Newbie needs help

[ERNURTURNS]

Hi. I'm new here and new to setting up solar in general. I have almost completed my first sprinter van upfit and have installed solar to help with off grid camping. Alas I'm more of a hands on person where physically wiring is more up my alley than actually setting up parameters necessary for an efficient and effective build. I have a Renogy Rover 40a solar controller, 300watt of solar and 4 - 6v Trojan T-105 AGM batteries. I have attached links to information on the items I have and also posted a picture of my current settings on the solar controller. Can someone tell me if I am on the right path? If things are absolutely out to lunch or if I should tweak a few things? I've done a bit of reading and like everything there is mixed opinions on how things should be setup. Any info ANYONE can offer I'd be grateful and I am keen to learn more on setting this up.

Thank you!

Trojan Batteries
https://www.google.com/url?sa=t&sour...tXrPnXixaads4m
Renogy Rover 40a Solar Controller

https://www.renogy.com/content/Manual/RNG-CTRL-RVR203040.pdf

Solar Panels
https://www.renogy.com/content/files...0MB%20spec.pdf

[Mike90250]

what is your alternate charging source ? 300w of panels is not enough to keep that many batteries healthy.
Wiring panels: With only 3 panels, you have one choice - all in series. I hope the 3 panels in series, is less than the kill voltage of the charge controller. Wiring all 3 in parallel (18V) is not likely going to be able to activate the MPPT function of the controller. (page 26 of your manual, 20V needed)

[ERNURTURNS]

I do have a DC/DC charger as well as shore power with an inverter/charger as well. That being said I have seen the MPPT function coming on, on the screen of the controller. When you say 20v do you mean the output of the panels? According to the solar controller and my Bluetooth app Im seeing upwards of 55-60v from the panel. Is this not what I should see for voltage from panels in series?

Also can you explain what "kill voltage" is?

[Mike90250]

Panels in series, the voltage adds up. So for you to see 55-60V, your panels are in series.

The Kill voltage, is the voltage that is not to be exceeded at the PV input from the panels. Smaller controllers have lower ratings ( 45V, 75V, 100V), larger controllers are 150V - 600V

[ERNURTURNS]

My 40a controller says it's rated for 100v. So from what you've read. What have I done wrong or can do better to create an efficient system? Should I be cutting out a bank of 6v batteries?

[Mike90250]

I would add another PV panel, and wire 2 series, and then parallel the 2 series strings. That brings the PV voltage to 40ish volts, the controller will be more efficient.

Batteries. If you only use them lightly and you are able to achieve 1 hour of Float charge, you will be OK. If / when you do not achieve 1 hour of float, you need more PV or less drain on the batteries. Going to fewer batteries at this point, will not buy/save you anything

[ERNURTURNS]

I would add another PV panel, and wire 2 series, and then parallel the 2 series strings. That brings the PV voltage to 40ish volts, the controller will be more efficient.

Batteries. If you only use them lightly and you are able to achieve 1 hour of Float charge, you will be OK. If / when you do not achieve 1 hour of float, you need more PV or less drain on the batteries. Going to fewer batteries at this point, will not buy/save you anything

I definitely have more than an hour of float charge. It's reading float charge for most of the day. When I run mainly my Maxx air fan most of the day the readings hardly change. What does having at least an hour of float charge mean?

[Mike90250]

Lead acid batteries have a requirement for a set amount of recharge. The ABSORB phase only gets a battery into the 80-90% recharged zone. At least an hour of FLOAT is required to get the battery "topped off" to 100%. Lead acid cells sitting at less than 90% (some say 75%, some say 80%) begin to sulfate.

If you had been using your batteries heavily, you don't have enough solar (even 400w would still be marginal) to be able to completely recharge after a long winter night and short days. Take note of your float hours in the winter.

[ERNURTURNS]

Lead acid batteries have a requirement for a set amount of recharge. The ABSORB phase only gets a battery into the 80-90% recharged zone. At least an hour of FLOAT is required to get the battery "topped off" to 100%. Lead acid cells sitting at less than 90% (some say 75%, some say 80%) begin to sulfate.

If you had been using your batteries heavily, you don't have enough solar (even 400w would still be marginal) to be able to completely recharge after a long winter night and short days. Take note of your float hours in the winter.

Ah I see. As it sits now I only have a 60w alpicool fridge, a MaxxAir fan and some LED strip lighting. So I'm hoping to have enough for now. I guess I missed some math somewhere when I was doing my calculations. As for winter I want to eventually add a espar d2 heater, but I also have a stock supplemental battery under the hood (seperate starting batter) that I was reserving for that. A couple more questions if you don't mind.....

Looking at the settings on my renogy solar controller, do they look ok for what I have? To clarify, adding a 4th solar panel and running series parallel would/should be in my game plan?

Thanks again.

[Mike90250]

I think adding a 4th panel and wiring 2S2P is the way to go. unless you have a tilting mount on your array, harvesting 250w with 400w of panels flat on the roof, is going to be all you get, on a good day.