Adding more panels

Itsmcb

Itsmcb

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I currently have a 175watt panel supplied by Bimble solar about 5 years ago. This was an ex-solar farm panel. Its currently controlled by a Epever 20watt mppt controller. This all works well and I don't want to mess with it if I can help it.
I would like to add more panels and have found a couple of Renogy ones that will fit the limited spaces left on the roof. They are an 80watt and a 50watt, both have similar outputs, voltages, etc.
My thoughts are to connect these to a new dual output mppt controller so that my starter battery gets some charge as well. My problem is that I don't know if the new panels will play well with the old one.
Should I just add in the new panels and controller as a separate system and keep the old panel and its controller working as currently? If I do this will both controllers work well together? Both would be connected directly to the hab batteries, nothing going through any built in van controller. Thoughts?
 
If the panels are the same voltage output you can just connect them in parallel to your existing panel.
 
Lenny HB said:
If the panels are the same voltage output you can just connect them in parallel to your existing panel.
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I've no idea what the voltage of the existing panel is, how do I measure this?
Also, if connecting them all to one controller was possible, I would want to change to a dual output controller anyway.
 
Measure the open circuit voltage on a bright sunny day, 12v panels are normally 21 to 22.5v.

You can connect more than one controller to the batteries.
 
Lenny HB said:
Measure the open circuit voltage on a bright sunny day, 12v panels are normally 21 to 22.5v.
Click to expand...
Do I need to disconnect the panel from the controller to do this?

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If the original system is working ok and you were going to buy a second controller anyway ,I would wire the 2 new panels as a seperate system to the new controller and use that to split with your starter / hab .battery
You then don't need to worry about the existing pane voltages or wether they should be wired in parallel or not..If they are not similar you could lose out on output.
 
Jimbohorlicks said:
If the original system is working ok and you were going to buy a second controller anyway ,I would wire the 2 new panels as a seperate system to the new controller and use that to split with your starter / hab .battery
You then don't need to worry about the existing pane voltages or wether they should be wired in parallel or not..If they are not similar you could lose out on output.
Click to expand...
I think that's what I will do. I just have to decide which controller to buy now ....
 
Have a look at the layout of the panels. Common layouts are 9 x 4 (36 cell) or 10 x 6 (60 cell). I would imagine the 80 watt and 50 watt panels are 36-cell, and the 175 watt is probably 60-cell. A 60-cell panel will have a higher voltage than a 36-cell panel, so it would be better to have two separate controllers.

The starter battery doesn't require much charge, just enough to keep it topped up, so a dual output controller for the two new panels would be OK. Alternatively you could get a single output controller, and a battery maintainer like a BatteryMaster to keep the starter battery topped up from the leisure battery.
 
be aware than many MPPT s only put 1 amp to the cab battery so a battery maintainer or battery master may help if you want more than the 1 amp.

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No expert here but I have a full solar kits sitting around and I considered fitting it into my existing system.

Existing system is 3x 80w panels in series connected to 200w mppt controller.

I spoke to tech guy @sunstore as both of the kits are supplied by them.

Sunstore said not to mix panels of different sizes (assume watts) on the same system and to run the spate 200w system with its own controller to the batteries and not mix them.

I consider this too much aggro for the odd times we are off grid so the full 200w solar kit with controller is listed in the classifieds here (shameless plug) so if Sunstore are correct, I would run them as completely separate systems.

I would also use one of these and connect both to your leisure batteries as your starter battery should not need a full panel on its own.
 
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Phill D said:
be aware than many MPPT s only put 1 amp to the cab battery so a battery maintainer or battery master may help if you want more than the 1 amp.
Click to expand...
I think 1amp should be sufficient, I would think that would be around 5amps per day minimum into the battery even in the winter? My starter battery takes about 10days to drop below the level required to crank the engine.
 

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