Is my installation series or parallel?

[johndorst]

Quick question (I hope). Many years ago we had a single Zamp 100W panel installed and connected via the built-in solar wiring on the roof of our 2011 20FB. I want to add portable panels and was given a couple 35 watt panels. I need to connect them the same way that the roof panel is connected - series or parallel. Is a single panel parallel by default?

[jeffb831]

A single panel is neither. It takes 2 or more panels to be either serial or parallel.

[Wazbro]

Originally Posted by jeffb831

A single panel is neither. It takes 2 or more panels to be either serial or parallel.

True, though a single panel would have the same voltage as a set in parallel. So as far as matching it would match the parallel. Unfortunately not all panel manufacturers set their panels up at the same voltage, so you need to make sure the voltage matches. Different voltage panels would at best not be as efficient.

[johndorst]

So, the mounted panel has a 100 W rating, the portable panels I was given are much smaller, 35 watts each. Owing to the disparity, I would likely need to insert a switch of some kind to use one or the other, not both at the same time.

My plan was when parked in shade, we could pull out the portables to get sun. What I've read says that if they only work as well as the weakest one in the set, so if the roof is completely shaded and not generating, then the portables won't be able to generate any either. Only by disconnecting the roof will the portables be able to recharge the batteries.

[LNBright]

John,

Such is the case if all of your panels are going through a single controller. If you add another solar controller to handle the ground deploy solar, it doesn’t matter if the roof is shaded.

[johndorst]

Originally Posted by LNBright

Such is the case if all of your panels are going through a single controller. If you add another solar controller to handle the ground deploy solar, it doesn’t matter if the roof is shaded.

Good point - hadn't thought of that option. Thanks!

[richard5933]

Originally Posted by johndorst

So, the mounted panel has a 100 W rating, the portable panels I was given are much smaller, 35 watts each. Owing to the disparity, I would likely need to insert a switch of some kind to use one or the other, not both at the same time.

My plan was when parked in shade, we could pull out the portables to get sun. What I've read says that if they only work as well as the weakest one in the set, so if the roof is completely shaded and not generating, then the portables won't be able to generate any either. Only by disconnecting the roof will the portables be able to recharge the batteries.

I would suggest that having a switch between the panel(s) on the roof and the solar charge controller is always a good idea. You never know when you'll need to work on something in the system and want to be able to shut down the incoming current. In this situation though, I don't believe having a switch will make a difference.

Regarding the parallel/series question, here's a quote from the Battleborn website explaining an advantage of parallel wiring on solar panels:

Solar panels in parallel operate independently of one another and therefore are the best option for mixed-light conditions. If shade covers one or two of your panels, the remaining panels in the array will continue to generate power as expected.

Here's the link to the page I took it from.

I believe this answers your question. Install the new ground-deployed portable panels in parallel with your roof-top panel.

[uncle_bob]

Hi

There are no perfect answers to this. One typical answer is to simply put the "other" panels on their own controller. Since they are portable, feeding them in through the stock "Zamp" connector is how it often gets done.

If the plan is to mount the new panels on the roof, going with a mix of power levels and fabrication technologies is not a good idea. They are unlikely to match up / play well together.

Bob