Solar Build: Check my design please :)

Hey TW,

I'm looking to do a solar kit for my truck and have done my research, I have a diagram and gear selected. Hoping the electrical lads on the forum could point out an issues i might have or might have missed.

I installed a dual battery kit last year from offgrid engineering and have 2 odyssey AGM35 batteries installed to run my fridge from chilly moose.

Worked fantastic last summer camping and am looking to do longer trips and would like to have the security of being able to charge my battery via solar to keep it lasting long!

I've drawn up my solar diagram i plan to install behind my rear seats and my battery is located under the hood at the attached photos show.

Planning to buy the 100 Watt 12 volt solar starter kit with mppt charge controller from Renogy and their 500A battery monitor kit with shunt.

Already own the 1100W inverter.

Everything else ill source from local parts stores or Amazon if possible.

If my sketch isnt clear let me know! I tried my best.

Thanks in advance for the input!

 

Is your switch between the solar and controller a shutoff switch?

 

Yes it is, specifically a switch a voltage rating high enough for the solar panel max voltage (thats 600v) went with a 1000v switch as 600v doesnt seem like an option i can find easily.

 

Your setup is different but solar may be the same.

I had an EcoFlow and

$860 Dometic CFX3 35 Portable Refrigerator and Freezer - 36L - Powered by AC/DC or Solar Portable Refrigerator with WiFi/Bluetooth Temperature Control - Ideal Cooler for Car, RV, Camping and Home Use

Dometic CFX3 35. 100w flexible panel.
Wish I had more. Bigger fridge maybe freezer. Should have room.

more solar. It has room. Solid panel is more efficient and modular than flexible.

that is a lot of weight. JD has rear battery relocate box. I hope your fender or tub doesn’t rip from that. Probably doesn’t help front suspension and truck balance.

do you have 400w anytime harness?
Did you manage to fit that 1100w inverter into stock location under console to replace tiny stock one?

100w I was left chasing the sun, driving, idling, and wall charging. Not a lot. But I’d rather not have to at all. If the truck fits more than 100w than why go with the smallest 100w that would fit on a a Civic if not more than that.

I think most serious setups are more than 100w.

a larger fridge freezer sounds much better and draws more power.

 

Not a solar geek, but a little experience. Don’t know how long your runs are, but I suspect from your solar panel to mppt is 10 awg. I would use the same after the mppt to the buss bars. JMO
Otherwise it looks good.
Blue Sea’s website has a wiring size calculator and app that might help.
Now you’ve got me wanting to finish my camping setup!

 

Youre probaby right, runs are very short but best to stay with same wire size.

Thanks!

 

I'm happy with my current fridge and dont plan to change.

The battery setup has made no effect to suspension or driving but i have a full king 2.5" coilover setup with 700lb coils so that added weight isnt noticed.

i only have space for 1 panel on my roof with area i have left, i could jump to 200w panel later on in the future or add in the connection of a portable panel.

 

a 100w panel isnt going to power much, i think you will eventually drain your batteries with a fridge. A higher output alternator will work while driving. I can run a fridge off a bluetti and use the fold out panels. Just some info

 

I would have to disagree.

My fridge at peak pulls 45W, which its not full power all the time. My battery provides 708 watt hours, renogy states if their panel gets 6 hours of direct sunlight it can produce 600watt hours of power.

If we avg out my fridge at lets say 30w on average that means if i used my entire battery i could go for 24 hours without a charge. If i got even 300 watt hours out of the panel throughout a day that would give me roughly another half a day. And worst case the fridge will turn off if it gets below the set voltage. I guess i could got to a 200w panel to push the gap as they state 1000wh's from the 200w panel.

Also a higher output alternator would only help me if i move my truck, the idea is with solar i can stay put in the same spot for a couple of days without moving. This is primarily for summer camping adventures when its sunny for a large part of the day.

 

The two batterys with a high output alternator in my opinion will be a better setup. The renogy 100watt at peak sunlight maybe will provide a trickle charge to your battery but then your adding a lot variables that can fail when wired directly. When its hooooot outside your inverters fans will keep coming on and for me i wouldnt want to worry about it overheating inside the truck. but cool project, i have the renogy 3500 inverter at home with 1k of panels that i will eventually wire up one day

 

Renogy can say whatever they want. You don’t know the solar power until real life.

Solar is not 100% efficiency.
The sun is only directly overhead around noon and can be obscured by weather and trees. Nobody wants to bake in their truck.

Sun is out for a limited time and besides noon is at an angle and so is the truck.
If you stand outside and raise your hand like a kid with a question in class
Pointing up
That’s not where the sun is

and panels vary in pulling power from sideways angle. That’s why some have a ton of sphere shapes on them.

heat from weather, sun, baking the truck also reduces efficiency.

speaking from real life not paper and pen. Had 100w and about the smallest fridge there is. Was not enough. If that’s what you want cool.

if you’re camping then there is no Starbucks to walk into with a power station when the solar is not enough.

 

I’m on board with mostly everyone else’s opinion here that 100w of solar is not enough. You’ll see roughly 60-75% of that 100w due to their efficiency and that would be under optimal conditions. You might have to supplement with those ‘briefcase’ style portable panels you can throw on your windshield or ground when you are at camp.
Edit: forgot to mention you are running AGM batteries which don’t like to be discharged below 50% capacity so you are essentially running 1 battery now. If feasible, you could run a Li as a secondary and discharge that to 0% if you had to. BUT all this talk about power really has to do with your consumption. If just a fridge, you’ll probably be fine. With an inverter, it will depend if you keep it ‘powered on’ and if you use it for AC accessories. Just my opinion.

 

All good points. Having run solar for years and studied up on it more than a bit, I would not count on any more than 50% rated power. I'm running 350W rated right now and that seems to be a pretty good for running a fridge an misc other things in the NW. I was able to get away with half of that when operating in the Utah desert.

 

Do you need this all to be hardwired? I’d rig up a portable suitcase panel with a MPPT controller and SAE connectors. Put a SAE pigtail on your battery and run it out by headlight when needed. An angled panel that you can always have in the sun is much more efficient than a flat panel on your roof.

 

A little something from US Energy Admin regarding output with respect to pointing angle and time of day for a Los Angeles latitude. Note this for a 1000W panel, so read the y-axis as percent of panel rating. Couple things to notice are that peak output, at noon, for a tracking system is 70%, tilted south is 60% and flat is 52%-ish percent. So while pointing helps, it's only about a 20% increase over the non tracked output. The bigger point however is that if you were to integrate the output over the course of the day your average output looks like about 40% for a tilted panel and maybe 35% for a flat panel. Note that all of this assumes clear skies, not trees and a favorable latitude. When you get down to planning, unless you are a desert rat, maybe assuming 30% of the panel rating is a reasonable place to start.

So for a 100W panel assuming 30% for 6 hrs a day implies (rough numbers) 3 amps for 6 hrs or 18 A-hrs. From there you need to add up devices and estimated run times and convert those to amps-hrs. This will tell you both how big a battery you need in amp-hrs, and whether or not your solar system can keep up with the draw in "realistic" use. To be sure, if you are a desert rat you are in a far better situation and can reasonably double the output I describe for a typical 100 W panel for a day.