Off Grid Cabin - Will this work as intended?

[willh]

Just another data point for reference.

My parents cottage is in Western Newfoundland and we have 1200W of solar panels on the roof with 1100Ah of flooded lead acid cells at 12v. We have one of the unique 12/24v fridges. A 12V ~25A DC water pump, 12v DC lighting, and a 12v 1000w motormaster inverter running a TV, sat receiver, cell booster, laptop chargers, etc... We always have a surplus of power in the summer and fall. I don't have any data for the winters yet, I'm traveling there next week to check on the system. Everything is turned off except for the charge controller maintaining the batteries. In the summer we also have their motorhome plugged in. That is where we stayed when we visited for two weeks last summer.

They did run into some power shortages last spring before they bought the 12/24v fridge and they were powering the RV fridge in the motorhome. The RV fridge was consuming something like 3 to 5 kWh a day. The new fridge only 0.5kWh/day.

While I was there in July most days we produce in excess of 6kWh and the charge controller would be in float mode most of the day. In float mode it was only outputting around 200W. We had way more power than we needed. The TV and satellite receiver, cell booster, laptop chargers, etc... were running all day. I also had a fan running most nights.

They still have their Honda generator that dad mostly uses to power large tools. Stuff like an aircompressor and table saw. Smaller tools and battery chargers run fine off the inverter.

Exactly the real life type of experience/example I was looking for, thank you.

 

[Eastern Dave]

Since you are looking for real life examples here is mine. My system consists of 3 by 335 watt panels (1005 watts total). This is connected to 4 Rolls Surrette L16hc lead acid batteries wired in series to 24 volts. Total storage is in the area of 11 kw-hrs. The cabin it powers is a 736 sq ft 3 season cabin with lots of lights, (LED only), satellite tv, computer, charging etc which is wired conventionally for 120 v AC. When all lights are on draw is less than 1 amp. Total power consumption per day when there is calculated between 3-4 kw-hrs. Daily production in summer exceeds 5 kw-hrs on a sunny day, spring and fall 3-5 depending. Panels are south facing fixed at approx 32 degrees. For refrigeration started with 10 cu ft Danby from Costco ($400). Once my daughter had her annual get together decided it was too small and upgraded to an 18 cu ft Samsung with the digital inverter compressor from home depot ($895). Had close to the same annual power consumption rating as the Danby (364 kw-hr vs 297) for twice the space. Refrigeration ran from April to November without interruption with periodic cabin use (weekends, the odd week, long weekends etc, Always had ice). Did lose power in Late November after 8 consecutive days without sun. Generator used for power tools and other high draws. This was observed while at the same time using a defective breaker between the charge controller and the batteries which would shut down if over 700 watts was being sent to the batteries then reset itself. Cabin is located just outside of Halifax, Nova Scotia.

 

[Rednecktek]

I can only give you examples of how much weather affects systems in Monroe, WA:

System 1 - Garden Shed
-2x 100w Renology Poly panels in parallel, facing south @~45deg
HQST 20a MPPT controller
500w PSW inverter, 4w standby draw
WallyWorld 29DC 122Ah 12v FLA battery
40w LED ceiling fixture, average usage 2 hours every 6 months a few minute at a time when I'm home

In summer, battery is topped off by 9am. October - March it will run 4-5 weeks before the low battery alarm goes off on the inverter and we have to plug in the charger. It can't keep up with the standby draw of the inverter through winter. I can't keep up with the 100Wh/day.

System 2 - Driveway Lights
1x 100w Renology poly panel, facing West @~45deg on a
1x 20a PowMr PWM controller controlling the lights on the LOAD ports, shutoff @12.5v
1x 208w Mono panel, facing West @~25deg on a
1x 60a PowMr MPPT controller
36Ah AGM battery
1x Photocell @ 1w 24/7
2x 3w LED yard lights 14hr/7days
Total ~120Wh/day

In summer, the batteries top off somewhere around noon due to sun angle. Nov-March the system lasts 3-4 weeks before the battery needs to be "jump-started" with the Jackery. I can't keep up with 120Wh/day due to overcast.

 

[willh]

Since you are looking for real life examples here is mine. My system consists of 3 by 335 watt panels (1005 watts total). This is connected to 4 Rolls Surrette L16hc lead acid batteries wired in series to 24 volts. Total storage is in the area of 11 kw-hrs. The cabin it powers is a 736 sq ft 3 season cabin with lots of lights, (LED only), satellite tv, computer, charging etc which is wired conventionally for 120 v AC. When all lights are on draw is less than 1 amp. Total power consumption per day when there is calculated between 3-4 kw-hrs. Daily production in summer exceeds 5 kw-hrs on a sunny day, spring and fall 3-5 depending. Panels are south facing fixed at approx 32 degrees. For refrigeration started with 10 cu ft Danby from Costco ($400). Once my daughter had her annual get together decided it was too small and upgraded to an 18 cu ft Samsung with the digital inverter compressor from home depot ($895). Had close to the same annual power consumption rating as the Danby (364 kw-hr vs 297) for twice the space. Refrigeration ran from April to November without interruption with periodic cabin use (weekends, the odd week, long weekends etc, Always had ice). Did lose power in Late November after 8 consecutive days without sun. Generator used for power tools and other high draws. This was observed while at the same time using a defective breaker between the charge controller and the batteries which would shut down if over 700 watts was being sent to the batteries then reset itself. Cabin is located just outside of Halifax, Nova Scotia.

Great information thanks. What inverter are you using in your system? I just want to confirm that you leave the inverter/fridge running for the entire season, even while not there?

 

[willh]

I can only give you examples of how much weather affects systems in Monroe, WA:

System 1 - Garden Shed
-2x 100w Renology Poly panels in parallel, facing south @~45deg
HQST 20a MPPT controller
500w PSW inverter, 4w standby draw
WallyWorld 29DC 122Ah 12v FLA battery
40w LED ceiling fixture, average usage 2 hours every 6 months a few minute at a time when I'm home

In summer, battery is topped off by 9am. October - March it will run 4-5 weeks before the low battery alarm goes off on the inverter and we have to plug in the charger. It can't keep up with the standby draw of the inverter through winter. I can't keep up with the 100Wh/day.

System 2 - Driveway Lights
1x 100w Renology poly panel, facing West @~45deg on a
1x 20a PowMr PWM controller controlling the lights on the LOAD ports, shutoff @12.5v
1x 208w Mono panel, facing West @~25deg on a
1x 60a PowMr MPPT controller
36Ah AGM battery
1x Photocell @ 1w 24/7
2x 3w LED yard lights 14hr/7days
Total ~120Wh/day

In summer, the batteries top off somewhere around noon due to sun angle. Nov-March the system lasts 3-4 weeks before the battery needs to be "jump-started" with the Jackery. I can't keep up with 120Wh/day due to overcast.

Thanks for the info! Really good example of how much the change of seasons effects solar harvest. If our cabin starts being used outside of the 3 seasons the array would certainly need to be expanded.

 

[Eastern Dave]

Great information thanks. What inverter are you using in your system? I just want to confirm that you leave the inverter/fridge running for the entire season, even while not there?

I leave the inverter on 365 days per year. Gives a battery draw in the winter to keep charging cycles going. Fridge runs from April to close up in late November or early December. The inverter is a no name chinese model which is rated for 1500 watts, and a surge of 3000 watts. Plan to replace it with one I can plug the generator into so if we get a long stretch of cloudy weather I can use the Genny to charge the batteries to keep them above the 50% charge recommended. Shut off low voltage is set at 22 volts.

 

[Checkthisout]

How quickly do the 50 Watt fridges cool down from say 70?

 

[12VoltInstalls]

How quickly do the 50 Watt fridges cool down from say 70?

Is that an answerable question or purely subjective? Too many factors: empty, full, setting, density of contents…

 

[Checkthisout]

Is that an answerable question or purely subjective? Too many factors: empty, full, setting, density of contents…

Agreed.

In other words, intermittent use. I arrive at the cabin, crank it up and its room temp.

Put my partially cool stuff in there I got from the store on the way there.

When will my tepid beer be cold?

 

[Snowynorth]

I have not seen the numbers, but heard of a guy on solar in the lake area about 50kms from us. Who wanted to make his fridge more efficient. He first used a folded up quilt to wrap over top and sides. then tested consumption vs no wrap. Apparently it reduced power use enough to get his wife to sew something up with foam insulation that fits snuggly, top and 2 sides. I think there are others out there who have copied him.

 

[Snowynorth]

I suppose insulation could be rigged ups on the doors as well. I haven't done it but I'm interested, and will try it when my solar is in.

 

[12VoltInstalls]

Apparently it reduced power use enough to get his wife to sew something up with foam insulation that fits snuggly, top and 2 sides.

A lot of newer fridges bleed off their heat from the sides; mine’s like that. Nothing you can do for those models. I’m not aware of any decent sized but still small fridges (10-12CF) with the coils exposed on the rear but I could want one.

 

[Snowynorth]

Good to know 12voltinstalls. I never thought about that possibility.

 

[Snowynorth]

Are the newer fridges dissipating heat from the sides because of enclosed coils or possibly bottom coils? I'm going to try to track this guy down when the weather gets better. I "was" planning to use an older but very good 18 cu ft, that I have at home. I know it will use more power, but I was hoping to counter that by insulating. I'm over building solar somewhat, and fridge will get shut down for winter. I have a propane fridge set up for our little outdoor kitchen and have learned to hate it. The stove and clothes dryer are roughed in for both 120/240 and propane. We will be using propane, and 120v.

 

[Daddy Tanuki]

I run a 200 liter (7cuft) fridge and a 180 liter (6.3cuft) freezer at my cabin (I need some place for the beer and steaks) and my system works, but it ain't small! I have 38, 200 watt panels and a 30kw LiFePo4 bank. This guarantees no power outages when away, even with snow covering my panels for 4 days at a time.

I am currently looking for a fridge I can dismantle so that I can replace the coils with an outboard set of condenser coils and set them under the cabins crawl space along with a small fan. then double the insulation on the actual fridge by gluing some of the blue foam on all sides except the door and then recovering with more sheet metal.

 

[Checkthisout]

I run a 200 liter (7cuft) fridge and a 180 liter (6.3cuft) freezer at my cabin (I need some place for the beer and steaks) and my system works, but it ain't small! I have 38, 200 watt panels and a 30kw LiFePo4 bank. This guarantees no power outages when away, even with snow covering my panels for 4 days at a time.

I am currently looking for a fridge I can dismantle so that I can replace the coils with an outboard set of condenser coils and set them under the cabins crawl space along with a small fan. then double the insulation on the actual fridge by gluing some of the blue foam on all sides except the door and then recovering with more sheet metal.

Yeti fridge.

 

[Daddy Tanuki]

Yeti fridge.

you mean a cooler? no we are talking about a 8-12 cubic foot refrigerator with external condenser coils. I have two versions of the Engel 12 volt refrigerator and freezers, i use those in my camper. they are quite efficient but my cabin is wired for 120/240 split phase power from my inverters.

 

[Daddy Tanuki]

Are the newer fridges dissipating heat from the sides because of enclosed coils or possibly bottom coils? I'm going to try to track this guy down when the weather gets better. I "was" planning to use an older but very good 18 cu ft, that I have at home. I know it will use more power, but I was hoping to counter that by insulating. I'm over building solar somewhat, and fridge will get shut down for winter. I have a propane fridge set up for our little outdoor kitchen and have learned to hate it. The stove and clothes dryer are roughed in for both 120/240 and propane. We will be using propane, and 120v.

find a friend who is skilled at AC/R and either have him remove the current ocils if that is possible, or make you a new set of coils. Cover the sides, back and top with the XPS insulation then reattach the coils outside of the insulation. if he is really good have him look at other types of gas when he re-gas's, some are more efficient that others. depending upon state changeling gas may not necessarily legal. Other things such as brazing the new condenser to a large aluminum plate or heat sink with possibly a small efficient fan can work wonders as well.

 

[Snowynorth]

find a friend who is skilled at AC/R and either have him remove the current ocils if that is possible, or make you a new set of coils. Cover the sides, back and top with the XPS insulation then reattach the coils outside of the insulation. if he is really good have him look at other types of gas when he re-gas's, some are more efficient that others. depending upon state changeling gas may not necessarily legal. Other things such as brazing the new condenser to a large aluminum plate or heat sink with possibly a small efficient fan can work wonders as well.

If the coils are at the bottom, would a couple of small fans work to dissipate the heat enough to allow extra insulation top and sides? Now I'm really curious about this other guy, and how well his extra insulation worked, what he has for a fridge, and if it actually did work.

 

[Snowynorth]

I'm sorry I meant exposed on the back.