When things go wrong it is very easy to throw your hands up in the air and call for an expert, but with a little research and working through from first principles, it can be possible to work out what the problem is, and once that has been accomplished, develop a fix. I should say at this point that I am not trained in any of the electrical trades, so I am a complete amateur.
The electronics are giving me a hard time! Woke up on Friday morning and the solar system was not charging the batteries. At all!
Mass panic.
I spent most of Friday trying to find the fault, put everything back on the grid, except the lights, which run direct from the batteries, but after much hair pulling, swearing and discussions with Mike (who designed the new system) still no fix. After continued hassle I decided it was a faulty MPPT, a sort of regulator which matches the panel output with battery requirements. It is one of the more complex ‘black box’ type parts of the system so it was the logical one to blame.
No problems, Mike could order a new one under warranty...… from the Netherlands!!!! Not much I could do over the weekend, just sit and fume. Monday Mike says he has a spare MPPT and is sending right away. (Excelleeeeent!) It arrives Tuesday arvo and I connect it up. It has exactly the same response as the original - shows voltage but no amps - no charge to battery. Which is exceedingly frustrating! Mike makes the point that there is an open circuit somewhere.
The remainder of Tuesday is spent becoming more and more frustrated doing continuity tests with the multimeter showing that everything is OK. Work through from basic principles - What am I missing?????
I am awake at 4:00am Wednesday and spend more time working through the symptoms and possible causes. I did note last night that the MPPT goes dead after sun goes down, ie it is getting no power, so quite probably the issue is the connection between the batteries and MPPT, even though I think there is only wiring between the two.
I give up trying to sleep at 5:30am and head for garage. After inspecting the wiring I realise there is an isolator there I forgot about on the positive cable. I connected multimeter on each side of the isolator and get stupid numbers. I rewired the positive cable from the batteries direct into the MPPT and so bypass the isolator.
IT WORKS!!!!!!!
It seems that the isolator had burned out but it was the bottom terminal and I couldn't see it until I went to remove the wiring to isolate it. I’m glad the neighbours couldn't see me doing a happy dance in the garage at 6:00am.
This was only a workaround to get us charging again and so I got hold of a new isolator after much hassle, because it is 24 volt DC, and now we have a new isolator on both the positive and negative cables and the problem is resolved. (see below)
Please note: I was working on the 24vDC side of the system only, not the 240vAC side of the system, which does require specialised electrical training.
