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My solar setup example and choosing appliances- Freezer

 
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My partner and I have spent a couple years building an off-grid house in wisconsin and we are moving in next week. I just setup the solar and it's working great so far. I've attached my wiring diagram in case anyone is interested. Note that we actually have a 250A battery to inverter breaker, not 175. Fat cable is 2/0, unlabeled is 4awg (except the small looking cable going from positive bus bar to 250 breaker- I doubled up 4awg in lieu of a 2/0 spot on that busbar.)  Panels are bifacial about 450 watts max each. Inverter is Victron Multiplus 2000W. Three 206 Ah 12V SOK Li Iron batteries in parallel. 2 MPPT 150/100 victron controllers.

We have an old crappy freezer that I don't want to bring on site. I'm choosing one now. I've gone through the older permies posts on freezer/refridgerators to get some ideas. We do plan on having an ice box/house and also using a cold room most of the year for refrigeration, we will start out continuing to use the big cooler we've used for a couple years. Maybe use a fridge in summer when extra sun. I'm about to purchase a freezer asap and here is what I've found.

DC options:
Most DC options are mindbendingly expensive and have a 1 year warranty and are not really locally repairable which makes me scoff at them initially. It's nice to turn off the inverter, but we will do that anyway at night even with an AC freezer- keep it full and inside, eventually in root cellar, it won't defrost overnight. And I'll get a cheap backup inverter. I could go smaller on the freezer and keep a bigger one off site but these are my initial options. I may be wrong so I'm wondering:
-Are DC freezers repairable or their parts replaceable? Does anyone have experience with this for, say, the Sundanzer brand? This might change my mind
Sundanzer DCRF384:
-13 c ft
-about 63-70 Ah/day
$1900
not available at moment (big back order)

AC  options
I read here that Danby freezers are pretty decent. I'm looking at Danby 11 cu ft freezer
$700
https://www.homedepot.com/p/Danby-11-0-cu-ft-Chest-Freezer-in-White-DCFM110B1WDB/301650442
Pros are that it would be locally repairable, cheaper, better warranty, about as much energy, and available. Cons - a bit smaller and needs an inverter.
11 c ft
55-60 Ah/day

Thoughts anyone? We've spent the initial cash on a decent solar system, so why not use the AC and turn off at night? Am I wrong about repairability? As I mentioned the inverter is pretty efficient and we have oversized the batteries for our needs. This would be our largest year round appliance.

Thank you!
-Courtney
wiring-diagram.jpeg
[Thumbnail for wiring-diagram.jpeg]
 
steward
Posts: 1708
Location: Coastal Salish Sea area, British Columbia
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It looks like you have 2 charge controllers because the Victron 150/100 can only handle 1450w at 12VDC. One question i have is do you intend to use the DC power to power anything? Or would going to 24v help? I say this because it would mean you only need one CC for your set up.

I wish i had a better answer in regards to the DC/AC Freezer. All the points you bring up are valid. We decided on a AC freezer because our neighbour who has been a solar consultant for 30 years said it was cheaper.

So what you could do is buy the 700$ ac freezer and get another battery/solar panels/etc to make up what you would have spent on the DC freezer. As far as i know the DC freezer last a long time. I am really not sure how long our ac freezer will last. We can also probably go to home depot when this one dies and get another freezer in almost the same day if needed. Not sure if that can be done with a DC freezer( it might need to be ordered)



So yes we initially tried to run the freezer all night and ended up consuming way to much power. We now shut if off overnight for about 10 hours. maybe less. Our freezer is located outside in our shed. It seems to work fine.

One thing i have heard of is you can use an AC programmable timer and run the the freezer. Program it to come on every hour for 10 minutes( you would need to experiment) That way the led display isn't always on. Having the programmable timer would shut the display off.

My suggestion would be to get a freezer which doesn't have the display.


I also want to say nice setup. The drawing is great. Those batteries have some nice reviews.




 
pollinator
Posts: 631
Location: North central Ontario
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Courtney Jarman wrote:My partner and I have spent a couple years building an off-grid house in wisconsin and we are moving in next week. I just setup the solar and it's working great so far. I've attached my wiring diagram in case anyone is interested. Note that we actually have a 250A battery to inverter breaker, not 175. Fat cable is 2/0, unlabeled is 4awg (except the small looking cable going from positive bus bar to 250 breaker- I doubled up 4awg in lieu of a 2/0 spot on that busbar.)  Panels are bifacial about 450 watts max each. Inverter is Victron Multiplus 2000W. Three 206 Ah 12V SOK Li Iron batteries in parallel. 2 MPPT 150/100 victron controllers.

We have an old crappy freezer that I don't want to bring on site. I'm choosing one now. I've gone through the older permies posts on freezer/refridgerators to get some ideas. We do plan on having an ice box/house and also using a cold room most of the year for refrigeration, we will start out continuing to use the big cooler we've used for a couple years. Maybe use a fridge in summer when extra sun. I'm about to purchase a freezer asap and here is what I've found.

DC options:
Most DC options are mindbendingly expensive and have a 1 year warranty and are not really locally repairable which makes me scoff at them initially. It's nice to turn off the inverter, but we will do that anyway at night even with an AC freezer- keep it full and inside, eventually in root cellar, it won't defrost overnight. And I'll get a cheap backup inverter. I could go smaller on the freezer and keep a bigger one off site but these are my initial options. I may be wrong so I'm wondering:
-Are DC freezers repairable or their parts replaceable? Does anyone have experience with this for, say, the Sundanzer brand? This might change my mind
Sundanzer DCRF384:
-13 c ft
-about 63-70 Ah/day
$1900
not available at moment (big back order)

AC  options
I read here that Danby freezers are pretty decent. I'm looking at Danby 11 cu ft freezer
$700
https://www.homedepot.com/p/Danby-11-0-cu-ft-Chest-Freezer-in-White-DCFM110B1WDB/301650442
Pros are that it would be locally repairable, cheaper, better warranty, about as much energy, and available. Cons - a bit smaller and needs an inverter.
11 c ft
55-60 Ah/day

Thoughts anyone? We've spent the initial cash on a decent solar system, so why not use the AC and turn off at night? Am I wrong about repairability? As I mentioned the inverter is pretty efficient and we have oversized the batteries for our needs. This would be our largest year round appliance.

Thank you!
-Courtney


It is always nice when someone does their homework ...
My first house was fully off grid with dedicated DC wiring to certain areas of the house. That was the understood logic 20 years ago but about 15 years ago the off grid world changed. When the price of panels started dropping the era of the 12 volt house with custom wiring and 12 volt appliances started to die out. The electrical code caught up as well making all that custom stuff either illegal or an insurance problem. That is an opinion of course but the power math and financial math is pretty sound. I'm not saying that a 12 volt only solution does not work and it does make for a simpler setup just that they are almost solely used on trailers and very small houses now.
For your case the sleep mode on your inverter is only 3 watts so using an AC freezer and not turning it off would only give you a 72 Whr deficit over a DC freezer.  So small negative there but it still comes in lower overall. Then there is the fact that the Danby you listed is using the r600 refrigerant where as the sundanzer is still using the 134a (now two generations out of date) which will cut energy usage on the Danby by at least 10 percent over the sundanzer.  As you also pointed out cost is less than half, better warranty and fixable by a regular appliance person. From past experience I can tell you very few techs will touch the sundanzer.
To me the choice is clear. Others will disagree. Having gone both ways I long ago switched over to an all ac house. The new house I'm building now will be a grid connected system with battery backup so I've fully embraced the new tech.
As an asside those same chest freezers can be converted to a fridge using either a mechanical thermostat or a beer keg add on refrigerator thermostat. They will use about half of the power consumption as the freezer setting and less that half of the power as a same sized upright fridge. Both the freezer and fridge  can be located in the cold room as their compressors can take the cold well unlike fridges.
Cheers and congrats on your new house.
David
 
pollinator
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We put timers in place on fridge and freezer, and both are off at least 8 hours overnight, when nobody is opening them. We also move a few frozen water bottles between the two for that period. The freezer never budges. The Fridge temp rarely rises above 40 degrees or so on the overnight period.

We hope to replace that fridge entirely with a freezer-into-fridge in the future, with a kitchen remodel that frees up horizontal space for the freezer design.

These days, 1-year or less warranties = disposable (and not worthy of your money). If not 2- or 3-year or longer, walk away and/or find an alternative. A toaster or coffee pot used to be the upper end of disposable items, now it's high-end appliances and such.

I never could swallow the DC premium on appliances ... but, the homestead is spreading out, so I'm planning a parallel, all low-voltage wiring system for night lighting only, always on (w/ timers) such that even on moonless nights, there's low levels of light. Fully solar, but independent of house AC or it's current off-grid system. Saves toes ...
 
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Courtney Jarman wrote:We do plan on having an ice box/house and also using a cold room most of the year for refrigeration, we will start out continuing to use the big cooler we've used for a couple years. Maybe use a fridge in summer when extra sun.



I have no advice for you about what kind of appliance to buy, but I have good experience with placement of the appliance. I designed my house to be passive solar heated, with the rooms we use most along the south face of the house. The north side of the house is the thermal buffer zone containing the corridor, stairs, composting toilet, and three storerooms. They get very chilly in winter, but don't drop quite to freezing.

The pantry (storeroom) along the north side of the kitchen stays below 6˚C (42F) for several months of fall, winter and spring, and I placed the fridge in there. It's a standard fridge-below-and-freezer-above model, rated 4 out of 5 stars for efficiency in the Indian rating system. In winter it hardly draws any power at all: I think almost none for the fridge, and some for the freezer. In winter, it's very convenient to have such a chilly pantry. We can put things on the pantry shelves or floor instead of inside the fridge.

In winter we also put hot items on the floor of the cold back corridor to cool before putting them in the fridge, such as 2 or 3 liters of boiled fresh milk, or a big pot of curry, dal or bone broth.

Even in summer, when there's a power outage for up to about ten or twelve hours (very common in my region), the stuff in the freezer doesn't seem to thaw or get much frost. If I'd special-ordered the five-star efficiency model instead of taking the in-stock four-star model, this would probably be better. I'm sure in the US you can get better.
 
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I would second the suggestion to abandon 12V and go to at least 24V for your system.  I would not spend any extra money on 12V DC appliances, but use the money to invest in more panels and another battery.  Instead of three 12V batteries in parallel, get a fourth battery and wire them for 24V as 2S2P.  By upping the charging voltage and halving the amperage, you can build the system with one controller instead of two.  I've got my homestead workshop running with a 24V system, and it performs perfectly.  Alternatively, you could take that extra battery and wire the whole bank into a 48V system, which is what I have for the cabin.  That can run my 240VAC well-pump on my 48V inverter.  

Once you get into 24V, the quality of components goes way up.  You can get whole-house hard-wired inverters at 24V that just aren't there for 12V.  I have Schneider's 4024 Conext that has lots of extra bells and whistles.  It puts out both 120V and 240V split-phase AC, and has a built-in generator charging circuit with it's own transfer switch.  So, you can charge the batteries directly from generator output.  Also look at quality sine-wave inverters from Magnum, Outback, and Samlex.  Both my systems run 24/7, with the inverters never being turned off.  I just compensate for the additional power consumed by the inverters with another panel or two.

Those are nice panels, but if you want to upgrade your watts later, you don't have to buy the matching panels.  Just make sure the panel string you have is the same voltage (within 5%), and just wire the new strings in parallel side by side in your combiner.  I shop for panels on Craigslist with local pickup and I've consistently gotten 3-4W/$ shopping locally.  They are amongst the highest quality panels I've got.

If you have some special 12VDC device that you really want to keep, like your favorate stereo, you can get a 24VDC to 12VDC converter cheap.  They are about 15-16$ on Ebay right now.
 
pollinator
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Ive had very good results with 24 volt residential energy systems and AC appliances. My friend added insulation to his AC fridge which helped a lot. AC appliances have gotten more efficient in general. I wouldn’t spend much time, effort, or cash on Dc appliances. I agree with a Michael that you could add to your system and turn it into a 24 volt system. You would have no problem selling the Victron. Lots of folks are building 12 volt systems for mobile use. If you require huge amounts of power then 48 volts is likely the route to go. After doing several off grid systems My next system might be on grid (grid intertie). Ive found large amount of the solar energy is water with my off grid systems which could be used. But that’s partly because I keep moving around d so much that I haven’t gotten around to installing a dump load. Theoretically one can just heat water with the extra power. A dump load is the usual DC appliance but it can also be a AC appliance. Congrats on your new home.
 
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