RV Solar upgrade time again

[Isaac-1]

I currently have 4 100 watt Grape Solar panels (installed 9 years ago) a Renogy DCC-50S MPPT / DC-DC charger (installed 18 months ago), feeding a pair of Rebel brand 200AH 12V LiFePo4 batteries.

As chance would have it, I have recently acquired some lightly used LG Neon 305 watt panels (circa 4 years old, removed 2 years ago from a storm damaged installation), and I am looking at installing 4 of these on my motorhome, possibly 5 of them if I can shoe horn them into fitting. Specs are VOC 40.1, ISC 9.93, VMPP 32.5

This leads to the big question, how do I handle the odd size strings for MPPT controller if I can fit 5 panels?

If I go with only 4, I am assuming a 2x2 layout, and needing a circa 80A MPPT controller, I am not sure of what brand as money is a factor, and I have several other major projects (house remodeling) going on. Any suggestion on something cheaper than Victron, that is not junk, should I go Renogy since I have one of their products now, and will likely keep using it for the DC-DC charger feature, something under $400 would be great.

thanks for your thoughts and suggestions.

 

[rodrick]

Epever make some good mid level mppts just make sure you get the mt50 with it

 

[rodrick]

I currently have 4 100 watt Grape Solar panels (installed 9 years ago) a Renogy DCC-50S MPPT / DC-DC charger (installed 18 months ago), feeding a pair of Rebel brand 200AH 12V LiFePo4 batteries.

As chance would have it, I have recently acquired some lightly used LG Neon 305 watt panels (circa 4 years old, removed 2 years ago from a storm damaged installation), and I am looking at installing 4 of these on my motorhome, possibly 5 of them if I can shoe horn them into fitting. Specs are VOC 40.1, ISC 9.93, VMPP 32.5

This leads to the big question, how do I handle the odd size strings for MPPT controller if I can fit 5 panels?

If I go with only 4, I am assuming a 2x2 layout, and needing a circa 80A MPPT controller, I am not sure of what brand as money is a factor, and I have several other major projects (house remodeling) going on. Any suggestion on something cheaper than Victron, that is not junk, should I go Renogy since I have one of their products now, and will likely keep using it for the DC-DC charger feature, something under $400 would be great.

thanks for your thoughts and suggestions.

You might also think about 2 40 amp units vrs a 80 amp might be cheaper and you will have some redundancy

 

[SamDeleted]

Just to confirm it is a 12v system ?


You'd have to do the maths properly on a calculator, but I pretty sure a 150v max input mppt can take 3 of those LG panels series

https://www.amazon.com/SolarEpic-Charge-Controller-Temperature-Communication/dp/B07429RK43

So you could use 2 of these MPPTs in parallel to your batteries,

one with 2 panels in series, one with 3 panels in series

 

[Isaac-1]

Yes, it is 12V, I was not sure about peak cold voltage with 3 in a chain and if it would work, depending on the brand of controller

 

[SamDeleted]

Yes, it is 12V, I was not sure about peak cold voltage with 3 in a chain and if it would work, depending on the brand of controller

Solar Panel Maximum Voltage Calculator - Footprint Hero

Calculate the maximum open circuit voltage of your solar array. Find your max solar panel voltage to correctly size your solar charge controller.

footprinthero.com

This should help

 

[SamDeleted]

So long as the calculation comes out under the max solar input of the MPPT , you're good to go

 

[12VoltInstalls]

Being fairly short runs, I would wire them 5P. Parallel them on the roof. Run 6ga to SCC.
Alternatively get a 250V Victron but in your case i think 5P makes the most sense.