Solar Powered refrigerator project

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HarryN
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Solar Powered refrigerator project

Post by HarryN » Mon Feb 07, 2022 11:49 am

Hi, I build solar generators for various uses, including I have one for powering the side x side refrigerator / freezer in my garage.

I would like to work with a camp or someone to do a project like this out on the playa. Sort of a "free use of a section of a refrigerator or freezer shelf" for people that need something like that.

My motivation is that I do some volunteer work in disaster relief and would like to test one under tough / dusty conditions, by people who don't really take very good care of things, but still have someone around who can deal with challenges as they come up.

I have been trying to do this at BM for about 4-5 years, but either I could not purchase a ticket, covid, or this past year I was in an accident and was in recovery / could not work as much like before.

I am 63, so not exactly a typical burner and I am unsure if I can really attend in 2022 for health reasons, but can work with people or a team locally (SF bay area). I live in the east bay near 580 / 680.

The technical aspects of solar / battery / inverter design / selection are not really a problem, so that part is relatively easy for me.

The details related to a solar panel setup that can actually withstand the conditions are BM are more exciting to figure out and I could use some advice in that area.

Size wise, they are roughly the size of full size suite case, so ~ 12 x 20 x 30 inches.

My initial idea was to use a heavy duty ladder and mount the solar panels on it - some facing east, some facing west.

Open to ideas / suggestions or if anyone or any teams would like to participate.

Thanks

Harry

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some seeing eye
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Re: Solar Powered refrigerator project

Post by some seeing eye » Mon Feb 07, 2022 3:59 pm

Hello Mr HarryN,

That is a great project! Are you aware of the Alternative Energy Zone village? They are primarily organized by https://aezone.wixsite.com/ae-zone and an email list [email protected]. They also have a weekly Zoom on Saturday morning.

They a no generator camp, home to all kinds of demonstration projects. That ranges from solar oven cookies, the solar death ray, and many solar + battery setups. They offer tours for the curious and advice. They know how dust meets electricity.

I would contact them. Usually they would have camps within the village. They certainly have campers in your area.

A significant solar camp is Snow Koan Solar which is part of Nectar Village. They are not accepting new members and they scaled back after their founder passed in a motorcycle accident. They are pretty easy to look up but no guarantee of interest.

Camp Hotel California published their solar setup, batteries and electronics in a plastic tub, on Github.

The other groups to reach out to, if you like, are Black Rock Labs, Fly Ranch, and the Sustainability Roadmap people at BMORG. You might also find interest at Burners Without Borders.

Best with your adventure!

(There have been some solar threads on ePlaya if that is of interest)
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HarryN
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Re: Solar Powered refrigerator project

Post by HarryN » Fri Feb 11, 2022 11:06 am

Thank you for the ideas for more places to look for information.

1) Various "solar related", generator, camp power and "how to stay cool" threads
- Although I have not posted very much, I actually have read those threads in quite a bit of detail
- Over the past few years, I even went so far as look at 3 different ways of estimating what is needed in evaporation based cooling on the playa and ran a small test setup in my driveway when it was 110 F one day.

- Thank you for the suggestions - will continue to read / look

2) Camp Hotel California project
- I was not aware of this project - thank you.
- I hope that it is ok for me to make link to it for easier navigation / quick finding it.

https://github.com/hotelcaliforniabm/arc

- They have done an excellent job to design a 24 volt battery based / solar power setup at a moderate price.
- By using 24 volt DC refrigerators, this eliminates the need for an inverter - which is quite a cost saving, and makes perfect sense for use in RVs and camping type situations.
- Clearly they have a solid understanding of what is involved in running a solar powered setup under those conditions.

Similarly, the system that I have designed for this refrigerator application is also 24 volt based, but since the end users will primarily have 120 vac or similar AC type power requirements, I built in the inverter as well.

Since the typical application that I am working on will need to operate for much longer than a few weeks, and possibly be handled even less lovingly than a BM event, I build them with a much tougher / heavy duty case.

Nothing at all wrong with their design - it is a good setup for the targeted application.

There are some great ideas in that design though - so it is definitely useful for people to consider.
Last edited by HarryN on Fri Feb 11, 2022 11:26 am, edited 1 time in total.

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Re: Solar Powered refrigerator project

Post by HarryN » Fri Feb 11, 2022 11:08 am

some seeing eye wrote:
Mon Feb 07, 2022 3:59 pm
Hello Mr HarryN,

That is a great project! Are you aware of the Alternative Energy Zone village? They are primarily organized by https://aezone.wixsite.com/ae-zone and an email list [email protected]. They also have a weekly Zoom on Saturday morning.

They a no generator camp, home to all kinds of demonstration projects. That ranges from solar oven cookies, the solar death ray, and many solar + battery setups. They offer tours for the curious and advice. They know how dust meets electricity.

I would contact them. Usually they would have camps within the village. They certainly have campers in your area.
Thank you - I will look into this.

To be honest - for me, it is more complicated to navigate the many meetings / emails and other sort of abstract stuff related to BM /camp then it is to just build things.

I never did figure out how to actually purchase a ticket before they were all sold out several years in a row.

That is one of the things that made 2021 very interesting. I would have gone if not for the accident.

I will try to see if I can stand sitting through a weekly zoom meeting with a group but probably it is worth it.

Appreciate the info.

_

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Re: Solar Powered refrigerator project

Post by HarryN » Fri Feb 11, 2022 11:23 am

The funny thing is that in the past, I actually built a power system for a camp, but was not able to get a ticket or go to BM.

The application was exactly the same - refrigeration via solar.

It ended up not happening for 2 reasons:
- The group ran out of space to take it along
- The camp cook was nervous about the concept of powering the refrigeration off of solar vs a generator, and for some reason didn't connect the idea that a refrigerator and freezer are the same to someone like me.

Maybe I can find a local camp group that is interested in this concept.

One suggesting that I received was to make it into a "mutant car" concept. That is one step beyond what I can do alone.

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Re: Solar Powered refrigerator project

Post by Token » Fri Feb 11, 2022 1:46 pm

Chest freezers are the way to go for this.

Few exceed couple few hundred watt of power.

The trick is behavioral adjustment.

Chest freezers require a cold mass inside them to run optimally. Even more so when they run as refrigerators.

If designing for longevity, it’s probably best to stick with a 24V designed unit that can handle both freezer and refrigerator duty cycles.

The dedicated solar models also have lower inrush current, as the designers didn’t assume practically infinite power delivery of a 20A 120v plug. That goes a long way towards battery life in a solar system.

The 24V models used to cost a mint back in the day, but prices have come down to earth and are competitive with 120V AC models.

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Re: Solar Powered refrigerator project

Post by HarryN » Fri Feb 11, 2022 3:20 pm

Token wrote:
Fri Feb 11, 2022 1:46 pm
Chest freezers are the way to go for this.

Few exceed couple few hundred watt of power.

The trick is behavioral adjustment.

Chest freezers require a cold mass inside them to run optimally. Even more so when they run as refrigerators.

If designing for longevity, it’s probably best to stick with a 24V designed unit that can handle both freezer and refrigerator duty cycles.

The dedicated solar models also have lower inrush current, as the designers didn’t assume practically infinite power delivery of a 20A 120v plug. That goes a long way towards battery life in a solar system.

The 24V models used to cost a mint back in the day, but prices have come down to earth and are competitive with 120V AC models.
Thank you for the input.

For BM or camping use in general, I agree.

In this particular situation, what I am actually looking for is to have a team / group use it with a 120 vac refrigerator or freezer at BM as a way to test what can go wrong.

Hopefully nothing as this "solar generator design" is already in regular use at my house running a side x side refrigerator / freezer (and a few other locations) , but the playa environment and somewhat uncontrolled user behavior is a good way to make things fail.

Ultimately these "solar generators" will be used to help with my volunteer work with disaster relief and similar, and at least some of those will be 120 vac refrigerators / freezers. In those situations, both human and environmental conditions control are also somewhat unpredictable, so BM is a good test.

This means that the group will need to have experience / own a 120 vac refrigerator or freezer, possibly some solar panels, and a viable means to bring it all from the SF Bay area to BM.

An example would be a camp that might normally run their refrigeration / freezer needs from a generator, but is willing to use this system instead as a test, perhaps with the normal generator power available as a back up plan. I don't want to risk ruining a camp's food supply, even though it seems unlikely - I cannot be 100% certain.

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Re: Solar Powered refrigerator project

Post by Token » Fri Feb 11, 2022 4:44 pm

HarryN wrote:
Fri Feb 11, 2022 3:20 pm
Token wrote:
Fri Feb 11, 2022 1:46 pm
Chest freezers are the way to go for this.

Few exceed couple few hundred watt of power.

The trick is behavioral adjustment.

Chest freezers require a cold mass inside them to run optimally. Even more so when they run as refrigerators.

If designing for longevity, it’s probably best to stick with a 24V designed unit that can handle both freezer and refrigerator duty cycles.

The dedicated solar models also have lower inrush current, as the designers didn’t assume practically infinite power delivery of a 20A 120v plug. That goes a long way towards battery life in a solar system.

The 24V models used to cost a mint back in the day, but prices have come down to earth and are competitive with 120V AC models.
Thank you for the input.

For BM or camping use in general, I agree.

In this particular situation, what I am actually looking for is to have a team / group use it with a 120 vac refrigerator or freezer at BM as a way to test what can go wrong.

Hopefully nothing as this "solar generator design" is already in regular use at my house running a side x side refrigerator / freezer (and a few other locations) , but the playa environment and somewhat uncontrolled user behavior is a good way to make things fail.

Ultimately these "solar generators" will be used to help with my volunteer work with disaster relief and similar, and at least some of those will be 120 vac refrigerators / freezers. In those situations, both human and environmental conditions control are also somewhat unpredictable, so BM is a good test.

This means that the group will need to have experience / own a 120 vac refrigerator or freezer, possibly some solar panels, and a viable means to bring it all from the SF Bay area to BM.

An example would be a camp that might normally run their refrigeration / freezer needs from a generator, but is willing to use this system instead as a test, perhaps with the normal generator power available as a back up plan. I don't want to risk ruining a camp's food supply, even though it seems unlikely - I cannot be 100% certain.
If 120Vac is a requirement, no big deal really.

It’s a matter of finding the right inverter for the environment; preferably one that has no cooling fans and is designed for passive heat radiation only.

Once the thermals are figured out, the next thing is the locked-rotor current for compressor startup: that can be handled by a good size startup capacitor. Dampens any power surges on the inverter and batteries.

It’s fun stuff.

I did mine with 200W solar, 1000W inverter, and a random capacitor I had from an HVAC.

Does well when PG&E cuts our power in the middle of summer for wildfire reasons.

My bacon is safe!

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Re: Solar Powered refrigerator project

Post by HarryN » Sat Feb 12, 2022 7:56 am

Thanks - I am attempting to load a photo - will see if it works.

For the past 10 years, I have been building conversion van electrical systems, mostly in the 2 - 4 kW range.

After the hurricane hit PR, I started on the design of a smaller system to help with post disaster support. Like most projects, it take longer than hoped to shoe horn it all into a suitcase size system.

The one in the photo with my friend Ryan and the 3 panels was V 2, with the batteries, solar charger, 120 vac charger, 1100 watt, commercial grade inverter, etc inside. This was actually built for use at BM by a local camp, but at the last minute, there wasn't space to bring it along.

I am in the middle of updating it to V3.x with a larger battery pack and some other enhancements, including a less heat absorbing color, and a larger set of wheels for going across the dirt.

It is still limited to 800 watts of solar at this time, but that can be 800 watts facing morning sun and 800 watts facing the evening sun.

Power a home refrigerator is a non issue. I use it to power a 1400 watt microwave, my power tools, coffee maker, etc all of the time, as my shop is completely off grid.

Since I have never been able to purchase a BM ticket or go in the past 5 years, I am looking for a camp that I can work with to use this this at BM in a refrigeration / freezer application, and test how it does in the conditions of hot, dust and people who are not trained or thinking completely clearly. This mimics the real world of post disasters.

I would like to go, but I am still recovering from an accident so it is unlikely that I will be able to.
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Re: Solar Powered refrigerator project

Post by prussianblue » Tue Feb 15, 2022 12:55 pm

Name is Doug. I am part of the Renewables for Artists Team (RAT) and we are working with artists to get off the generators and power playa art with solar. We are ALWAYS looking for folks to join us. We are a small team but work very hard. We all have had solar systems on playa, most DIY. For 2022 we are mentoring a dozen different artists who are brining art to the playa. RAT has training material on Hive. And you can reach out to me at [email protected].

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Re: Solar Powered refrigerator project

Post by HarryN » Tue Feb 15, 2022 10:21 pm

Thanks Doug - I will send an email.

As long as the art project meets my primary goal of powering a full size, 120 vac refrigerator (that is really used for something good for people) as a fundamental part of it, that is perfectly fine.

This particular unit is pretty optimized for the refrigeration application.

It might be that something quite a bit less substantial would be needed for artistic endeavours, and I am open to assisting with that area as it makes sense.

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Re: Solar Powered refrigerator project

Post by HarryN » Wed Feb 16, 2022 5:58 am

Last night I did a quick calculation related to power availability for "other uses".

Rough numbers, there is a spare 100 watts available.

My plan had been to use this for charging devices but it could be used for other things as well.

HarryN

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Re: Solar Powered refrigerator project

Post by motskyroonmatick » Fri Feb 18, 2022 1:08 am

I've been thinking of building out 2 or 3 of these solar powered solar chest freezer/refrigerators for a while. I'll share the results of my build and testing here.
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Re: Solar Powered refrigerator project

Post by motskyroonmatick » Tue Jun 21, 2022 9:08 pm

motskyroonmatick wrote:
Fri Feb 18, 2022 1:08 am
I've been thinking of building out 2 or 3 of these solar powered solar chest freezer/refrigerators for a while. I'll share the results of my build and testing here.
Here is my test setup to see how well a 220 watt solar panel powers at Costco Freezer hacked in to a refrigerator.



At this time it powers it great after 26 hours of operation. I started with a not quite topped off battery and bulk charging was 10 hours today after finishing the system and plugging it in last night. Yield of the solar charger was 520wh. As expected there is a bit of a high draw when the compressor starts up but it evens out at 104 watts while running. It was finally sunny today and the battery was topped off nicely when I got home. Refrigerator is in box truck which is closed and is basically an oven when it's sunny so I think this is a good stress test. It's full of beverages so there is lots of thermal mass. I've got a temperature data logger measuring the temperature of the compressor fan output so I can see what the operating temperature is and count the cycles of operation. It's a fun little experiment and it's coming to the playa.
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Re: Solar Powered refrigerator project

Post by ygmir » Wed Jun 22, 2022 6:20 am

motskyroonmatick wrote:
Tue Jun 21, 2022 9:08 pm
motskyroonmatick wrote:
Fri Feb 18, 2022 1:08 am
I've been thinking of building out 2 or 3 of these solar powered solar chest freezer/refrigerators for a while. I'll share the results of my build and testing here.
Here is my test setup to see how well a 220 watt solar panel powers at Costco Freezer hacked in to a refrigerator.



At this time it powers it great after 26 hours of operation. I started with a not quite topped off battery and bulk charging was 10 hours today after finishing the system and plugging it in last night. Yield of the solar charger was 520wh. As expected there is a bit of a high draw when the compressor starts up but it evens out at 104 watts while running. It was finally sunny today and the battery was topped off nicely when I got home. Refrigerator is in box truck which is closed and is basically an oven when it's sunny so I think this is a good stress test. It's full of beverages so there is lots of thermal mass. I've got a temperature data logger measuring the temperature of the compressor fan output so I can see what the operating temperature is and count the cycles of operation. It's a fun little experiment and it's coming to the playa.
Nice looking set up Motz!
I'll look forward to seeing how this goes. I'd like to do the same, for the same reasons as Token, when our power is shut off during fire season.
Is a "pure sine wave" inverter required for a freezer? IIRC, the modified sine wave is ok for motors?
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Re: Solar Powered refrigerator project

Post by Token » Wed Jun 22, 2022 8:22 am

That is all kinds of nice and tidy. Great job and extra special ⭐️ for attention to detail.

Breakers, thick cables, heat-shrink connector ends …

… gotta clean up that tape near the inverter on the battery + lead … ;)

The duty cycle is the interesting number to capture, especially if you can keep the trailer ~ 100f during the daytime hours. If you can capture the total energy used in a 24 hour cycle over several days … swap that 60# battery with some lightweight Li Ion. That would be the schnitzel. Maybe I’m getting old …

Also perfect time to test with the Solstice.

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Re: Solar Powered refrigerator project

Post by motskyroonmatick » Wed Jun 22, 2022 9:01 pm

ygmir wrote:
Wed Jun 22, 2022 6:20 am

Is a "pure sine wave" inverter required for a freezer? IIRC, the modified sine wave is ok for motors?
I'm not sure. I do know at one point I made the decision to only buy pure sine wave inverters because there is a scenario where modified sine wave are not healthy to electronics and I wanted to avoid that. It was a decide and forget why moment.

Thanks for the compliment.
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Re: Solar Powered refrigerator project

Post by motskyroonmatick » Wed Jun 22, 2022 9:31 pm

Token wrote:
Wed Jun 22, 2022 8:22 am
That is all kinds of nice and tidy. Great job and extra special ⭐️ for attention to detail.

Breakers, thick cables, heat-shrink connector ends …

… gotta clean up that tape near the inverter on the battery + lead … ;)

The duty cycle is the interesting number to capture, especially if you can keep the trailer ~ 100f during the daytime hours. If you can capture the total energy used in a 24 hour cycle over several days … swap that 60# battery with some lightweight Li Ion. That would be the schnitzel. Maybe I’m getting old …

Also perfect time to test with the Solstice.
Thanks!

Yep there is a little touching up that could be done covering studs and fasteners.

Today the charger worked a little harder with around 650wh charged in 7 hours.

The battery is a LiFePo4 and it's not tooooo heavy. That is my preferred chemistry at the moment.

It is interesting to see that it works at max charge time of the year... I have the distinct awareness that the system has it's best chance for functioning well right now and that may change with shorter day length. Roughly using half of the capacity of the battery on a daily basis seems like there is a bit of a reserve for poor charging days but not walk away from it for a week kind of reserve.

My data logger chart didn't convey on off cycles very well so I've changed that up to hopefully read the cycles better.

Fun stuff.
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Re: Solar Powered refrigerator project

Post by ygmir » Thu Jun 23, 2022 6:03 am

motskyroonmatick wrote:
Wed Jun 22, 2022 9:31 pm
Token wrote:
Wed Jun 22, 2022 8:22 am
That is all kinds of nice and tidy. Great job and extra special ⭐️ for attention to detail.

Breakers, thick cables, heat-shrink connector ends …

… gotta clean up that tape near the inverter on the battery + lead … ;)

The duty cycle is the interesting number to capture, especially if you can keep the trailer ~ 100f during the daytime hours. If you can capture the total energy used in a 24 hour cycle over several days … swap that 60# battery with some lightweight Li Ion. That would be the schnitzel. Maybe I’m getting old …

Also perfect time to test with the Solstice.
Thanks!

Yep there is a little touching up that could be done covering studs and fasteners.

Today the charger worked a little harder with around 650wh charged in 7 hours.

The battery is a LiFePo4 and it's not tooooo heavy. That is my preferred chemistry at the moment.

It is interesting to see that it works at max charge time of the year... I have the distinct awareness that the system has it's best chance for functioning well right now and that may change with shorter day length. Roughly using half of the capacity of the battery on a daily basis seems like there is a bit of a reserve for poor charging days but not walk away from it for a week kind of reserve.

My data logger chart didn't convey on off cycles very well so I've changed that up to hopefully read the cycles better.

Fun stuff.
fun indeed!
Just to be clear for me (often dense): Are you using the freezer as a freezer or fridge? I know there is a way do both, and wonder how to do that? I have a few 220W panels still, been sitting in my shop for years, but never hooked up.
On a side note, I have a dozen "grid tie" inverters, that I'd love to find a way to trick them into working direct. Enphase 210's (IIRC). Again, only hooked up once to see if they actually worked, been sitting and I've no plan to grid tie them, due to county and PGE regulations here in my area. Along with the new PRC tax on generating your own solar power...
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Re: Solar Powered refrigerator project

Post by Popeye » Thu Jun 23, 2022 9:49 am

motskyroonmatick wrote:
Wed Jun 22, 2022 9:01 pm
ygmir wrote:
Wed Jun 22, 2022 6:20 am

Is a "pure sine wave" inverter required for a freezer? IIRC, the modified sine wave is ok for motors?
I'm not sure. I do know at one point I made the decision to only buy pure sine wave inverters because there is a scenario where modified sine wave are not healthy to electronics and I wanted to avoid that. It was a decide and forget why moment.

Thanks for the compliment.
The electronics are pretty much the same for inverters and Motor Speed Controllers/ AC Drives which we used to convert single phase AC to three phase. Twenty some years ago we had a lot of problems with motor windings arcing to the bearings in Maneurope compressors. We finally traced this to the AC Drives. Changing manufacturers cured the problem.
Also there is a known problem with buildings using a LOT of computer equipment overloading the neutral with third order harmonics generated by computer power supplies. After a few buildings burnt down there was a NEC Code change eliminating reduced sized neutrals.
I wouldn't use a modified sine wave on electronic equipment. You can probably get away with it if that's what you have but not worth it if buying new inverters.
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Re: Solar Powered refrigerator project

Post by Token » Thu Jun 23, 2022 6:37 pm

ygmir wrote:
Thu Jun 23, 2022 6:03 am
.
On a side note, I have a dozen "grid tie" inverters, that I'd love to find a way to trick them into working direct. Enphase 210's (IIRC). Again, only hooked up once to see if they actually worked, been sitting and I've no plan to grid tie them, due to county and PGE regulations here in my area. Along with the new PRC tax on generating your own solar power...
Not worth the bother for just 12 units. 200W each … meh.

UL-1741SA If you really want to geek out on it …

TL;DR - you can fake a “grid” with a standalone panel, battery and 3-phase inverter that supports that UL standard - and the SA in the standard is critical. The SA part let’s the inverter do the frequency shifting magic crap to sync all the parts - like Honda generators in parallel …

That fake “grid” will cost way more than the microinverters.

Sell them on EBay and get the M250 where they support off-grid would be my advice.

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Re: Solar Powered refrigerator project

Post by Token » Thu Jun 23, 2022 6:39 pm

Motsky! You’re a Mensch!!!

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Re: Solar Powered refrigerator project

Post by ygmir » Thu Jun 23, 2022 7:07 pm

Popeye wrote:
Thu Jun 23, 2022 9:49 am
motskyroonmatick wrote:
Wed Jun 22, 2022 9:01 pm
ygmir wrote:
Wed Jun 22, 2022 6:20 am

Is a "pure sine wave" inverter required for a freezer? IIRC, the modified sine wave is ok for motors?
I'm not sure. I do know at one point I made the decision to only buy pure sine wave inverters because there is a scenario where modified sine wave are not healthy to electronics and I wanted to avoid that. It was a decide and forget why moment.

Thanks for the compliment.
The electronics are pretty much the same for inverters and Motor Speed Controllers/ AC Drives which we used to convert single phase AC to three phase. Twenty some years ago we had a lot of problems with motor windings arcing to the bearings in Maneurope compressors. We finally traced this to the AC Drives. Changing manufacturers cured the problem.
Also there is a known problem with buildings using a LOT of computer equipment overloading the neutral with third order harmonics generated by computer power supplies. After a few buildings burnt down there was a NEC Code change eliminating reduced sized neutrals.
I wouldn't use a modified sine wave on electronic equipment. You can probably get away with it if that's what you have but not worth it if buying new inverters.
do you include motors in this? IE, a freezer?

@Token:
where does the 3 phase fit in? I'm sorta confused by that, in that I'm making single phase?
Fair admission: I don't know much about this solar/inverter/converter/battery stuff...
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Re: Solar Powered refrigerator project

Post by motskyroonmatick » Thu Jun 23, 2022 7:55 pm

ygmir wrote:
Thu Jun 23, 2022 6:03 am

fun indeed!
Just to be clear for me (often dense): Are you using the freezer as a freezer or fridge?
Simple answer.. I am using the freezer as a fridge.

Complex answer..
The actual item is a top lid chest freezer of the 7 cuft or there about variety. I have an off the shelf programable cooling thermostat programmed to start cooling at anything above 44 degrees F and continue cooling until 34 degrees. The freezer power plugs in to and is controlled by this cooling thermostat which has a temperature probe that runs inside the freezer and hangs there not touching any surfaces. I didn't modify the freezer at all but installed the cooling thermostat in line and it tells the freezer when to run and when to stop. I call it a refrigerator at times based on the temperature range it is cycling in.

Realistically it probably puts the freezer in somewhat of a short cycle scenario but it doesn't seem like it is too short of a cycle as to damage components. One notable observation is there is some cooling overrun and the temp inside the box continues to cool for a short time after the call for cooling is over and the power has been interrupted.

My changed up data logging temp probe location works better. The time scale is correct and accurate to about 20 min off actual time but the temperature scale is not correct. I was surprised there were not more run cycles at night. Running time is the downslope from the peak on this circular chart.

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Re: Solar Powered refrigerator project

Post by motskyroonmatick » Thu Jun 23, 2022 7:59 pm

Token wrote:
Thu Jun 23, 2022 6:39 pm
Motsky! You’re a Mensch!!!
Thanks!
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Re: Solar Powered refrigerator project

Post by ygmir » Fri Jun 24, 2022 6:28 am

motskyroonmatick wrote:
Thu Jun 23, 2022 7:55 pm
ygmir wrote:
Thu Jun 23, 2022 6:03 am

fun indeed!
Just to be clear for me (often dense): Are you using the freezer as a freezer or fridge?
Simple answer.. I am using the freezer as a fridge.

Complex answer..
The actual item is a top lid chest freezer of the 7 cuft or there about variety. I have an off the shelf programable cooling thermostat programmed to start cooling at anything above 44 degrees F and continue cooling until 34 degrees. The freezer power plugs in to and is controlled by this cooling thermostat which has a temperature probe that runs inside the freezer and hangs there not touching any surfaces. I didn't modify the freezer at all but installed the cooling thermostat in line and it tells the freezer when to run and when to stop. I call it a refrigerator at times based on the temperature range it is cycling in.

Realistically it probably puts the freezer in somewhat of a short cycle scenario but it doesn't seem like it is too short of a cycle as to damage components. One notable observation is there is some cooling overrun and the temp inside the box continues to cool for a short time after the call for cooling is over and the power has been interrupted.

My changed up data logging temp probe location works better. The time scale is correct and accurate to about 20 min off actual time but the temperature scale is not correct. I was surprised there were not more run cycles at night. Running time is the downslope from the peak on this circular chart.

thanks so much for the explanation! Do you think it'd detrimental to the freezer, to cycle so much? Seems to me they run constantly, in normal operation? At least my 30 year old chest freezer does. It's run for years, so far anyway.
I'd wonder about overall energy use, constant run vs cycling? Understanding the load at start up and all? I could see a cool mod where it'd run as normal, and have another insulated space attached via air ducts (in and out) to circulate cool air, either by convection or a small fan, so it'd be freezer and fridge?
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Re: Solar Powered refrigerator project

Post by Token » Fri Jun 24, 2022 10:28 am

ygmir wrote:
Thu Jun 23, 2022 7:07 pm

@Token:
where does the 3 phase fit in? I'm sorta confused by that, in that I'm making single phase?
Fair admission: I don't know much about this solar/inverter/converter/battery stuff...
Enphase microinverters are by design 3-phase.

Either 208V or 220V.

When you tie them off into the main circuit you can either connect them as split-phase or full 3-phase.

They do this so they can daisy-chain the panels and lower the current per conductor so you don’t have thick copper requirements or the super high voltage of traditional string configurations.

It basically creates a 3-phase bus with up to 20 panels on it.

It’s a nifty concept.

You need to carefully check the model numbers to see if they support off-grid.

Enphase is notorious for testing the grid connection for their grid-tie parts to enforce a shutdown the moment it detects its an island. It’s basically crippleware.

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Re: Solar Powered refrigerator project

Post by ygmir » Fri Jun 24, 2022 1:14 pm

Token wrote:
Fri Jun 24, 2022 10:28 am
ygmir wrote:
Thu Jun 23, 2022 7:07 pm

@Token:
where does the 3 phase fit in? I'm sorta confused by that, in that I'm making single phase?
Fair admission: I don't know much about this solar/inverter/converter/battery stuff...
Enphase microinverters are by design 3-phase.

Either 208V or 220V.

When you tie them off into the main circuit you can either connect them as split-phase or full 3-phase.

They do this so they can daisy-chain the panels and lower the current per conductor so you don’t have thick copper requirements or the super high voltage of traditional string configurations.

It basically creates a 3-phase bus with up to 20 panels on it.

It’s a nifty concept.

You need to carefully check the model numbers to see if they support off-grid.

Enphase is notorious for testing the grid connection for their grid-tie parts to enforce a shutdown the moment it detects its an island. It’s basically crippleware.
great thanks!
well, I guess I'll just not bother with the MI's and just go with my 1500W Trace inverter. Brand new in the box, I bought it in 1999 and never even took it out. I keep all my equipment batteries on a shelf and rotate dulsfators and trickle chargers between them, so if I have to hook up fast I can just grab a couple.
thanks!
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Re: Solar Powered refrigerator project

Post by motskyroonmatick » Fri Jun 24, 2022 3:43 pm

ygmir wrote:
Fri Jun 24, 2022 6:28 am

thanks so much for the explanation! Do you think it'd detrimental to the freezer, to cycle so much? Seems to me they run constantly, in normal operation? At least my 30 year old chest freezer does. It's run for years, so far anyway.
I'd wonder about overall energy use, constant run vs cycling? Understanding the load at start up and all? I could see a cool mod where it'd run as normal, and have another insulated space attached via air ducts (in and out) to circulate cool air, either by convection or a small fan, so it'd be freezer and fridge?
Short cycling is probably only an issue when the system hasn't had enough time for the pressure to equalize on the output side of the compressor. Generally compressor refrigeration equipment has a 5 minute timer that prevents rapid restarts of the compressor and this keeps the compressor from working against a head of pressure when it starts. The downfall of interrupting the power supply is that usually that process also resets the 5 min timer. However in my trial run the length of time between restarts seems to be at minimum an hour and 45 minutes. So way more than plenty of time to let the pressures equalize and not over AMP the compressor at startup.

It is quite possible that I am using more energy in the refrigerator scenario than if it were a deep freezer. I think the temperature band in the freezer scenario is wider so there would be less startup cycles but longer run time.

As far as modifying this newer freezer... apparently the sides of the box contain coils so all modifications have to happen above the lip of the box.

Slap a Kill A Watt on that freezer and see what the consumption is. Solar stuff is in general more expensive than gas generators powering things but it's pretty satisfying to have a no inputs system once it is all put together.
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Re: Solar Powered refrigerator project

Post by motskyroonmatick » Fri Jun 24, 2022 3:58 pm

Victron has some products where you can add micro inverters to the inverter/charger 120v output and not endanger the inverter but it's expensive and for off grid just charging batteries seems to be more cost effective.
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