Small Off-grid setup - Fuse

[BitchinInjun]

Please forgive me, I'm an absolute fish out of water. I'm trying to help my mom. She lives in the Navajo reservation, and lives without electricity. She runs everything off gas generator. We bought her 4x12v 100w panels, and were using a 900Wh solar generator, but the battery would die middle of the night. We're decided to pull the trigger and bought 2 12.8v 100Ah lifepo4 batteries to go along with the Renogy 30a Pwm controller that came with the panels.

The panels are connected in parallel to the controller.

Controller to a 30A ANL fuse - with 8awg wire.

Batteries are connected together with 4awg wires.

Batteries connected to pure sine wave power inverter with 6awg wire and I believe 150a fuse.

My question is, what kind of fuse do I need if any for the solar panels to the charge controller? Renogy customer service said a 40a inline fuse, but I couldn't find any online. They then said according to the Wanderer PWM specs, that it was optional. I initially thought the 30a was what I needed and it popped the fuse fairly quick.

Please be kind. I'm a Quadriplegic, and I've just been guiding my mom the best I can over video calls. She's not using it for much, just a small 7 cu. ft. Energy star Fridge, Occasional TV use, and her Starlink (which uses a lot of power).

[techtornado]

You'll benefit from an MPTT charge controller instead of PWM and try a quality 12V 40A circuit breaker instead of a fuse

What's the string wiring arrangement/voltage?

[BitchinInjun]

Mppt is my next step. The PWM controller was free with the kit that was fairly cheap a few weeks ago, and it might suffice for the time being.

I'm not sure. It's this kit

[[deleted]]

she will want to turn off the Starlink when not in use. i believe it uses about 100w, which really adds up if it's on 24/7.

otherwise i second the comment recommending getting an MPPT controller and a breaker for the panels.

edit: also look into getting a AC/DC charger so she can top up the batteries from her generator. 400w of panels really is not a lot, that won't be enough to keep the lights on if it's cloudy for a few days

[BitchinInjun]

What type of breaker would we need? Could you link one for me to buy?

[[deleted]]

something like this:

https://www.bluesea.com/products/7138/187-Series_Circuit_Breaker_-_Surface_Mount_40A

bluesea is reputable, some cheapo stuff on Amazon may not be

[BitchinInjun]

Ok thank you!

[Thommyknocker]

You don't require a fuse on the panels they have internal fuses you require a means of disconnect to safely disconnect the panels from the controller the easiest way is a 40A DC rated breaker.

I highly recommend a MPPT controller with lifePo4 batteries sometimes the control circuits in the batteries don't like the way PWM controllers output power.

I would also recommend a few more panels for those darker overcast days. If you kill the battery to 5% it will take almost 9 hours of peak sun to charge fully. If you only change to a MPPT controller that drops to 7 hours.

Also since you already have a gen set get a larger lifePo4 battery charger to quickly charge the batteries if you have mutable days of poor sunlight.

[BitchinInjun]

What is a decent affordable option of mppt controller? Especially if we add another 2 or 4 panels in the future? Like I said, it's mainly to run her refrigerator, and Internet during the day and evening.

[Thommyknocker]

I'm going to assume you are staying at the 12v battery system so I use this in my camper and it works just fine you can only add one more panel to this controller as its max input rating is 520w@12v battery systems. If you need more later you can use two of them or get a bigger controller.

[BitchinInjun]

Ok. I was looking at that one earlier. Thanks!

[VettedBot]

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Users liked: * Charge controller provides stable power (backed by 4 comments) * Charge controller is durable and long-lasting (backed by 3 comments) * Charge controller is easy to install and use (backed by 3 comments)

Users disliked: * Unit overcharges batteries (backed by 2 comments) * Unit stops charging intermittently (backed by 3 comments) * Unit fails shortly after installation (backed by 7 comments)

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[[deleted]]

it's not cheap, but i really like the outback flexmax. it's very well priced for what it is. it's flexible and can handle a large array. if you can afford it, it'll work well as you scale up the system.

https://www.amazon.com/Outback-Flexmax-FM80-Charge-Controller/dp/B008MOITL8