RV Solar Design Advice

[danphillips]

I have a new to me 40ft motorhome and want to add solar and LFP.

The RV has 6 new 6v lead acid batteries for the house

I have 12 CALB 180ah LFP batteries I can configure as 3p4s from another project

The RV has a integrated power management system, 12v/2000w Magnum inverter and 7.5kw generator

My thoughts are to build a separate 12v LFP system and use my 2 existing Victron 30a B2B chargers to maintain the lead acid batteries.

The LFP batteries would be charged either by solar and/or 2 Victron IP22 30a 12v chargers (when tied to dock power)

I know this is not the most efficient configuration, but will utilize existing equipment.

Looking for recommendations on other configurations and the best solar panels for mounting flat on an RV.

I’d like to get 1200 - 1600 watts of solar and a Victron MPPT SSC. FYI — the RV is pre-wired for Solar with 6ga wire.

Any help would be appreciated

 

[Crowz]

I'll let someone with more experience on this come up with their recommendations on what to buy I just wanted to insert a warning on the roof part. Be very careful when you go installing the panels on the roof. My 36 foot trailer is pretty much ruined now from roof damage that happened after I bought it from a tree limb damaging it and me not catching it.

Just be careful on panel mounting

 

[Solarcabin Channel]

Does the RV have a DC converter?

First thing I would do is check the specs on the RV DC converter as most older RVs do not charge at the higher voltage needed for LFP batteries.

They can still work but batteries won't get fully charged, They sell RV converters on Amazon designed for LFP.

Also keep in mind LFP won't charge below freezing so you may need an external heating pad and insulation or internal heated batteries in cold country,

 

[justinm001]

What are you planning on connecting the lfp to vs the lead acid batteries?

 

[danphillips]

@Solarcabin Channel - the RV alternator will power the magnum inverter/charger which I can then use the LFP battery chargers while traveling. Also, the alternator will charge the house bank while under way.

@justinm001 - LFP’s will only be used to to keep the lead acid charged. Once the new LA batteries die, I will upgrade the entire system to LFP or what ever new battery tech may be available.

 

[danphillips]

Any suggestions for solar panels - size / MFG?

 

[MisterSandals]

Any suggestions for solar panels - size / MFG?

Look for big cheap panels in your area. Craigslist and Facebook market are good places to check.

If you post your city or area code maybe someone will point you to a good deal nearby.

 

[danphillips]

I’m in southport, nc 28422

Question, is several (6) Solar panels better than a few larger panels?

 

[RoadTurtle]

With that much roof space, go big. Plan to use a rail system to mount the panels, and push them all the way to the outside edge. Leave some walking room to get on the roof to do repairs as needed.

I would rethink using the existing equipment. My intermediate step was to do exactly that. I very quickly learned that was not an adequate system for being off grid aka boon docking. I scrapped all the original and upgraded equipment and started over. The fact you have 6g wire there already is a bonus. Set your panels up in a combined series and parallel and just watch your total amps to not exceed 6g wire current limits.

WRT batteries, for the house batteries, just go to LFP. Sell the FLA batteries on craig's list.

The 2,000w inverter will struggle with things like a microwave or coffee maker. It definitely won't run an air conditioner. Start thinking about things like a multiplus II 2x 120v or a pair of them paralleled together. I have one in my 50a 5th wheel, and we do have to manage our energy usage, but I can even run air conditioning with it, limited by my battery capacity. I also have completely abandoned my onboard charger. In fact while in full hookup, I let the batteries and solar run 12v systems, and campground plug to run 120v systems. I've had to use my small generator twice in the last 12 months, and once was when I needed to run the air conditioner over night.

 

[Capt Tango]

I have a 3kw Magnum inverter and it is a must to fire up our 850 watt microwave many RV microwaves are more demanding. I strongly suggest replacing the 2kw Magnum inverter and the system with.
Magnum Energy 3kw 12V Inverter/charger 125 Amp MSH-3012RV
Magnum Energy Remote Control for All Magnum Inverters ME-RC50-L the "L" stands for Lithium compatible.
Magnum Energy Automatic Generator Start Module Network Version ME-AGS-N
Magnum Energy Battery Monitor Kit with Shunt ME-BMK-NS

Also consider a Lithium Battery Isolation Manager so you don't have an alternator melt down. I suggest pulling your existing battery maintainer, battery isolator and battery booster. and replace with a Progressive Circuits Li BIM 225.

 

[richard cabesa]

As to panels, don’t just buy the biggest you see. Play a game of Tetris on your roof and you may find you can get more watts by using more small panels than large panels.

My 2000 watt xanttex inverter runs my 1800 watt induction cooktop just fine. Micro too just not at the same time. Only thing it won’t run is the AC