Forums, Electrical Systems, Navigation and Safety equipment, Solar Panel setup

Speedwell at 07/03/2016 19:33:17
I am new to solar panels. Speedwell is fitted with a deck mounted solar panel and Westech controller. The setup appears to be that the controller is connected to both starter and domestic battery banks but that it is configured to only charge the domestic. Is this usual?

Keny at 08/03/2016 13:49:22
I have two solar panels screwed to the deck just forward of the spray hood. They don’t need a controller and are connected together, and to both batteries, via a schottky diode splitter.
I have found this to work fine
keny

CO923 at 11/04/2016 15:33:02
Keny, sounds interesting, what power and max voltage rating are your panels please?

Speedwell, that sounds odd but I don’t know enough to comment usefully. Can you switch the controller output manually between the domestic and starter batteries? In which case maybe you have to do that?

Keny at 12/04/2016 10:51:33
They are 2x Marlec/Spectralite, 20w each, semi-flex. panels. The open circuit voltage is around 16v but even when fully charged the trickle voltage pulls this down to around 14.5v so no need for a regulator which can only reduce their charging capability. Batteries are 60ah & 100ah.
keny

CO923 at 12/04/2016 14:23:11
Keny – Great, many thanks.

Speedwell – I asked Sterling about how to add solar panels to a system with a Sterling charger. Charlie Junior recommended putting the solar panel outputs across the domestic batteries “and relaying the domestic battery output to the starter with something like a matching relay”. I understand the first but not the second part of this advice. However, with a manual selector for either or both battery banks, it’s possible to use the domestic batteries to start the engine if the starter battery hasn’t enough energy left. This might be what was intended on Speedwell.

caramorsimon at 21/04/2016 22:20:40
a matching relay is just one that connects the 2 battery banks together when a charge voltage is present.
usually it’s called a voltage sensitive relay.
you may find that the controller was just connected to both battery banks to ensure its always powered up: there may have been a concern that if it was attached to the flat domestic battery only it wouldn’t charge it properly (the concern may or might not have been valid – you’d need to check the instructions to see)
as keny says, you don’t need a charge controller if your banks are large cf panel size. marlec prefer 10:1 before needing a controller though. I have (from another supplier) a controller around that ratio – the batteries are full in the summer but it may well be unnecessary in spring/autumn. you can always put in a bypass switch to get both or just try the alternative!

Galatea at 27/08/2019 01:29:12
In order to avoid having to run my engine just to charge batteries, I think I’ll need a minimum 100W, preferably 200W, panels. I’m considering mounting them on an arch just aft of the backstay. Does anyone have anything like that on a Contessa 32? Or is this just too much weight and windage?