On Saturday I connected up the solar panels with the MPPT controller - temporarily - to test them. I had bought the kit from HPS
at the IWA National Festival a week before.
I laid the 100W panels on the boxes they came in on the roof and connected them in series. This was easy to do as they came with flying leads, each terminating in a male or female connector. All I had to do was plug the +ve from one panel into the -ve of the other, then connect the long leads from the controller to the remaining solar panel leads.
As well as the MPPT controller, a reassuringly chunky aluminium box with heat sinks on the back ...
... I got a remote display/control unit.
My lovely assistant Jan took some photos of me wiring up the controller. The output cable to the battery bank is disappointingly thin, so I'll probably beef it up a bit.
One major thing for me to work out is where exactly to mount the controller and the remote unit. I want to keep the output lead to the batteries as short as possible, but the batteries are rather fiddly to get to. For the purposes of the test, I had the bright idea of connecting to the other ends of the thick cables, where they go to the isolator switch and the negative busbar.
The wiring here is not very tidy, but there is a convenient flying "live" lead to which I bolted my +ve connection from the controller. (The flying lead is there to provide an emergency link between the domestic battery bank and the starter battery, but it really needs securing better!)
And here is the negative busbar, with my lead bolted on at the top. It looks like it is coloured red, but that is the remains of the insulation when I separated the twin lead a few inches.
When I inserted the fuse in the lead between the battery and the controller I was pleased to see that it immediately sprang into life!
The display indicates that 1.7A is flowing into the batteries, at a voltage of 14.4V. Given the bright sunshine falling on the panels it could have been more, but the batteries were already fully charged. It's very encouraging for the future, though.
By pressing buttons on the panel I could see that the input voltage to the controller was 38.6V. This corresponded with my own measurements beforehand of about 20V per panel off load.
I mentioned my not knowing where to mount the controller and display; perhaps a more difficult problem is how to fix the panels themselves. The kit provides some right-angle aluminium brackets and a tube of adhesive, the intention being to glue the brackets to the roof. Well, I'm not happy with that method. I think I'd rather the panels rest in a frame of some sort, with a security cable, so that they are easily removed for painting etc. I'm not going to bother with angling the panels to catch the sun better: I'm persuaded that leaving them horizontal won't lose me too much power. And I'd "fit and forget".
So, panel mounting, cable routing, controller positioning, remote display fixing ... there's work to be done!