Adding a solar panel

[tensch]

I am ready to add a solar panel to my 20 TT. The trailer came with a 100W Renogy panel. I am thinking I would like to add a 100W or 200W panel. We don't have any special electrical needs when dry camping other than lights, charging devices, etc.
This new panel will probably be hooked up on the ground. Just wondering if there are any issues I should be aware of regarding connecting the new panel to the existing system and what size panel I will most likely need. Thanks.

[lane_hog]

Not sure if you've moved ahead yet or not, but here's my experience after 15 years...

Our single 130W panel has worked great for our power footprint -- LED lighting and some overnight phone charging, plus maybe 1-2 hours of TV at night. Appliances are all 12V and we rarely use the furnace. We almost always have a generator with us if we get into trouble or need the microwave.

That single panel has always managed to have our batteries topped off by early afternoon. Unless you've got a 110v fridge, that 100W panel you already have may do the job.

I suspect you'll grow tired of the portable. Adding a second panel is easy, but you might not even need it. I'd measure my levels for a couple trips and see how you do.

[pianotuna]

The biggest mistake I made was maxing out the MPPT charge controller. It means upgrading is expensive.

And yes, solar is addictive.

I think the Grape controllers are good value. They have both PWM and MPPT models.

If you place panels in series you needs must use an MPPT controller.

[BFL13]

Controller voltage limit is by total Voc. Voc of a typical 12v panel is 22 volts. Two in series will be 44 volts, and that is at 25C/77F. In the cold the Voc can be higher, so be sure what your controller limit is.

With them in series you will be needing MPPT doing "24-12" (they have a buck converter in them). Tracer, eg has 100v limit that might really be 90 --confusing write up on that. Early model Eco-worthy 20 amp MPPT like mine has 40 volt limit so I can't use it with the 12v panels in series. Ok with them in parallel. Later model Eco-Worthy has a 50 volt limit, so you could use that with two 12s but not three.

[mr_andyj]

Are you against just putting the 2nd panel on the roof?

On the ground WILL allow you to aim the panel directly at the sun, but on the roof will be working all the time and no hassles. I bet you often will not bother to deploy the ground panel...

Put on the roof and run the panels in "series", but make sure your controller can handle a 24 volt system. Panels typically put out about 18 volts for a 12 volt system, so in series will be putting out 36-37 volts. A good controller can take that voltage and drop it to 12-14 volts to charge/maintain your batteries.

Benefit of "series" is ability to use smaller wire from panels to the controller, and you will not need to run additional wires into the camper - all wiring will be done on the roof since you already have a panel ran.

[SJ-Chris]

tensch wrote:
Great thank you all. With this advice in mind I am thinking I will add a 100W panel and run it through the existing controller. So then I am just connecting the two panels to each other? And I assume no issues with two different panel brands, or should I pair the existing Renogy with another Renogy?

They can be different brands, but should be a similar voltage.
If you have a 20 amp charge controller, you should just put 200 more watts on the roof (mount next to your existing panel and connect with Y-Branch cables like this...https://www.amazon.com/OOYCYOO1-Connectors-Branch-Parallel-Adapter/dp/B08RLJMTTD/ref=asc_df_B08RLJMTTD/?tag=hyprod-20&linkCode=df0&hvadid=475689981997&hvpos=&hvnetw=g&hvrand=1936381956844319259&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9032145&hvtargid=pla-1187250666902&psc=1 ) and you are done! No hassle...no storage, etc.

Warning.....Solar is addictive!

Happy Camping!
Chris

[time2roll]

I would match and get the Renogy. Headquartered in Ontario if you are inclined to just run out and pick it up.

[pianotuna]

tensch wrote:
I am ready to add a solar panel to my 20 TT. The trailer came with a 100W Renogy panel. I am thinking I would like to add a 100W or 200W panel. We don't have any special electrical needs when dry camping other than lights, charging devices, etc.
This new panel will probably be hooked up on the ground. Just wondering if there are any issues I should be aware of regarding connecting the new panel to the existing system and what size panel I will most likely need. Thanks.

Match the existing panel. Connect in parallel. Done!

If 200 watts is not enough, and the controller can deal with the extra amps, then add a third identical panel.

[tensch]

Great thank you all. With this advice in mind I am thinking I will add a 100W panel and run it through the existing controller. So then I am just connecting the two panels to each other? And I assume no issues with two different panel brands, or should I pair the existing Renogy with another Renogy?

[Sandia_Man]

We did the same thing and added a Renogy portable 100 watt suitcase to our 200 watts on the roof, at half the wattage it can at rimes out perform roof panels if I occasionally reposition the solar suitcase throughout the day. Peak amps from roof solar occurs for about 4 hours daily, solar suitcase will do 8 hours or more (during summer) of peak amps.

Folds into less than 6" inside zippered hard case, easily stores in our passthrough storage, bed of the truck, or even the backseat. Without all the rigmarole calculations, a general rule of thumb is 100 watts of solar per battery, just as Boon Docker posted above, this works well for him. We use all the amenities in our rig, solar is helpful, thank heavens we have a genny.

[Lwiddis]

Putting out, watching over, moving the panel and putting it away in the late afternoon every day gets old. Better off to put two more panels on the roof. Is your controller adequate?

[time2roll]

If you buy a panel and matched controller then you can attach direct on the battery with no issues.

If you want to run the added power through the existing controller you will need to verify the existing controller is compatible with the total wattage and voltage.

How well does the existing 100 watts work for you? Can you make it through a weekend and keep battery charge above 50%?

[BFL13]

You will want a smaller size panel if you will be moving the RV often and carting the panel in and out to place it outside. A bigger panel on the ground propped up towards the sun is better for getting in the AH, but more for if you are staying in one spot for longer periods as a practical matter for handling. (still need to carry it somewhere when on the road though)

You can add the new by just connecting its controller to the battery bank in parallel with the old set--but try to get the two controllers to have about the same voltage so they add their amps.

Your 200w choice will require an MPPT controller and the one now is likely a PWM, but they can work in parallel on the battery set to the same voltage. A 100 will likely just go on the roof with the other one and share its controller--but-

If the choice is to add the new panel to the old, then you have to check the controller's specs to see if it will do all those amps and beware of series where you add the voltages--the controller's voltage limit (total of panel Vocs) could be reached and fry the controller. Parallel is not an issue for that.

[Boon_Docker]

There are no issues using a portable panel with your existing system.
To give you a rough idea, I have 200 watts and boondock for 30 days at a time. I don't use the TV, just use water pump, furnace at night, exhaust fan when showering, LED lighting for about 2 hours per evening and charging cell phone and flashlight.
My batteries (two-GC2 6volt) are usually sitting at 80% SOC in the morning and are at 100% SOC by early afternoon.