I need Help

[Danyenah10]

HI everybody , I am very new to this , I was planning on installing a solar system on the roof of a Mercedes Sprinter that would be capable of running a roof top air conditioner , I am toying with the idea of the following 3x350 watt 12 volt solar panels with 30amp fuses and blocking diodes then into 3 to 1 branch connectors then into a 60 amp mppt solar controller then into 2x 300 amp lithium batteries , I know it sound heavy but roof top air cons use a lot of amps …any suggestions on size of cable from the 3 in 1 connectors to solar controller .
any suggestions or advice would be greatly appreciated.
many thanks Mike

 

[42OhmsPA]

Start with a load calculations and a power audit... V x A = W
You'll quickly realize you're going to want a lot more panel and battery.

Oh and welcome to the forum Mike.

 

[Danyenah10]

Thanks very much …I will to some calculations and update.
cheers

 

[Shinzul]

For comparison, we have a pop-up camper with a rooftop AC unit that pulls about 1200 watts.

 

[chrisski]

AC on rooftop solar is a tall order.

My rooftop has 1650 watts of panels and my panels have topped out at 1100 watts production in April with the sun high in the sky, and I only get close to that for a couple hours before and a couple hours after 12 pm.

My AC draws 1470 watts from the inverter, but I need 1650 watts from the battery to run it to cover both the inverter and conversion losses.

To cover the excess needed to run the AC, I put out 900 watts of panels on the ground. That actulally puts out 900 watts. With that, I can comfortably run the AC off solar and watch TV with lights on, but very little extra for battery charging.

This weekend, I‘m actually side mounting 300 watts of panels give A couple hundred watts of charging power.

 

[Supervstech]

HI everybody , I am very new to this , I was planning on installing a solar system on the roof of a Mercedes Sprinter that would be capable of running a roof top air conditioner , I am toying with the idea of the following 3x350 watt 12 volt solar panels with 30amp fuses and blocking diodes then into 3 to 1 branch connectors then into a 60 amp mppt solar controller then into 2x 300 amp lithium batteries , I know it sound heavy but roof top air cons use a lot of amps …any suggestions on size of cable from the 3 in 1 connectors to solar controller .
any suggestions or advice would be greatly appreciated.
many thanks Mike

You will be hard pressed to find 350W 12V solar panels. And you wouldn’t want to.
High wattage panels are frequently 37V or higher.
If you run parallel 12V panels your wattage would be around 90… you would need #2 copper to handle the minimum of that load. Sized for maximum wattage delivery, likely would require 1/0 copper… however, if you allow high voltage series run, the voltage would be over 90, and amperage on the cable would be under 12A… so, #10 would be plenty big enough.
Feed this into a quality MPPT controller, and it feeds the high amperage to the short distance of the battery bank. Far less length is far less loss…

 

[Supervstech]

HI everybody , I am very new to this , I was planning on installing a solar system on the roof of a Mercedes Sprinter that would be capable of running a roof top air conditioner , I am toying with the idea of the following 3x350 watt 12 volt solar panels with 30amp fuses and blocking diodes then into 3 to 1 branch connectors then into a 60 amp mppt solar controller then into 2x 300 amp lithium batteries , I know it sound heavy but roof top air cons use a lot of amps …any suggestions on size of cable from the 3 in 1 connectors to solar controller .
any suggestions or advice would be greatly appreciated.
many thanks Mike

How long is your van? Keep in mind, unless you are building the rack high enough to go over the rooftop ac, the ac unit will not only limit how much solar you can fit up there, it will cause shadows that limit solar production.

 

[chrisski]

After having watched one of Will’s videos that says “AC builds require you filling your roof up with panels and then putting as many on the ground,” and having built an RV build to run a single AC unit, I agree with that.

 

[Gordonthefreeman]

I'd make sure your sprinter van is well insulated, then find a 24vdc rooftop air unit. The becool one I found with a quick Google search uses 500/1000w, max output of 12000btu. A couple panels and the unit running at low power should keep the batteries charged and the sprinter bearable if not cool