Community Forums

Mkaye · 11-16-2019, 02:53 PM

i have 2x100W panels on the roof and the Bogart Engineering SC-2030 solar charger
i want to add another 200W of portable panels
i want to add a port on the side and connect the portable panels in parallel with the 2 on the roof
i bought the RV 2nd hand and have no idea who manufactured the roof panels (i added the Bogart stuff)
do i need to be concerned other than i need 12V panels?

mark

Chuck Q · 11-16-2019, 03:41 PM

Don't think so, will need a separate controller for the portables. Should be water proof though.

HaRVey 74.5 · 11-16-2019, 04:40 PM

I agree that you are better off getting a separate controller for the portable panels since without knowing the limits or capabilities of your current controller or the "open circuit voltage or current" of your roof mounted panels or more importantly, whether your roof panels are connected in series or in parallel, it's hard to know if or how you should wire in your portable ones to an existing system.

Mkaye · 11-17-2019, 05:54 AM

roof panels are wired in parallel
another controller seems like overkill
how much variation in panel output voltage exists out there?

mark

twinboat · 11-17-2019, 06:34 AM

Your controller will handle 30 amps. You will be fine paralleling 2 more 12 volt, 100 watt panels.

With the PWM controller, your roof panels are 12 volt if your RV system is.

Mkaye · 11-17-2019, 06:50 AM

i know the math says i could have more than 30A, but in reality all 4 panels will never be 100%

HaRVey 74.5 · 11-17-2019, 07:15 AM

You're probably ok, since they all are only 100W panels, your individual max amps is only ~6 amps, which when in parellel adds up to ~24 amps which doesn't exceed the contollers 30 amp rating.
There are other issues which impact your total system performance when connecting different panels together since whichever panel has the lowest amperage (when in series) or voltage (when in parallel) will limit the performance of the other panels in the system (unless they have their own controllers). Also panel type will determine how the system will perform (i.e. if the old ones are polycrystalline and the new ones are monocrystaline then the polys will limit the performance of the monos, just like a bad or weak battery will draw down your entire battery bank.)
Renogy (among many others) have info of how to hook up panels for different configurations.
https://www.renogy.com/learn-series-and-parallel/