I took delivery of a new 2015 Grandby Front Dinette Model about a month ago.
I was ready to setup the 12 volts system to my camper and here is how I planned it out.
Hopefully this helps some of you who are looking to do the same thing.
My last setup had a wonderful battery/solar/monitor setup and I wanted to make this one similar in performance.
Here were the last specs:
200 amp hours of 2x12 volt AGMS
340 Watts of Solar glued to the roof (never came off - see below)
1 trimetric 2030 monitor
210 amp hours of 2x6 volt AGMs
250 Watts of Solar from rigid panel
1 trimetric 2030 monitor
When sizing a battery/solar/monitor setup you need to ask a few questions:
1- How much power am I going to use in an average day?
2- Do I have enough battery power to make it at least 1-2 days without any power coming in?
3- Is my solar enough to charge my batteries and run my system during the day time hours?
How much power an I going to use in an average day?
From my last FWC Hawk, I used an average of 40-60 amps per day with most of that power coming from my 110 litter 2 way fridge and my furnace. See this for more information:
My new Grandby has the same fridge and furnace. It does have a few more LED lights but those are pretty minimal power users.
I use an average of 50 amps per day.
Do I have enough battery power to make it at least 1-2 days without any power coming in?
I have calculated that I need about 50 amps per day (maybe less) of energy to run my system without an issues.
2 days = 100 amps
I can safely discharge about 50-60% of my battery bank without damaging it.
So I would need at least 200 amp hours of battery power.
Is my solar enough to charge my batteries and run my system during the day time hours?
During the day time hours when it is warmer, my fridge cycles on more often. I use some lights and occasionally charge items during the day.
With those needs, I could be using up to 5-6 amps at a time during the day.
My solar would need to overcome that plus recharge my batteries.
In Idaho I would get 5 solar hours a day.
You can figure out your solar hours from here:
50 amp hours to recover divided by 5 solar hours = 10 amps/solar hour
To recharge my system I would need to generate at least 10 amps per solar hour and 15 amps would be ideal.
amps x volts = Watts
10 amps x 14 volts of charge = 140 watts (adequate)
15 amps x 14 volts of charge = 200 watts (ideal)
There is some voltage loss from the controller, wiring, etc.. There is also some cloudy days, parking in the shade, etc... to overcome.
So I went with 250 watt panel.
But I do think 150-200 watts would have worked ok too as long as I was careful.
I originally had 270 watts of flexible panels, but my glue down job was subpar and the panels were not well constructed for this type of use. And they went flying off my camper during the first trip.
So now, I have a heavy, big, and rigid panel.
It works great.
Here are some pictures of my handy (sort of) work.
New 6 Volts vs older 12 volts
Trimetric Wiring Setup