Absorption Fridge Running on Solar/Battery/Inverter System
Absorption or Compressor Fridge, Which One?
I have installed a fairly large solar electric system in my truck camper. It has 675 watts of solar panels on the roof. 400-amp hours of lithium iron batteries. I also like having the fall back of a 30-amp DC to DC charger from the alternator. Normally I run my batteries down to about 85% full through the course of an evening till bedtime. The electrical system is generally fully recharged by 10 to 11 AM. The rest of the days solar power generation has nowhere to go and be used so is wasted. I decided to try running my absorption fridge off the electrical system to see how well it would handle the load. I have a 600-watt pure sinewave inverter which can easily handle the 312 watts the fridge heating element takes. I ran the fridge for 5 hours at night till around 11 when the batteries hit 72% charge. The next morning, I reconnected the fridge at 6:30 AM and ran it all day into the evening. The solar peak output for the day was 472 watts though I have seen it register as high as 745 watts, 70 watts more than the rated output of my 4 solar panels. The fridge runs intermittently through the day as the thermostat in the fridge cycles the system on and off to keep temperature. The fridge and electrical system worked fine all day and come about 4 PM, the batteries were fully recharged from 72% and the fridge had been operating normally all day. When the fridge would kick on, it wants 312 watts or about 24 amps at 13.2 volts from the inverter, batteries, and solar panels. Typically, the Victron 150/70 MPPT charge controller reported around 30+ amps output on the battery side. The battery BMS reported 15+ amps each battery coming in and when the fridge kicked on, the current would divert from charging the batteries to running the inverter and fridge. The BMS would show the battery charge current in, drop from 15+ down to 3+ amps each, the surplus solar energy is more than needed to run the fridge, so it still keeps charging the batteries.
This method works well in spring, summer, fall during good sunny days. Powering the fridge using the solar electric system can save me I suppose around 8 5-gallon propane tanks a year or 250 to 300 dollars. That's money that can go towards fuel for a trip or two. I should also be able to use other electric items like an Instapot to reduce cooking with propane though I would need a larger inverter.
The solar electric system produces a large surplus of energy that would otherwise go unused. Using it to power the absorption fridge makes perfect sense to me as the fridge is a big propane user since it is on 24/7/365 for me, always being stocked ready to go. Other people have used secondary loads as well such as the water heater, trolling motor batteries, EBIKE batteries and whatever else you can imagine.
Ultimately, this is sort of a comparison between the practicality of a compressor fridge versus an absorption fridge. A compressor fridge does use about 1/3rd the power of an equivalent size absorption fridge. But what of the finer details. The fridges are not on all day, they cycle on and off. A compressor fridge makes noise that can be annoying to some. There are people who have removed them due to noise issues. As for performance, I have no issue with my new Amish Built improved efficiency cooling unit which I installed a year and a half ago, still working perfectly and best of all, silently. For me, I have the capacity to run the absorption fridge. It would be foolish of me to not run the fridge off the electric system and let that power go to waste. My solar system is capable of producing 4 KWH a day. I get the solar power whether I want it or not. If I use it to run the absorption fridge, I get to keep the propane in return. There is no return with the compressor fridge. It either uses the power or not.
In this video, I'll give you the visual presentation of this setup. The second half of the video is going to be showing all the screen shots of the GUI's from the MPPT and BMS. I'll be reading and explaining the information as the reports progress through the day till the end of the video. Probably a little and dry and not exciting enough to hold most peoples attention, but if you like this topic and are wondering about whether to go Absorption or Compressor fridge, this should be an informative video for you.
Enjoy!
I have installed a fairly large solar electric system in my truck camper. It has 675 watts of solar panels on the roof. 400-amp hours of lithium iron batteries. I also like having the fall back of a 30-amp DC to DC charger from the alternator. Normally I run my batteries down to about 85% full through the course of an evening till bedtime. The electrical system is generally fully recharged by 10 to 11 AM. The rest of the days solar power generation has nowhere to go and be used so is wasted. I decided to try running my absorption fridge off the electrical system to see how well it would handle the load. I have a 600-watt pure sinewave inverter which can easily handle the 312 watts the fridge heating element takes. I ran the fridge for 5 hours at night till around 11 when the batteries hit 72% charge. The next morning, I reconnected the fridge at 6:30 AM and ran it all day into the evening. The solar peak output for the day was 472 watts though I have seen it register as high as 745 watts, 70 watts more than the rated output of my 4 solar panels. The fridge runs intermittently through the day as the thermostat in the fridge cycles the system on and off to keep temperature. The fridge and electrical system worked fine all day and come about 4 PM, the batteries were fully recharged from 72% and the fridge had been operating normally all day. When the fridge would kick on, it wants 312 watts or about 24 amps at 13.2 volts from the inverter, batteries, and solar panels. Typically, the Victron 150/70 MPPT charge controller reported around 30+ amps output on the battery side. The battery BMS reported 15+ amps each battery coming in and when the fridge kicked on, the current would divert from charging the batteries to running the inverter and fridge. The BMS would show the battery charge current in, drop from 15+ down to 3+ amps each, the surplus solar energy is more than needed to run the fridge, so it still keeps charging the batteries.
This method works well in spring, summer, fall during good sunny days. Powering the fridge using the solar electric system can save me I suppose around 8 5-gallon propane tanks a year or 250 to 300 dollars. That's money that can go towards fuel for a trip or two. I should also be able to use other electric items like an Instapot to reduce cooking with propane though I would need a larger inverter.
The solar electric system produces a large surplus of energy that would otherwise go unused. Using it to power the absorption fridge makes perfect sense to me as the fridge is a big propane user since it is on 24/7/365 for me, always being stocked ready to go. Other people have used secondary loads as well such as the water heater, trolling motor batteries, EBIKE batteries and whatever else you can imagine.
Ultimately, this is sort of a comparison between the practicality of a compressor fridge versus an absorption fridge. A compressor fridge does use about 1/3rd the power of an equivalent size absorption fridge. But what of the finer details. The fridges are not on all day, they cycle on and off. A compressor fridge makes noise that can be annoying to some. There are people who have removed them due to noise issues. As for performance, I have no issue with my new Amish Built improved efficiency cooling unit which I installed a year and a half ago, still working perfectly and best of all, silently. For me, I have the capacity to run the absorption fridge. It would be foolish of me to not run the fridge off the electric system and let that power go to waste. My solar system is capable of producing 4 KWH a day. I get the solar power whether I want it or not. If I use it to run the absorption fridge, I get to keep the propane in return. There is no return with the compressor fridge. It either uses the power or not.
In this video, I'll give you the visual presentation of this setup. The second half of the video is going to be showing all the screen shots of the GUI's from the MPPT and BMS. I'll be reading and explaining the information as the reports progress through the day till the end of the video. Probably a little and dry and not exciting enough to hold most peoples attention, but if you like this topic and are wondering about whether to go Absorption or Compressor fridge, this should be an informative video for you.
Enjoy!
