Compete noob post - where do i start?

kb taco

New Member
Joined
Dec 6, 2021
Messages
2
Good Morning. I've gone through the videos and have Will's Mobile Solar Power book, and have a few basic questions regarding fuses. I want to make sure they are in the correct location and correct size. Max energy draw will be 20A (LED lights, small pump for mattress, iPhones). My setup I'm building is a 100W Renogy Flexible panel that will be mounted to camper roof, connected to a Renogy 20A Rover MPPT charge Controller, connected to a 105AH AGM Battery. The Battery will be connected to a Fuse Block with a Disconnect Switch (to turn off power to the Fuse Block) between the Battery and Fuse Block. The attached drawing shows how the setup will be. My questions on fuses,
1) I believe I should have a Bolt-On Fuse attached to the Battery between the Charge Controller and Battery; am I correct? What size should I have here?
2) I believe I should have another fuse to the Charge Controller that will be 25-30A (I plan on a 30A ANL fuse heresolar setup.jpg; am I correct? If not, what should I have here?
3) Do I need a fuse between the Battery and Disconnect Switch, or is that the bolt on fuse to the battery?

Any other suggestions would be very helpful.
 

MichaelK

Photon Sorcerer
Joined
Mar 21, 2020
Messages
2,124
20A is a lot of current to be pulling out of just one 105Ah battery, and 100W is very small for replacing that amount of power. Can you itemize all your loads in watts for a more accurate description? Are these all going to be 12VDC loads only?

What I would recommend is scaling up somewhat to two 6V golf-cart batteries in the 210-250Ah range, being charged by two large 60-cell panels wired in series, say 240-250W each for a total of 450-500W. Laying flat on your roof, one little 100W panel is going to put out very little power, I'd estimate it's likely to be only in the range of 60W at it's very best. I'd replace the 20A controller with a 40A version.
 

kb taco

New Member
Joined
Dec 6, 2021
Messages
2
I appreciate your input, thank you. The solar panel will be charging all day. I use the truck and camper on the weekends only, so I figure it will just trickle charge the battery.

All 12vDC. Itemized list below as it stands now:
  • Lower LED Lights: 18w max power. lower to 80% 11w.
  • Upper LED Lights: 10w max power
  • 3 iPhones: 15w (very rare there will be 3; I figure two 99% of the time)
  • Air pump: 60w max power. Use only to inflate and deflate a mattress
Total: 103w ~9A.

In reality I don't have a whole lot of draw. I can't figure out the fusing.

Thank you.
 

rmaddy

Full-time Solar-powered Trailer Life
Joined
Nov 16, 2019
Messages
3,395
Location
USA
Work out your total watt hour per day usage. For example, how many hours per day will you have your lower LED lights on? If you used them for 2.5 hour per day at 18W then that would be 45Wh/day. Work that out for all of your loads and get a grand total of watt hours per day.

Your 12V 105Ah battery has a total energy capacity of 1260Wh but you can only use 50% so you have 630Wh.

A flexible 100W panel mounted flat on a roof is going to get you maybe 75-80W midday in the summer. You might get 5 good hours in a day so you might get up to 400Wh out of the panel on a good day. Much less on cloudy days or the Spring or Fall.
 
Joined
Nov 30, 2019
Messages
12,142
I took the liberty of re-factoring your setup.
Use 6 awg between the battery and the fuse_block
Use a quality 100 amp breaker between the battery and the fuse_block
Everything else connects to the downstream side of the fuse_block
Code:
legend {
    {} { funcitonal block }
    pos { positive }
    neg { negative }
    NNN|nnn| { fused position on block where NNN = wire guage and nnn = fuse ampacity
    NNN|UUU| { un-fused position on block where NNN = wire guage
    <-> { bi-directional current flow }
    -> { uni-directional current flow }
    <- { uni-directional current flow }
    dpst_breaker { double pole single throw breaker }
}
fuse_block {
    upstream {
        pos<->100A_breaker<->battery.pos
        neg<->battery.neg
    }
    downstream {
        pos {
            010|030|<-solar_charge_controller<-dpst_breaker<-panel.pos
            ???|???|->leds
            ???|???|->air_pump
            ???|???|->iphone
        }
        neg {
            010|UUU|->solar_charge_controller->dpst_breaker->panel.neg
            ???|UUU|<-leds
            ???|UUU|<-air_pump
            ???|UUU|<-iphone
        }
    }
}
 
Last edited:

MichaelK

Photon Sorcerer
Joined
Mar 21, 2020
Messages
2,124
I appreciate your input, thank you. The solar panel will be charging all day. I use the truck and camper on the weekends only, so I figure it will just trickle charge the battery.
That panel would be marginal for that size battery if oriented directly at the sun. Laying flat, you'll get next to nothing in the morning and the afternoon, and a few watts between 10am and 2pm. Just expect it not to keep up.
 
Top