2. The fuse breaker on the positive cable, I don't know how to properly size it - I have suggested a 170a fuse as I saw this on a similarly configured system.

Thanks again for reading and considering my system.

PXL_20220519_150018671.jpg
 

sunny1972

New Member
Joined
May 17, 2022
Messages
7
bump - if anyone has some guidance on sizing fuses for the +ve cable, see the above diagram.
 

Bobert

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Jan 15, 2022
Messages
815
bump - if anyone has some guidance on sizing fuses for the +ve cable, see the above diagram.
The design you now have is totally different than your original idea. You are running 12v at the max of it’s capability with that design. If you are wanting a 3500 watt inverter you should go with a 48v system. The cost savings in wire would almost pay for a budget all in one inverter charger. The setup would be dramatically simpler as well.
 
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