DC-Living, all DC appliances for new Tinyhouse -Offgrid project?

[HalfBaked]

I use my 120v coffee maker as a pour over all the time. Boil water with propane stove.

Even on 120v I will let the coffee maker fill the pouch. Let it steep 5 or 10 mins and turn the power back on. Guy on YouTube mentioned that trick for more flavorful coffee.

You are sorta describing a French press, which makes the best coffee. Even cheap coffee tastes best from one.

You can also take your coffee game up a notch and roast your own on the stove using a popcorn popper with a crank handle. It's the best coffee you can make, takes 10 minutes, and is cheaper than Folgers.

A light roast has a lot more caffeine as well. You will only need 1 cup/day.

 

[wopachop]

Id love a 700 watt induction cooker. most are rated for more than that. or an electric kettle in the 700 watt range.

Those exist. Some have a switch so it cant go over 700w. Most use a power level. Often Level 5 is simply 500w.
I bought an induction cooker hoping to use it with a 400w inverter to slow cook things.
Wasnt happy. Even set to power level 1 with a claimed 100w draw it would pull more like 400w in quick spikes.
I tested it on shore power so it wasnt related to the cheap little inverter.

 

[AntronX]

I would wire house lights on DC to avoid LED light flicker from the inverter. 24Vdc is about the highest voltage that standard 120Vac light switches will reliably switch off without arc. For water heating use 50 gal tank water heater with 48V DC element = free 3 - 6 kWh/day "battery" in the form of hot water. You can have 48V > 19V, 12V step down converter to power computers, network gear, electronics to keep them on steady power source. Everything else can run on multiple cheap inverters that you can optimize for idle load. For example the water well pump does not need the inverter to run 24/7. You can have a controller circuit automatically turn on the inverter when the pump switches on. Multiple smaller inverters also increases redundancy. Go with cheaper inverter like Growatt spf5000es + autotransformer.

 

[eXodus]

While the compressors are variable speed they still have a range of outputs they operate in, and as you go up in size the lowest output they can operate also goes up.

Good point, I have to lookup what to lower range is.

My research showed bifacial is not cost/benefit realistic at all...at least in my area

I have used panel supplier in my area - and they sometimes have stacks of Bifacial, at decent pricing. For Bifacial I'm figuring - I don't need roof decking, I wouldn't want to look at the underside of a regular panel, but bifacial are beautiful.

. For example the water well pump does not need the inverter to run 24/7.

The 48V well pumps are much cheaper then the 120V or 240V pumps. There is no reason to have them on an inverter. I can literally buy 2x 48V pumps for less then one 120V pump. Further depending where my well will be - it might not be feasible to run wire from the house. It might be small dedicated system.

You could also go with a mixed system. Make the lighting DC, but put the AC appliances on an inverter that you turn off at night. You could use a DC refrigerator or you could use an inverter dedicated to the fridge that's just large enough for that load only.

This is probably a good solution. A mixed system - all DC for stuff which runs constant.

DC-Fridge,
DC-Heatpump
DC-Water heater

Small inverter for daily intermitted AC load and convenience items. I mean the inverters have some sort of low power mode where they turn off their output.

 

[eXodus]

You could also go with a mixed system. Make the lighting DC, but put the AC appliances on an inverter that you turn off at night. You could use a DC refrigerator or you could use an inverter dedicated to the fridge that's just large enough for that load only.

The 12V DC fridge is barely more expensive then a regular one and a ridiculous amount more efficient.

For the same size like the DC takes 500-600wh vs 1-1.3kWh / day and this is AC input to the fridge - that is not what is going into the inverter. Lets say the inverter is 90% efficient - we are looking at almost 3X the power usage. Meaning - I need one 1kWh more storage/day.

1kWh of battery is about $300 installed. The 12V fridge is only $100 more expensive then the regular fridge. So It already makes sense even before factoring in Solar panels to produce this additional 1kWh/day

 

[eXodus]

I spent 3 years planning our 100% off-grid glamstead...AC house wiring and appliances were hands down the right way to go. And 4 years living with it has proven it. The DC well pump is a completely separate system and fantastic!!

do you have some of those plans or final product to share? Would love to learn from someone who already went through the experience. I'm still in the planning stages and want to start building next spring.

 

[yodamota]

yea i think the hybrid will work the best given how the world currently works.

I do think a DC fridge/freezer is a much better solution. Our AC freezer is the number one reason our inverter shuts off in the winter. Its pulling around 40 amps to start the compressor, which drops the battery voltage below the low voltage cutoff of our inverter. Plus in order for the freezer to function the inverter needs to be "on" which consumes 25w per hour. This need to have the inverter on for the freezer means the already 1kwh per day turns into 1.5kwh. This is for our 5.1cuft freezer from costco.

 

[rhino]

The 12V DC fridge is barely more expensive then a regular one and a ridiculous amount more efficient.

Do you have links to 12V DC fridge that shows this? I once looked as a DC chest freezer and even though it was more efficient (a lot of it was because it had thicker insulation not because it was DC) I found out the quality was crap.

I would wire house lights on DC to avoid LED light flicker from the inverter.

That is only because of cheap LED lights and/or cheap inverters. Never had issues with LED lights flickering on low frequency inverters.

 

[yodamota]

Do you have links to 12V DC fridge that shows this? I once looked as a DC chest freezer and even though it was more efficient (a lot of it was because it had thicker insulation not because it was DC) I found out the quality was crap.

this part blows my mind. why not insulate AC freezers the same as DC?

 

[AntronX]

That is only because of cheap LED lights and/or cheap inverters. Never had issues with LED lights flickering on low frequency inverters.

My not cheap LED filament lights from Lowes do flicker when my Weller soldering station gets to temp setpoint powered from Victron inverter.

 

[rhino]

My not cheap LED filament lights from Lowes do flicker when my Weller soldering station gets to temp setpoint powered from Victron inverter.

I still think they are because of the LED lights and wish there was some list of LEDs that don't have this issue. What is funny is I even see "non flickering" LED lights listed on Amazon now.

 

[eXodus]

Do you have links to 12V DC fridge that shows this? I once looked as a DC chest freezer and even though it was more efficient (a lot of it was because it had thicker insulation not because it was DC) I found out the quality was crap.

SunStar Solar / DC Refrigerator 16CU ST-16RF (BLACK)

SunStar 16CU Solar/DC Refrigerator (Black) Designed specifically for off-grid use, the SunStar 16CU Solar/DC refrigerator is an industry leader in this model category, the largest of its kind, and 100% Made in the USA. Featuring a dual independent compressor + dual thermostat cooling system (one...

www.thecabindepot.com

Energy Consumption

Configuration: Top compartment and bottom compartment both set to refrigeration 38F (+3C)

• Average room temperature 70F (+21C) = 229Wh per 24hrs
• Average room temperature 90F (+32C) = 462Wh per 24hrs

Configuration: Top compartment set to freezer 0F (-18C) and bottom compartment set to refrigeration 38F (+3C)

• Average room temperature 70F (+21C) = 415Wh per 24hrs
• Average room temperature 90F (+32C) = 728Wh per 24hrs

They sell clones of the SunStar for much less, with similar power numbers. I don't know about the quality in person

 

[AntronX]

That's very good efficiency. My 120V house fridge uses 3.6 kWh per day on average.

 

[rhino]

SunStar Solar / DC Refrigerator 16CU ST-16RF (BLACK)

SunStar 16CU Solar/DC Refrigerator (Black) Designed specifically for off-grid use, the SunStar 16CU Solar/DC refrigerator is an industry leader in this model category, the largest of its kind, and 100% Made in the USA. Featuring a dual independent compressor + dual thermostat cooling system (one...

www.thecabindepot.com

Energy Consumption

Configuration: Top compartment and bottom compartment both set to refrigeration 38F (+3C)

• Average room temperature 70F (+21C) = 229Wh per 24hrs
• Average room temperature 90F (+32C) = 462Wh per 24hrs

Configuration: Top compartment set to freezer 0F (-18C) and bottom compartment set to refrigeration 38F (+3C)

• Average room temperature 70F (+21C) = 415Wh per 24hrs
• Average room temperature 90F (+32C) = 728Wh per 24hrs

It does look like in that case the insulation is at least twice as thick as a normal AC fridge? If so that is as I've noticed with a DC chest freezer that the performance was not because it was DC but because it had thicker insulation.

 

[rhino]

The chest freezer I had looked at was from https://sundanzer.com/ but after further research had read a lot of people have issues with the coils disintegrating.

 

[chrisski]

I had wanted to go all DC when I started my solar build, but decided AC was the way to go, just like nearly everyone before me decided.

Then I realized high wattage DC appliances were not available, or poor selection where I'd be the first on the block to have it.

I do think that DC high wattage DC never took off for home use because it is just too dangerous, especially with arcing, and second when going through the skin. DC switches are built so much thicker and bigger to avoid the arc that happens. A 48 volt Air conditioner takes two up to four times the current to run the same wattage as an 120 VAC or 240 VAC AC. More arcing than just more expensive wires. THose high amperage high AIC fuses get expensive also.

 

[eXodus]

It does look like in that case the insulation is at least twice as thick as a normal AC fridge? If so that is as I've noticed with a DC chest freezer that the performance was not because it was DC but because it had thicker insulation.

yes most DC fridges are better insulated. Probably because the Manufacturer know that their customer is Off-Grid and looks for a efficient appliances.

While most AC-Appliances - the regular consumer couldn't care less about energy usage when it has shiny stainless steel.

More arcing than just more expensive wires.

with a DC variable speed compressor on the heatpump you don't have any arcing, it's a PWM controller. No stupid on-off relay like a regular compressor has.

The DC-Fridge has 5A draw at 12V - that's minimum arcing in the relay, should last a very long time.

 

[Jacob89]

with a DC variable speed compressor on the heatpump you don't have any arcing, it's a PWM controller. No stupid on-off relay like a regular compressor has.

The DC-Fridge has 5A draw at 12V - that's minimum arcing in the relay, should last a very long time.

The arcing you have to worry about is if/when there is a fault in the unit itself or in the wiring. You need to make sure you have fuses or circuit breakers capable of dealing with that. Certainly very possible, just not as cheap and easy to clear a DC fault as with AC.

 

[OzSolar]

The chest freezer I had looked at was from https://sundanzer.com/ but after further research had read a lot of people have issues with the coils disintegrating.

I've had two Sundanzers (one fridge and one freezer), neither lasted 5 years and the fridge was a mold factory since it wasn't self defrosting. (there's something no one talks about)

Are we comparing apples to apples? All of the "super efficient" DC fridges I've been around aren't self defrosting. In humid climates they easily get moldy in the fridge compartment and build up ice in the freezer. Here's a quick read on why you sometimes notice the sides of your regular fridge are warm. I've heard that 50% of standard fridges energy (KWH)'s is from is self defrosting.

The other one that people loved many years ago was a Sunfrost but they are long gone now last I heard. Crazy expensive and honestly I always thought they were poorly built. Fit and finish were terrible and they too also prone to get moldy. Here's thread on it.

FWIW: The first fridge might be DC but when it fails you'll be replacing it with an AC one because you'll be done with it's poor quality and lack of convenience

 

[AHTrimble]

do you have some of those plans or final product to share? Would love to learn from someone who already went through the experience. I'm still in the planning stages and want to start building next spring.

What plans are you looking for?
I wired the house as any standard AC system would look like.
The appliances were all standard, albeit high-efficiency, units.