I am in the process of installing a 80watt solar panel on the roof of our Bailey caravan, which will replace the 4 folding suitcase panels we currently use. I will be installing a 10 amp fuse close to battery in the positive feed to the 10 amp solar controller but looking on the internet no one seems to suggest an isolating switch. I could remove the fuse but a switch inside would be more convenient. The reason for an on/off switch for the solar panel installation is that we have a motormover which is connected to the battery via a key operated isolating switch and when it is being used draws a lot of amps and I am thinking that the solar controller will see a voltage drop and to compensate will increase the output charge to battery, so in order not to put the controller under stress each time I operate the motormover I thought it would a good idea to isolate the solar installation whilst getting the caravan off the drive then isolate the motormover and then switch on the solar installation. Has anyone thought about this or am I being too cautious.
I understand your concern but think you are being far too cautious, after all from where could the controller get an overloading current? The voltage needs to drop right down to 8 volts to get to the controllers rated current. And that is only where the sun is giving the rated 80 Watts; I am confident the controller will not be overloaded.
That sounds like the same system that is fittered to my van it was fittered to our van before we bought the van and the person we bought the van off said nothing to us when we bought the van.I found a switch on the side of the bench seat it took me forever to work out what the switch was for I traced all the wireing untill I found a relay with solar panels marked on it but I have no panels so I carn't try it out to see if it all works.Ian
Whilst I have said already I don’t think you need to worry re over current as you can’t generate it and have fused protection anyway; however I see a reasonably elegant solution that if you have the space will cure all.
If you obtain another battery isolator as your mover uses and mount this in the same area as the existing one and wired between solar fuse and controller, then using just the single key you can ‘arm’ either mover or solar cell with that single key, in a ‘safe’ way.
To ensure you don’t forget to rearm the solar cell and therefore not charge, I would have a routine that the key lives in the solar cell switched on; not fool proof in remembering but getting there.
Take your existing key when shopping for the new isolator, there are differing makes but the keys I think are pretty interchangeable.
Certainly the contacts will handle your 80 watts, and not give much power loss!!!
PS; just realised that you dont need to separately wire back the positive to your battery, just link to it on the 'live' on the existing isolator via your 10 Amp fuse.
Thanks for the quick reply, I had thought about putting another isolator switch and using one key but I don't have the space to fit one, these new pwm controllers monitor the battery condition and alter the charge rate as required, but as you say depends on the sun (max 4.8 amps from the panel) I will probably use a 10 amp double pole switch mounted inside the wardrobe so I can isolate the solar power (sun permitting) from the battery compartment for when I remove the battery over the winter. A solar panel is on all the time, even covered up with a sheet polystyrenre while I am installing it was producing 5 volts. I bought the new 80w panel for £99.99 with free delivery, controller £14 free delivery, Sikaflex 291 £10 delivered, a pair of MC4 connectors and made my own aluminium brackets as they were horrendous prices on the internet, not bad when some kits for this sort of installation are over £300.
There is only so much current the panel can provide. I fitted a 50 watt panel about a year ago. Cost me £88 all in. I too made the brackets from some scrap aluminium angle and already had a tube of sikaflex. Now I want a wind turbine on the cheap for when the sun goes down.
I also have a mover, but hadn't even considered the notion of isolating the solar panel for using the mover. The panel and regulator have short circuit protection, so I don't see there being an issue of them going over current.
I have an 85W panel mounted on the roof and have a mover fitted. There is a blade fuse on the positive from the charge controller but no isolation switch for the panel only the mover. I fitted the panel myself and have never had any charge controller trouble. Personally I wouldn't bother with isolating the panel.
Something in the back of my mind tells me that if you remove the load from a pv panel when it is uncovered then damage can occur. I have always assumed that so long as the regulator is between the panel and the isolator then it would not be a problem but now I'm not so sure and think it may depend on the regulator and how it would react to having no battery or load attached.
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As I said earlier, the regulator and panel will have short circuit protection, so having a "live" battery terminal is not a problem. If the terminals touch the regulator will deal with the problem.
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Topic: Solar Panel & Motormover
