How to wire my solar panels

[Sportzfann]

I plan to buy 3- 300 W panels for my fifthwheel, I don’t really have enough room for 4 of them. I have a victron 150/45 SCC I have run 2 cond #8 wire to my roof to a w/p 6x6 box and wanted to know options that I can wire my panels, series or parallel ? Approx specs VOC 39.42 ISC 9.86. 305 W.
I wasn’t sure about series wired, it would be close to the max volts for controller. Is one Configure better than another?
thanks, Sportz

 

[Rednecktek]

Series voltage would get you a bit more wattage over the course of the day by hitting that charging voltage earlier and holding it later in the day, but parallel would deal with shading better.

Series is a single wire, parallel requires fuses in each of the panels adding points of failure. A junction box on the roof can solve that problem.

You've got plenty of headway on the voltage so you can go either way with no worries.

Parallel would require at least 10AWG, but at <10a you can use 14AWG in series if wire costs are a concern.

It's really going to depend on where you live as to which is better. In some place like Arizona where there are no trees or shade, series would be the best option. If you want to park under a tree ever then you'll want to go parallel.

I'm assuming this is a 12v based system?

 

[Rocketman]

You can run either series or parallel- either way you will be close to a maximum.

Parallel- Imp of 9.86 *3 = 29.58amps - which is at the limit (30a) of the MC4 connector and branches - but you will be fine. Be sure and fuse each string- there are MC4 fuses.

Series - Voc of 39.42 *3 = 118.26. That is a ways from the 150v max. Get the temperature co-efficient from the panels and run the calculations - so you know how cold until you have to worry. My guess is it will be colder than you want to be in.

Like @Rednecktek says - there are pro’s and con’s to both arraignments. Go with the one that makes sense to you.

 

[Sportzfann]

Thanks for the reply’s I read that a 10% margin for the max voltage is acceptable, so I should be above that. So I can safely go series or parallel I think the shade issue might cause me to go with that parallel configuration.
yes this is a 12V system, with A multiplus II 2x120v inverter 400A lifpo bank.