Solar Connection Puzzle

[XxAnthxX]

Just out of curiosity........

I‘ve read lots of times that when installing solar panels that the battery must be connected to the controller first then the panel connected or you may cause damage.

Is this the case with all solar controllers?

The thing that puzzles me is.....on portable folding panels with a controller wired and mounted on the back of it....you just connect and disconnect it from the battery, while the panel is connected to the controller.

Some vans (like mine) were pre wired for solar, which basically consists of a common earth and a live cable wired back to an aux fuse in the CBE unit, left in a cupboard for you to connect to your solar controller. Now this, as with everything else gets isolated when the vans power is turned off (yes it means the main power has to be on for the solar to work), but it also means that the panel is already connected to the controller when you power the controller up from the battery.

How is this possible in the two examples above without causing damage......or is it now not the case that the controller has to receive battery power before solar power is connected?

 

[PeteH]

You propose a conundrum, I suspect the answer might lie with the Solar controller needing to have a Feed across it at Battery voltage to prevent a large higher voltage spike on first connection. I have a monitor across the panels output, which on a really sunny day can read well in excess of 24Volts or more. It was dull here most of today and still putting out 17 to 19 Volts. I did not fit the solar`s on this `van but the controller which was used on my last did indeed advise strongly to connect the panel last?. I blew the 20amp one when I fitted the second panel, and had to go to 30amp.

 

[XxAnthxX]

I thought it may have something to do with the controller detecting the battery system voltage (12 or 24) and configuring it’s self to determine the charge rates or something to do with a spike on connection.

But I still don’t get how it’s not applicable to the examples?

I think I need to get out more......

 

[mitzimad]

maybe the controller on portables doesnt turn on until theres battery voltage ? i dont know im guessing

 

[mitzimad]

never had a potable do they come with a plug or a socket on the end?

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[cmcardle75]

Some basic controllers might struggle. But anything decent should be able to cope. It would be easy enough to design a system that wouldn't die and, if I was in that business, I'd make sure my device would cope or I would be getting a lot of warranty claims.

 

[PeteH]

never had a potable do they come with a plug or a socket on the end?

Iv`e only ever had the really small ones 20W sort of size they usually come with a lead and a Plug on one end for the panel and crock clips for the battery. Usually with no controller at all. Aldi where knocking some 15W panels out at one time I have 2, 1is keeping my Classic Car battery charged. the other keeps the Camping Light charged for when we get "outages".

 

[Lenny HB]

Only dual voltage (12/24v) solar regulators need to be connecter to the battery first so they sense the battery voltage and switch to the required mode.
As for your comment about the CBE unit turning everything off I'd be very surprised if it turned the solar charging off. Doesn't really matter as most of us leave the panel permantly on. My van is 3 years old I've never turned the panel off apart from when doing work on the system.

 

[Off da Grid]

As Lenny said above
The portable kits are only for 12v systems so it doesn’t matter,
Would be interested to know those of you that have them, does it say to point away from the sun whilst connecting to the battery.

 

[autorouter]

As for your comment about the CBE unit turning everything off I'd be very surprised if it turned the solar charging off.

I'd be surprised too. You can check if the solar is connected to the leisure battery by measuring the battery voltage when the sun is shining, with no EHU and the engine not running, and preferably with no loads or very small loads. If the voltage is 13.0V or more, the battery is being charged. If solar is the only charging device connected, then it's charging from solar.

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[XxAnthxX]

As for your comment about the CBE unit turning everything off I'd be very surprised if it turned the solar charging off. Doesn't really matter as most of us leave the panel permantly on. My van is 3 years old I've never turned the panel off apart from when doing work on the system.

I'd be surprised too.

Well be surprised......that’s what it does, when the power is turned off on the CBE panel two battery isolator relays disconnect battery.

It’s even documented in the manual, i know some people wire straight back to the leisure battery to avoid having the panel on, but again the manual says do not connect to the battery and you must go through the CBE distribution box or you will have issues.

 

[XxAnthxX]

I’ve had two portable panels, an aluminium folding 100w with a controller on the back, the leads had crocodile clips on which I cut off and put MC4 connectors on and I put MC4 bulkhead connectors on the van so it was just plug in and go.

I also have a very light weight & small 4 fold canvas framed 120w panel with a controller on.....I’ve just left that with crocodile clips on as it gets used on a multitude of vehicles and a solar generator (battery pack).

Nether have ever mentioned in the manual about covering or turning from the sun on connection.

My original thought, of why the connection order, was as Lenny HB said was to detect system voltage to set charging parameters to 12 or 24v.

But was just curious how portables and vans that isolate the battery’s work with them.

 

[Jev88]

Only dual voltage (12/24v) solar regulators need to be connecter to the battery first so they sense the battery voltage and switch to the required mode.
As for your comment about the CBE unit turning everything off I'd be very surprised if it turned the solar charging off. Doesn't really matter as most of us leave the panel permantly on. My van is 3 years old I've never turned the panel off apart from when doing work on the system.

I normally bow to (and am grateful for) your electric knowledge. But my first controller failed to work unless it was battery first and then solar. Found out when I rang previous funster owner why it wouldn't work.

 

[DBK]

Just out of curiosity........

I‘ve read lots of times that when installing solar panels that the battery must be connected to the controller first then the panel connected or you may cause damage.

Is this the case with all solar controllers?

The thing that puzzles me is.....on portable folding panels with a controller wired and mounted on the back of it....you just connect and disconnect it from the battery, while the panel is connected to the controller.

Some vans (like mine) were pre wired for solar, which basically consists of a common earth and a live cable wired back to an aux fuse in the CBE unit, left in a cupboard for you to connect to your solar controller. Now this, as with everything else gets isolated when the vans power is turned off (yes it means the main power has to be on for the solar to work), but it also means that the panel is already connected to the controller when you power the controller up from the battery.

How is this possible in the two examples above without causing damage......or is it now not the case that the controller has to receive battery power before solar power is connected?

It depends on the controller. Victron ones need the battery connected first only on the first connection. Thereafter they remember what voltage they are supposed to work on and the connecting sequence no longer matters.

Portable panels are fixed voltage, generally 12 volt only. If there is a dual voltage version in existence it probably has a switch to flick. Or some very clever electronics not used in dumb MH versions.

 

[XxAnthxX]

It depends on the controller. Victron ones need the battery connected first only on the first connection. Thereafter they remember what voltage they are supposed to work on and the connecting sequence no longer matters.

Portable panels are fixed voltage, generally 12 volt only. If there is a dual voltage version in existence it probably has a switch to flick. Or some very clever electronics not used in dumb MH versions.

Sounds logical

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[autorouter]

I'd be surprised too.

More disappointed rather than surprised, I suppose. I'd be expecting the solar to work while the MH is in storage with everything switched off.

 

[XxAnthxX]

More disappointed rather than surprised, I suppose. I'd be expecting the solar to work while the MH is in storage with everything switched off.

I think that’s why some people ignore the pre-wiring and manual and connect straight back to the battery.

 

[andy63]

Other than the battery voltage sensing that is achieved by connecting the battery first I seem to remember something about the controller been possibly damaged if you had connected the panels and then connected the batteries but in reverse polarity..
The reverse polarity protection built in may only do its job if the battery is connected first.. ie without the panels..
If for some reason the fuse between battery and controller failed you are effectively left with panels connected only and cant see that damaging a controller in the short term anyway..
Andy.