2018 320 CS-S and adding solar to keep the battery charged if we Harvest Host

Lawyerboy

Sorry in advance if there was a thread in recent years.  Have an AGM battery, relatively new, never used on a trip.  Been too long since we got out of dodge.  So, if I buy a panel, 100w or 2 of them, and what controller, 20 amp, 30 amp?  I understand monocrystaline panels are best and a PWM controller is not as good as an MPPT.  We do not have a set up inside the Tab.  I guess if we were in a field for a night or day and night, could we hook up a panel or two to the controller and then to the battery to keep some juice flowing into it until we get to the campsite with power the next day?  My staff gave me a birthday giftcard and I though solar package was a good idea.  Thank you in advance.  Mark

techietab

I have a 200W Renogy 'suitcase' style panel that works well: https://www.amazon.com/Renogy-200-Watt-Monocrystalline-Controller/dp/B07RFQVB9M/ref=sr_1_4?crid=136PP8O5PAOK0&keywords=solar+panel+200w+folding&qid=1689872279&sprefix=solar+panel+200w+folding,aps,77&sr=8-4

I bypass the lousy controller it came with and connect it to a Victron MPPT 100|20 to charge my dual LiFePO4 batteries. I'm a big fan of the Victron ecosystem. Newer model T@bs ship with Victron components, and it's nice to have a single app to manage all the possible add-ons via bluetooth.

If you go with dual panels, beware that it can make panel positioning a pain. Both need to have as similar angle and exposure to the sun as possible in order to maximize output when connected in parallel (which is the usual configuration for this use case).

Lawyerboy

TY very much.  So panel to controller, controller to battery and simply allow the sun to trickle charge the battery?

pthomas745

What size battery do you have? What trailer?  What fridge? 

The Renogy stuff is much improved over the last few years, it seems, especially with the lighter weight "suitcases".  The one listed above is about half the weight of a 200w "suitcase" compared to a few years ago. Whether or not an MPPT controller in a small system like my 100 watt setup and 100 amp hour AGM is something for nerds to argue about.  A bigger setup?  Maybe.  But, everyone "knows" that MPPT is better, of course. (I have both, and both will charge a battery).  The main advantage I found on MPPT is usually the build quality, and especially in the case of the Victron, the bluetooth monitoring capability of your solar input.  That alone makes the arguments of PWM/MPPT  and which is "better" go away. 

On average, a 100 watt panel, on a perfect day, might crank out 8 amps.  A 10 amp controller will work just fine.  A 200 watt panel on the perfect day, might crank out 16 amps, so a 20 amp controller will be needed.  A smaller 15 amp controller will work with a 200 watt panel, but the extra amps above 15 will simply be ignored.

A slightly larger controller is always a good thing, so even if you buy a separate 100 watt panel, get a 20 amp controller for the if/when you want more solar.

Depending on the trailer, if you have the "SAE" solar port on the side, you can simply use it to connect to the batteries.  If not, you can use several other methods to connect the controller to the battery.  The suitcase style panels can come with no controller at all, so you might plan to get a separate controller that can be placed as close to the battery as possible.  My controllers just sit inside the battery box or close to the trailer when I use the panels, and extension cables are used to get the panels out in the sun.

So, have a look for the SAE port.

And, buy a multimeter, if you don't have one. 

https://www.amazon.com/autoranging-multimeter/s?k=autoranging+multimeter&rh=p_36:1500-2500&qid=1689875268&rnid=1243644011&ref=sr_nr_p_36_5

Lawyerboy

I have a new AGM battery, 12v 92 a.h. at 20hr Duracell.  Have it on a trickle charger.  I have an SAE line to it, so was thinking of getting a controller and one 100w panel to keep it charging if we boondock a day at a harvest host, with intention mostly of getting to a state park for shore power.  So, MPPT controller, 20 amp, and one panel and simply plug the controller into the sae to the battery?

techietab

Lawyerboy said:

I have a new AGM battery, 12v 92 a.h. at 20hr Duracell.  Have it on a trickle charger.  I have an SAE line to it, so was thinking of getting a controller and one 100w panel to keep it charging if we boondock a day at a harvest host, with intention mostly of getting to a state park for shore power.  So, MPPT controller, 20 amp, and one panel and simply plug the controller into the sae to the battery?

Yes, basically. And a 20 amp controller should give you wiggle room for a second 100w panel wired in parallel if you ever wanted one.

Lawyerboy

Perfect.  I surmise the panel to the controller to the battery is simply similar to the trickle charger plugged into power?  If the battery can charge from the sun to power the fan and maybe the fridge a little bit or lights, all good.  TY

techietab

Lawyerboy said:

Perfect.  I surmise the panel to the controller to the battery is simply similar to the trickle charger plugged into power?  If the battery can charge from the sun to power the fan and maybe the fridge a little bit or lights, all good.  TY

Yes, it's practically the same thing. With the trickle charger you have AC to DC conversion, with a DC power feed into the battery. With a solar panel plus controller, you have a DC power feed into controller, which regulates the DC feed into the battery.

When there is a load on the battery (lights, fan, refrigerator, etc), anything generated by the panel/controller will feed the load first; excess will go to the battery. You may also want to invest in a Victron Smart Shunt so you can keep an eye on your load demand vs the current battery state, especially if you opt for a Victron MPPT controller.

pthomas745

The SAE port can confuse people, so this is where the multimeter comes in.  Properly wired from the controller, the SAE port is easy to deal with. 

rcarlson1957

We have two 120W Bluetti portable panels (very lightweight) and I installed a Victron Smart Shunt, battery temp gauge, 100/20 MPPT solar controller connected to a Ampere time 100ah lithium battery all in front tub for when boondocking. I use one panel with a quick connect to the solar controller to keep camper battery up to speed. Use other panel in conjunction with a Bluetti AC50S 500wh solar generator to power a small external ICECO GO20 refrigerator/freezer.  Works well for us after 2 years of use. 

Homebodyatheart

You might be overthinking this a bit. First, I think having a solar panel set is a great idea! I have a 125w ACOPOWER setup, super thin, weighs about 8 pounds. I’m currently at a Harvest Host site, and use a cpap. I have an EcoFlow power station, like a Jakery. I used it to heat water in my electric kettle (4%used) had my phone plugged in for a while (but put it back on the Tab AGM for the night) and used my Cpap for over 8 hours. All that and I used 34% power from my EF. I’m over the moon happy about my usage! BTW I had a group 27 battery installed before I took delivery in early 2017, am usually on shore power, was 12.7 when I arrived here, and am at 12.6 this morning. My fridge is on propane. Good luck with your decision! 

Lawyerboy

Ty all. I bought the Reno by suitcase thank you all.  I bought the renogy 100 watt suitcase and it comes with the 20 amp controller.  It will get me started.  And, just renewed harvest host membership.  We must get back out there once the weather cools a bit