Ok, I have done research and read what I could find. I am pretty sure the installation I have down, but I just want to make sure I am barking up the right tree on certain aspects of the build.I recently removed a solar system from my home I just sold to re-install on my new home. Since the newer home is going to be smaller I thought about keeping two of the panels to install on the 5er. They are Sharp ND-208U1F.What I am trying to understand is what size/type controller to go with. I guess I should preface I am trying to keep the cost down. I figured since I already have the panels I would try solar on my RV. I don't necessarily "boondock", but when we take the TH out it is usually where there is no shore power. So I would like to not use the generator to charge my batteries.If my two panels produce 416 watts then Ohm's law says that is 35 amps with a 12 volt system. Correct? Therefore I need to go with a 40+ amp controller? What options of controller do I have? I see, Morning Star, Blue Sky, Outback etc. Is the price difference between the MPPT and the PWM worth it for my application? There seems to be a slew of controllers out there, but what is quality and what is junk?My head is swimming with all that I have been reading and I guess all I need is just some real life experience opinions.

Those are nominal "24 volt" panels. You will need a 40Amp MPPT controller to take the 24 volt input to 12 volts output to your battery.Be prepared for a lot of opinions as to "best".Doug

MPPT controller will be needed or else translate the battery in the RV to 24 volts. I'd go MPPT and 125% of the input wattage for sizing the controller (i.e. able to do 500 watts of input). It should be an excellent system when all is said and done.I'd choose a controller that has battery voltage sense wires, and a temperature compensation probe on the battery.I'd research til I found the best price for a true MPPT controller that met my needs.

30 amp Morningstar should serve you well. Kill it with a 45 if you must.http://www.morningstarcorp.com/products/tristar-mppt/

smkettner wrote:30 amp Morningstar should serve you well. Kill it with a 45 if you must.http://www.morningstarcorp.com/products/tristar-mppt/There is no must about it. This is why I posted the thread. I am looking for advice.I assumed if my amperage the panels were producing is over 35 amps then a 30 amp controller would not work.How is it you suggest a 30 amp? Also, the controller is good for 400 watts, but my system is 416. Am I am missing something here?

36v panels you need an mppt controller to use for charging 12v batterieseven with mppt you will never see more than 29.5a sustained output, most likely lessa 30amp mppt controller will do the job, just make sure it is a real mppt and not one of the $30 fakes

Solar Guidance | Good Sam Community

30 Replies

Calkidd
Explorer
Sep 04, 2015
Thanks for all the information. This is making it much easier.

Another question: I noticed that both Blue Sky and Morningstar have a remote interface for their respective controllers. Is this similar to the Bogart monitoring system?
JiminDenver
Explorer II
Sep 04, 2015
30 amp MPPT will be fine with those two.
2oldman
Explorer II
Sep 04, 2015
Calkidd wrote:
Also, the controller is good for 400 watts, but my system is 416. Am I am missing something here?
You will never actually see 416 watts. Maybe 320 at best.
time2roll
Nomad
Sep 04, 2015
Calkidd wrote:
smkettner wrote:
30 amp Morningstar should serve you well. Kill it with a 45 if you must.

http://www.morningstarcorp.com/products/tristar-mppt/

There is no must about it. This is why I posted the thread. I am looking for advice.

I assumed if my amperage the panels were producing is over 35 amps then a 30 amp controller would not work.

How is it you suggest a 30 amp? Also, the controller is good for 400 watts, but my system is 416. Am I am missing something here?

16 watts does not matter enough to care.
Click the link and find the 'string selection tool'
Enter your panels and the mppt 30 and you are GREEN as in good to go for series or parallel.
More_To_See
Explorer
Sep 04, 2015
A Schneider/Xantrex C40 charge controller handles up to 125 volts open circuit. Thus you could put your panels in series. There are adjustments for both bulk and float. And it has an equalization mode. About $115. The optional battery temp sensor is about $20. A remote panel sets you back about $90 but that could be added later.
MrWizard
Moderator
Sep 04, 2015
36v panels you need an mppt controller to use for charging 12v batteries

even with mppt you will never see more than 29.5a sustained output, most likely less

a 30amp mppt controller will do the job, just make sure it is a real mppt and not one of the $30 fakes
Calkidd
Explorer
Sep 04, 2015
smkettner wrote:
30 amp Morningstar should serve you well. Kill it with a 45 if you must.

http://www.morningstarcorp.com/products/tristar-mppt/

There is no must about it. This is why I posted the thread. I am looking for advice.

I assumed if my amperage the panels were producing is over 35 amps then a 30 amp controller would not work.

How is it you suggest a 30 amp? Also, the controller is good for 400 watts, but my system is 416. Am I am missing something here?
time2roll
Nomad
Sep 04, 2015
30 amp Morningstar should serve you well. Kill it with a 45 if you must.

http://www.morningstarcorp.com/products/tristar-mppt/
pianotuna
Nomad III
Sep 04, 2015
MPPT controller will be needed or else translate the battery in the RV to 24 volts. I'd go MPPT and 125% of the input wattage for sizing the controller (i.e. able to do 500 watts of input). It should be an excellent system when all is said and done.

I'd choose a controller that has battery voltage sense wires, and a temperature compensation probe on the battery.

I'd research til I found the best price for a true MPPT controller that met my needs.
doughere
Explorer
Sep 04, 2015
Those are nominal "24 volt" panels. You will need a 40Amp MPPT controller to take the 24 volt input to 12 volts output to your battery.

Be prepared for a lot of opinions as to "best".

Doug

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