Solar panel and fridge

[thriftydutch]

Okay here goes. I have a 12v-120v fridge. It is a Norcold DE 704D model. What I want to know is how much solar do I need to run this fridge. Ask any question you want about the fridge and I will try to give that information. I have 2 12volt house batteries.
I am not concerned about winter time. Just spring, summer and fall when the sun is higher in the sky.
Please leave this in the class B section.

[crosscheck]

Reflex 439,
I agree with you completely. A generator is far more effective for your style of camping.
Dave

[Reflex439]

I agree with you completely. More solar and battery capacity means less generator run time. And reducing electrical loads (LEDs, efficient appliances, etc) and enough solar/batteries you can eliminate generators. But only to a point.

I guess put simply, the point I was trying make was to rely 100% on solar a few things need to happen, and most RV’s are not setup well to make this work (lack of roof real estate for enough panels, storage space for batteries, etc) under anything but very good circumstances.

1. You need sunny weather with minimal disruptions
2. You need enough battery capacity to carry you through the longest expected periods without sun
3. You need enough panels to recharge quickly while still running normal loads

If you boondock in moderate climates with abundant sunshine it all works really well.

But if one boondocks in the Pacific Northwest where one, two, or sometimes three weeks of cloudy skies and rain are common, the battery capacity needed to carry them through that weather is substantial. To recharge quickly (say a couple days), while also running the normal loads, would take a substantial amount of panes on the roof or ground. It would be a very large system that wouldn’t fit on most class B, B+, or C’s, and perhaps many of the smaller A’s or Fifth Wheels.

Someone boondocking in Florida in the summer months has abundant sunshine but has increased their energy needs significantly due to the need to run an AC. Parking in the sun isn’t desired due to heat build up, so they may need ground panels. And a large array of panels on the ground may not be possible where they are staying. AC could be needed day and night during the hottest summer months. Large energy demands that are expensive and require much more space to mitigate the higher demands.

Throw in the northern US states in the fall, winter, and spring, with cold nights, cloudy skies, the demand for heat, and again you end up with demands that exceed even a decent solar and battery system. The propane can supply the heat, but the fans are power hungry and have high duty cycles, and there is a significant lack of decent sunshine.

When one can chase moderate/mild climates, follow the sun and 70F weather, such as out west using elevation to control ambient temperature and the abundance of sunshine, it’s pretty easy to rely 100% on solar. But thats an ideal situation the majority of the country doesn’t share.
?I live in the Northeast, travel south, and routinely boondock all up and down the eastern seaboard. Northeast we have challenges with enough sunlight during parts of the year, southeast with excessive heat and humidity, and further north with cold temps and heating demands. The needs in these climates tend to stress even decent solar systems once you hit several days with no sun and high demands.

When temps are reasonable and the sun is shinning, my meager 100w panel and 100AH battery on my small class B does wonderful, even with both refrigerators. But when the sun disappears for more than a few days the quick press of the generator button brings them back up to charge in a couple hours and I’m good for another 3 or 4 days. When in Florida, boondocking in the hot sun and high humidity, the generator gets its exercise, as does the AC 🙂

My last Class A had 400w and 4 6v batts. It was fine in moderate temps and sunny climates, but not so much in the hot humid south or colder northern climates.

crosscheck wrote:

The OP question was How much solar do I need to run this fridge? Answers were everything from 200W-600W, 2 batteries to 6 batteries. The OP will decide on what will work for them and go from there.

Reflex 439, you have stated that solar does not do a very good job as a stand alone for taking care of the electrical wants of the modern RVer. I understand that everyones electrical needs are different but your own solar wattage of 100W and battery storage of 100AH is very different than many on this forum who have replaced generators completely or at least cut down operating times due to their descent sized solar/battery upgrades. And with portable solar, you can be in the trees and still harvest solar with a long enough cord and a portable unit.

Since 2011, our camping style is 98% dry/boondocking and we have almost 100% eliminated generator times with solar and battery storage. Never need A/C as we avoid very hot places and use high efficient 12V fans at night when it is hot. On our previous RV, had 330W solar and 4 AGM 6V batteries and ran a 12V, 7.5cuft compressor fridge freezer. Almost never ran the genny. Now we have 490W and 4 6V GC2,s and a 2000W inverter and Micro and we have power to spare.

2 simple ways of lower running times or eliminating genny run times are using less power(LED's, more efficient TV's etc,) or increasing solar and battery storage.

If we had to dry/boondock on your modest solar/battery set up, the genny would come out of retirement real quick.

Dave

[pianotuna]

Hi,

2400 watts of panels with a 48 volt 500 amp-hour (24 kwh) Battleborn battery bank would easily run from solar with NO caveats.

Reflex439 wrote:

pianotuna wrote:
Reflex439,
There are numbers of folks who now have the ability to run their roof air conditioner from solar panels. Running a fridge like yours would be a snap.

It is a snap. I do it on a single 100w panel easily.

But ask those that run their ACs off solar and battery power how long they can do so. You won't find them parked in the sun running their ACs all day. I've had many people talk about how their latest lithium powered solar rig could run their air conditioner. But then the caveats start piling up.

[crosscheck]

crosscheck wrote:

Reflex439 wrote:
All the above, but also keep in mind for the solar panels to work well you need to always park in the sun. That creates a very hot box in which to live unless you stay in cooler climates. If you park in the shade to keep cool, even partially putting the solar panels in shade can drop the solar output by 90% or more.

Solar is great to augment other power sources, but is very inefficient as a standalone source. If used with a small generator an hour or so a day, and or driving daily, they are great at helping keeping things topped off. But if in the shade, cloudy day, and no other power source, it will deplete the batteries rather quickly and could take more than a couple days to recover and top off the batteries.

Most RV's don't have the roof space to put enough panels to really run all the electrical systems within them. But the solar panels put in enough to reduce the generator or driving time needed to fully recharge. If only running low draw items (USB, LED lighting, CO monitors, low voltage circuits in propane refrigerators, etc, a 100AH battery and a 100W solar with MPPT controller is more than adequate.

As one other reference, I have a 100AH (maybe 110AH, don't remember), a supplemental Dometic CFX28 Danfoss refrigerator (top open cooler style), the factory 3 way refrig I run on propane, and LED lights, 12v TV/DVD, USB chargers, and small 600W invert I use for my laptop. I can regularly get a couple days on the 12V battery and solar setup. But the Danfoss refrig uses about 3-4amps on a 50% duty cycle where the 3 Way uses nearly 11amp at a higher duty cycle.

The 3-way refrig on 12v is awful at regulating temperature to the point that I have to adjust the temp setting multiple times a day. At night it would freeze, and in the day wouldn't cool well enough. So you have to ride the temp setting lowing it when the temps drop, and raising it when the sun and temps start to heat up. The Dometic CFX28 is a set and forget, and will keep everything within a few degrees regardless of the outside temps, all while using far less energy. I use the 3way for cold drinks, produce, and other non-critical foods. Anything critical goes in the CFX28. I love having both as it also doubles my refrigerator capacity.

Hope this info helps.

The OP question was How much solar do I need to run this fridge? Answers were everything from 200W-600W, 2 batteries to 6 batteries. The OP will decide on what will work for them and go from there.

Reflex 439, you have stated that solar does not do a very good job as a stand alone for taking care of the electrical wants of the modern RVer. I understand that everyones electrical needs are different but your own solar wattage of 100W and battery storage of 100AH is very different than many on this forum who have replaced generators completely or at least cut down operating times due to their descent sized solar/battery upgrades. And with portable solar, you can be in the trees and still harvest solar with a long enough cord and a portable unit.

Since 2011, our camping style is 98% dry/boondocking and we have almost 100% eliminated generator times with solar and battery storage. Never need A/C as we avoid very hot places and use high efficient 12V fans at night when it is hot. On our previous RV, had 330W solar and 4 AGM 6V batteries and ran a 12V, 7.5cuft compressor fridge freezer. Almost never ran the genny. Now we have 490W and 4 6V GC2,s and a 2000W inverter and Micro and we have power to spare.

2 simple ways of lower running times or eliminating genny run times are using less power(LED's, more efficient TV's etc,) and increasing solar and battery storage.

If we had to dry/boondock on your modest solar/battery set up, the genny would come out of retirement real quick.

Dave

[crosscheck]

Reflex439 wrote:
All the above, but also keep in mind for the solar panels to work well you need to always park in the sun. That creates a very hot box in which to live unless you stay in cooler climates. If you park in the shade to keep cool, even partially putting the solar panels in shade can drop the solar output by 90% or more.

Solar is great to augment other power sources, but is very inefficient as a standalone source. If used with a small generator an hour or so a day, and or driving daily, they are great at helping keeping things topped off. But if in the shade, cloudy day, and no other power source, it will deplete the batteries rather quickly and could take more than a couple days to recover and top off the batteries.

Most RV's don't have the roof space to put enough panels to really run all the electrical systems within them. But the solar panels put in enough to reduce the generator or driving time needed to fully recharge. If only running low draw items (USB, LED lighting, CO monitors, low voltage circuits in propane refrigerators, etc, a 100AH battery and a 100W solar with MPPT controller is more than adequate.

As one other reference, I have a 100AH (maybe 110AH, don't remember), a supplemental Dometic CFX28 Danfoss refrigerator (top open cooler style), the factory 3 way refrig I run on propane, and LED lights, 12v TV/DVD, USB chargers, and small 600W invert I use for my laptop. I can regularly get a couple days on the 12V battery and solar setup. But the Danfoss refrig uses about 3-4amps on a 50% duty cycle where the 3 Way uses nearly 11amp at a higher duty cycle.

The 3-way refrig on 12v is awful at regulating temperature to the point that I have to adjust the temp setting multiple times a day. At night it would freeze, and in the day wouldn't cool well enough. So you have to ride the temp setting lowing it when the temps drop, and raising it when the sun and temps start to heat up. The Dometic CFX28 is a set and forget, and will keep everything within a few degrees regardless of the outside temps, all while using far less energy. I use the 3way for cold drinks, produce, and other non-critical foods. Anything critical goes in the CFX28. I love having both as it also doubles my refrigerator capacity.

Hope this info helps.

The OP question was How much solar do I need to run this fridge? Answers were everything from 200W-600W, 2 batteries to 6 batteries. The OP will decide on what will work for them and go from there.

Reflex 439, you have stated that solar does not do a very good job as a stand alone for taking care of the electrical wants of the modern RVer. I understand that everyones electrical needs are different but your own solar wattage of 100W and battery storage of 100AH is very different than many on this forum who have replaced generators completely or at least cut down operating times due to their descent sized solar/battery upgrades. And with portable solar, you can be in the trees and still harvest solar with a long enough cord and a portable unit.

Since 2011, our camping style is 98% dry/boondocking and we have almost 100% eliminated generator times with solar and battery storage. Never need A/C as we avoid very hot places and use high efficient 12V fans at night when it is hot. On our previous RV, had 330W solar and 4 AGM 6V batteries and ran a 12V, 7.5cuft compressor fridge freezer. Almost never ran the genny. Now we have 490W and 4 6V GC2,s and a 2000W inverter and Micro and we have power to spare.

2 simple ways of lower running times or eliminating genny run times are using less power(LED's, more efficient TV's etc,) or increasing solar and battery storage.

If we had to dry/boondock on your modest solar/battery set up, the genny would come out of retirement real quick.

Dave

[Reflex439]

pianotuna wrote:
Reflex439,
There are numbers of folks who now have the ability to run their roof air conditioner from solar panels. Running a fridge like yours would be a snap.

It is a snap. I do it on a single 100w panel easily.

But ask those that run their ACs off solar and battery power how long they can do so. You won't find them parked in the sun running their ACs all day. I've had many people talk about how their latest lithium powered solar rig could run their air conditioner. But then the caveats start piling up. They can only run it for a portion of the day, and then it takes a couple days to put back all the energy they sucked out if only relying on their solar system. If they drove every day for a couple hours, or ran their generators, they could top off the batteries sooner. So they were still reliant on external power sources, such as generators, alternator charging, or shore power if they wanted to run their AC for more than one day.

It reminds me of a Tesla. You can get 300 or so miles on a full charge, but then you are sitting in a parking lot for 4-6 hours in order to fill your tank, or 3 hours at a high speed home station. Sure, they can run their car down the highway at 70mph, but terrible for long term traveling. So yea, you can run your AC off solar and batteries, but you will be spending a few days of limiting your electrical usage trying to recover your lost energy if all you have is your solar. God forbid it turns partially cloudy, or worse overcast.

[pianotuna]

Reflex439,

There are numbers of folks who now have the ability to run their roof air conditioner from solar panels. Running a fridge like yours would be a snap.

[Reflex439]

All the above, but also keep in mind for the solar panels to work well you need to always park in the sun. That creates a very hot box in which to live unless you stay in cooler climates. If you park in the shade to keep cool, even partially putting the solar panels in shade can drop the solar output by 90% or more.

Solar is great to augment other power sources, but is very inefficient as a standalone source. If used with a small generator an hour or so a day, and or driving daily, they are great at helping keeping things topped off. But if in the shade, cloudy day, and no other power source, it will deplete the batteries rather quickly and could take more than a couple days to recover and top off the batteries.

Most RV's don't have the roof space to put enough panels to really run all the electrical systems within them. But the solar panels put in enough to reduce the generator or driving time needed to fully recharge. If only running low draw items (USB, LED lighting, CO monitors, low voltage circuits in propane refrigerators, etc, a 100AH battery and a 100W solar with MPPT controller is more than adequate.

As one other reference, I have a 100AH (maybe 110AH, don't remember), a supplemental Dometic CFX28 Danfoss refrigerator (top open cooler style), the factory 3 way refrig I run on propane, and LED lights, 12v TV/DVD, USB chargers, and small 600W invert I use for my laptop. I can regularly get a couple days on the 12V battery and solar setup. But the Danfoss refrig uses about 3-4amps on a 50% duty cycle where the 3 Way uses nearly 11amp at a higher duty cycle.

The 3-way refrig on 12v is awful at regulating temperature to the point that I have to adjust the temp setting multiple times a day. At night it would freeze, and in the day wouldn't cool well enough. So you have to ride the temp setting lowing it when the temps drop, and raising it when the sun and temps start to heat up. The Dometic CFX28 is a set and forget, and will keep everything within a few degrees regardless of the outside temps, all while using far less energy. I use the 3way for cold drinks, produce, and other non-critical foods. Anything critical goes in the CFX28. I love having both as it also doubles my refrigerator capacity.

Hope this info helps.

[pianotuna]

Duty cycle (measured) on my rv is 2:3 (on 40 minutes per hour) with the door never being opened with ambient temperature of about 16 c (61 f).

[time2roll]

thriftydutch wrote:
I just found this info on the fridge.
120 volts 0.4 amps
12 volt 4.0 amps
The batteries I have are 115 amp hours each.

OK you have about 100 amp hours usable and assuming 50% duty cycle you need 50 amps hours per day. So you need 10 amps to the battery for 5 hours so 200 watts solar minimum in good conditions. That is just the fridge. I would still be at 3 to 4 batteries and 400+ watts solar to do this comfortably. Not an exact science, lots of variables. Solar will need to produce more than you use. Very easy to come up short doing a minimum calculation.

[pianotuna]

Does the fridge work well on the 12 volt setting?

12 x 4 = 48 watts x 24 hours = 1152 watt-hours.

1152 watt-hours / 5 = 230 watts of panels. However one needs to be able to recharge the battery bank, too! I'd go with at least 400 watts on a flat fixed installation.

twin 115 amp-hour batteries would yield about 1300 watt-hours usable.

That would allow for only one "grey day" before another source of power for the fridge would be needed.

[thriftydutch]

I just found this info on the fridge.
120 volts 0.4 amps
12 volt 4.0 amps
The batteries I have are 115 amp hours each.

[crosscheck]

time2roll wrote:
Manual just says max 15 amp fuse
I assume this fridge draws 10/12 amps at 12v near continuous.

The minimum I see is 6 batteries and 600+ watts solar.

Plan to have a small generator to use as needed. With a generator you can get by with less battery and solar until you see what works.

This is why most use a propane fridge.

Read the yachting forums. These 40 year old fridges are thrown overboard and replaced with modern Danfoss compressor, 12V DC fridge/Freezers that are much more reliable and use 1/3 the amps. 200W solar and 2 6V GC2,s are what you would need extra for a modern 12V compressor fridge. For what the OP has, at least 3 times that amount. My 5 years experience with a similar sized 12V fridge as the OP is that 50% cycling was the max for us depending on as many as 6 factors which adds up to around 65AH/day being the highest draw/day.


Dave

[time2roll]

Manual just says max 15 amp fuse
I assume this fridge draws 10/12 amps at 12v near continuous.

The minimum I see is 6 batteries and 600+ watts solar.

Plan to have a small generator to use as needed. With a generator you can get by with less battery and solar until you see what works.

This is why most use a propane fridge.