What I've learned about solar energy and fridges

[Sea Diamond]

Thought I'd pass along what I've learnt about one of our most important items for our trips. So...we have a lot of gadgets that need charging besides our fridge. And it's been a learning exercise over the last couple of years.

Anyways...forget the learning curve...this is what we currently have... 2 x 50w panels mounted to the front removable roof sections...wired in parallel (surprised more Jeep owners don't do this). I also have 2 x 100w loose panels wired in series that are disconnected while driving and stored above the interior rollbars.

I use a MPPT solar controller...these are more efficient than a PWM unit. It's supports a 100ah Lithium battery which I've killed once but was able to bring it back.

In regards to our fridge (30L) a cover is a necessity and if you have mess over the vents...cut that out (it only restricts the air flow. I also keep the fridge outside while we are parked otherwise the thing just cycles too much. And I manage the temperature in small increments not to put too much load on the system (part of my early pro

 

[Sea Diamond]

Seems I lost some of my text...

So the small increments for temp was reducing the sys. load (something I learned when I killed my battery). We are currently just over a month on this trip and haven't plugged in nor do we plan to. Hot cloudy days and shade are my biggest hurdles.

Anyways...would really appreciate input/advice as I continue to fine tune my system.

 

[grubworm]

sounds good. i have a 50w panel permanently mounted to my camper shell feeding a 35ah battery with a mppt controller and that works great for the small loads i run in the shell and my camp trailers have 100w feeding 100ah battery and the bigger camper has 200w feeding a 200ah battery. i use agm batteries, so dont have the efficiency or storage of your lithium. my panels are permanent on top of the campers, so they charge all day while im driving, so if its cloudy, i still end up with a decent charge since i can use the panels while driving.

sounds like you have a really good set up. what happened to the lithium battery when you say you killed it? you discharged it too far? i dont know much about lithium. i have of lot of milwaukee power tools that run off lithium batteries and i always discharge them as far as they will go and recharge them. some of those batteries have seen 1000 or more recharge cycles and still going strong. i know they have a lot of built in circuitry in the battery, so i guess lithium needs good charge control and discharge control.

for your set up, i really cant see any improvements to make..

 

[Tundracamper]

… We are currently just over a month on this trip and haven't plugged in nor do we plan to.

Do you charge on the road? If so, that 12V comes from a generator, which is the same a plugging in to 120V.

 

[Sea Diamond]

Hi guys...thanks for the feedback and my internet seems good this morning :-)

Ya...when I say "killed" I mean drained my battery pass the point where my controller would kick in and start charging. That's when I bought an insulated cover and a plug in AC charger. The cover has made a big difference and like I mentioned above I removed the mesh that covered the fridge vents.

How I wired the panels was very important...in combination (series and parallel). Wiring the 50's in parallel essentially make it a 100w panel by keeping the voltage the same and doubling amperage output. Then when I wire the string in series the voltage adds together (good for cloudy days and shady campsites) while my amperage is added together.

I do have an inverter installed in the vehicle coupled to its battery but we seldom use this. Usually I disconnect the battery once we make camp...I've drained the battery once and had to use the solar system to recharge otherwise we would've been totally screwed...haha

Anyways...the are no government campsites over here so most of our camps are remote and unsupported. We do make use of Park parking lots to get off the ground and replenish our supplies from nearby towns or cities. My wife just returned from town with a styrofoam container filled with salmon (bought online)...so now you know how important our fridge is ;-)

 

[Sea Diamond]

I guess I didn't address Tundracamper's question. Our solar system is separate from the vehicle and our camps are seldom a one day affair...typically more like a week at a time. This makes the solar system efficiency way more critical. The converter receptacle is always buried and one of my tasks is to relocate to the rear of vehicle one day. When we do travel the solar system is being fed by the 2 x 50w panels mounted on the roof.

Anyways...this forum has been a great resource and catalyst for inspiration. If I can give back in some way to help inspire or assist those who might make the same mistakes as I have....it's been a good day.

 

[El-Dracho]

Thank you for sharing your setup experience here in such detail. That's great because it helps other members.

I have a similar setup. The aux battery is completely independent of the rig and feeds fridge etc. The battery has 95Ah and is only charged by a 100W solar panel and MPPT controller. This works perfectly since about 12 years now. Just as a backup I have a charger for 230V permanently installed.

 

[HighVoltOverland]

I have a 135kwh battery and I still use my 12v battery from my old rig to power my fridge because it gives me peace of mind

 

[Ragman]

I will likely be looking at something early next year so your insight is much appreciated, everyone's is actually!

 

[Sea Diamond]

Thank you for sharing your setup experience here in such detail. That's great because it helps other members.

I have a similar setup. The aux battery is completely independent of the rig and feeds fridge etc. The battery has 95Ah and is only charged by a 100W solar panel and MPPT controller. This works perfectly since about 12 years now. Just as a backup I have a charger for 230V permanently installed.

Hey thanks for the kind words....

Question for ya...100w panel seems kinda small to support a fridge...who's fridge are you using and what size? We can get hit by bad weather while it's hot and a total of 300w of panels just gets me through. And that's with careful management. How do you manage it...any tricks to pass on?

This morning's camp...Shaanxi Province...some random mountain range.

 

[El-Dracho]

@Sea Diamond It is an Engel MT27F with 21 liters / 22 quarts volume. Cooling capacity down to minus 21 degrees Celsius / minus 6F. This has a power consumption of just 35 watts at 12V as the larger Engel fridges up to the 45 models also. Once at the desired cooling temperature, these compressor fridges rarely start (depending on ambient temperature) and then running for a short period only.

What is important that a fridge is always fully filled, the goods inside are accumulating the cold much more better than just air. Helpful can also be a so-called cold accumulator, which is available from some manufacturers or also as a universal accessory.

By the way, here is a lot of information and experience how much solar power is needed or useful:

How much solar

Thinking of changing my solar setup from roof mounted hard panels to hood mounted soft panel to help with MPG. Currently running 2x100 watt panel to a 100AH AGM battery with a Redarc controller. I have a ICECO 45L dual zone fridge, led lights and that’s it. Fridge uses about 10watts per hour, or...

www.overlandbound.com

Maybe also interesting for you.

My experience and approach in a nutshell:

• Make a list and write down how many watts your electrical devices consume and how long you use them per day. This way you can determine the required watt hours. This is the energy that you need to draw from and return to your battery during one (average) day.
• Now you need to know how long on average the sun shines at your travel location. Thus you can calculate how big the module should be in average.

 

[Sea Diamond]

heyyyy...this has been good and thanks for all the personal experiences. We've been hit by foul weather and my electricity making has taken a bit of a nose dive. This has reminded me of why I wire my panels in series...basically you are adding your voltage together while the amperage remains the same as your lowest rating. Some controllers drop out as voltage nears the battery's voltage.

Anyways...on a side note...authorities came to our camp last night and told us (and the nearby village of 20) to evacuate due to the threat of a landslide. The rain has now subsided and we've returned to find our gear untouched by Mother Nature's strength.

A pic of our camp...looks like glamping and it certainly feels like it. Awesome to come across something like this in bad weather...even if you have to bug out in the middle of the night.