Using only DC appliances

[GeorgeF]

Been following some fora about solar in different countries and am amazed how they are talking about 12v systems with dc-appliances.

Many times I've been reading "get out of "the 12v box"...??? On the other hand expert's advice is not to use batteries if there is grid available. Contradictio in terminis!

OK, I am one of those "suckers" who went offgrid in a big city and my energy use is now < 400Wh per 24 hours, cause I am using only low voltage DC appliances like a projector which I connect to a TV tuner and USB speaker total < 15w @ 5v.

* Projector 2A with only USB 5v input
* TV tuner 600mAh @ 5v
* Speakers 2-3w @ 5v

Not a TV-freak myself , this setup is acceptable for me although the quality of a 10w "chicom" projector with little lumens is "ofcourse" low.

Living in a tropical country with no aircon, but if needed 12v ceiling fan and other DC fans, acceptable low voltage DC lighting and for example also 8-15w 12v brushless pump and I'm lucky to be able to live with only (filtered) rain water. Cooking with gas.

Let me ask you experts a question:
If you want to use batteries concentrate your load as low as possible. This can be achieved if you ONLY have DC-powered loads. For those "suckers" who use DC-AC inverters with huge capacity batteries, better follow the advice of Sunking (see attached screenprint ) and use only grid with genset as backup otherwise your wallet will get more holes, right??

As far as I know there is for example no AC pump which draws +/- 15watts and can lift +/- 4m which I use 1-2 hours each day to fill my water tank. For the same result you perhaps can use few minutes AC jetpump instead but I use only 50Wp panel for my "chicom" brushless pump and no inverter. I also think there are not so many people that can watch TV using max 15w only.

If you want to discuss "standard of living and comfort" in combination with solar, you are wasting your time and mine. Just use the grid and no solar solar system (with batteties) at all.

For those who think I am one of those "green guys" , forget about green. My grass is greener than those "green dreaming suckers."

Just want to share my solar experience and thoughts as an amateur in the living off-the-grid world with solar.

[organic farmer]

One of my neighbors went off-grid in the 1980s. His house is entirely 12vdc. There are motorhome dealers who stock a wide selection of 12vdc appliances to furnish a home like that.

For batteries, he uses 12vdc automobile batteries.

[bob-n]

Good stuff, George. Thank you.

Do you have any conventional wall switches for lights or other uses that are fed from 12V DC?
Do you run a full-size refrigerator/freezer from 12V DC?

Point-of-load generation and moderate power consumption are ideal. For those that are still adicted to high-power appliances and long power-line runs, this philosophy may not work as cleanly due to the need for very fat wire. That's where high-voltage distribution and high-voltage loads comes in handy.

[chrisski]

No, I don’t want to live in a 12 volt world. It is OK to have comfort in life.

If its 120 degrees out, I want to turn my AC on. If its 100 degrees out, I want to turn my AC on. I want to throw my clothes in a washer, hang them on a line to dry, and then iron them before I go to work. I don’t think there’s any such thing as a 12 volt air conditioner for my house which I would plug in with a 500 MCM or more likely much bigger cable. Same thing for the washing machine.

When I lived in the sub tropics for 14 years, never used much AC, but there were dehumidifiers and I still washed my clothes in a washing machine.

[organic farmer]

No, I don’t want to live in a 12 volt world. It is OK to have comfort in life.

I find it interesting that you associate 'comfort' with non-12vdc.

... If its 120 degrees out, I want to turn my AC on.

That sounds reasonable. However that is completely Off-topic. This thread is about living in homes wired with DC. So I am not sure why you think you can not run an A/C unit.

... If its 100 degrees out, I want to turn my AC on. I want to throw my clothes in a washer, hang them on a line to dry, and then iron them before I go to work. I don’t think there’s any such thing as a 12 volt air conditioner for my house which I would plug in with a 500 MCM or more likely much bigger cable. Same thing for the washing machine.

I think I am beginning to understand now. You think that you can not run a 120vac appliance from a 12vdc power source.

I am not sure what country you live in, but here in the United States of America we have places called Truck Stops. The big ones have a wide selection of cool stuff inside, including invertors.

Truck drivers can install any 120vac appliance that they desire inside their trucks, powered by the truck 12vdc circuits, inverted into 120vac.

[GeorgeF]

Good stuff, George. Thank you.

Do you have any conventional wall switches for lights or other uses that are fed from 12V DC?
Do you run a full-size refrigerator/freezer from 12V DC?

Some are selling here these used switches ( see pict) and I also use (marine) DC switches.

About a fridge, unfortunately no DC compressor fridge available in the area where I live. Awaiting such a fridge I m using an inefficient thermo electric fridge, only when needed. Most of the time it is off as im living on a walking distance of shops and markets.

Im lucky also that laundry is so cheap here, so we are not washing our clothes ourselves.

[chrisski]

You think that you can not run a 120vac appliance from a 12vdc power source.

12 VDC is great until you want to run something with some power behind it, then you can't. I'm not talking about taking the family camping or on a road trip, where everyone gets closer to nature by doing without modern conveniences for a day or two or if you're real brave two weeks, I'm talking about not being able to have a house that you and your spouse and your two kids can live in day after day, month after month.

I'm saying if you have an electric kettle that pulls 1700 watts with 120 VAC. That can be plugged into the wall with a standard 15 amp plug, because it is pulling between 14 amps and 15 amps, what that plug is rated for. If you try to run the same kettle off DC, where you are adding 1.7 litres of water, and design it to run off DC, it will still require 1700 watts to heat the water just as quickly. This is 140 amps. Once you need to move that much amperage through a wire, you need to get thick 2/0 to 750 MCM cables, depending on your margin of safety.

I used to think it was just wiring, but its more than that. With those thick cables, you've now lost the ability to plug it in, the appliance will have to be bolted in; something I don't want to do when I iron clothes. Also, at that amperage and DC, arcing becomes a real hazzard. That is why the bigger DC switches and circuit breakers become so expensive compared to DC. Its more than just a supply and demand thing for these switches thatmakes them expensive, its the engineering going into these switches so that they can deal with this arcing.

There's a reason DC lost to AC in the race between Tesla and Edison, and its more than just Tesla was better at marketing.

As you go up in DC voltage, the wiring becomes skinnier and is less of a problem, but the arcing problem is still there.

You could plug a truck stop inverter in, but again, you won't be putting out a lot of power or doing laundry with those. Perhaps inflating an air mattress, but not through the accessory port, that won't pull enough power, but you can hook it to a battery.

[GeorgeF]

No, I don’t want to live in a 12 volt world. It is OK to have comfort in life.

If its 120 degrees out, I want to turn my AC on. If its 100 degrees out, I want to turn my AC on.......

You run an airconditioning, fridge and other heavy loads on batteries also during the evenings?? Mr Peukert will arise from his grave and will smile at you.

I was considering to run a 260W aircon for during the day only but reconsider it. Cause perhaps you get used to it and want to try to run it till morning. I better connect myself to the grid then.

[chrisski]

You run an airconditioning, fridge and other heavy loads on batteries also during the evenings?? Mr Peukert will arise from his grave and will smile at you.

I was considering to run a 260W aircon for during the day only but reconsider it. Cause perhaps you get used to it and want to try to run it till morning. I better connect myself to the grid then.

Fridge and AC etc off batteries being a bad idea, that's the point I'm trying to make.

A 260 watt air conditioner may cool down a closet in Arizona during a summer night.

It's not that you can't run AC off solar, at least not AC to cool your family down, its that you can't do it off 12 volts.

[organic farmer]

... You could plug a truck stop inverter in, but again, you won't be putting out a lot of power or doing laundry with those. Perhaps inflating an air mattress, but not through the accessory port, that won't pull enough power, but you can hook it to a battery.

One invertor is plenty for an A/C unit. Or for a washing machine, Or a refrigerator.

Within the solar power community, you will see that homes that were wired for 12vdc often have one invertor for each large appliance.

[chrisski]

Within the solar power community, you will see that homes that were wired for 12vdc often have one invertor for each large appliance.

I would think anyone that has ever installed three 2000 watt inverts off a 12 volt system, one each to run the Washing Machine, the fridge, and then the air conditioner off 12 volts would wish they went with 48 volts instead.

I am relatively new to solar, but a 12 volt house, not a mini house for one person, or a RV to go weekend camping, is just a terrible idea.

[organic farmer]

I would think anyone that has ever installed three 2000 watt inverts off a 12 volt system, one each to run the Washing Machine, the fridge, and then the air conditioner off 12 volts would wish they went with 48 volts instead.

I am relatively new to solar, but a 12 volt house, not a mini house for one person, or a RV to go weekend camping, is just a terrible idea.

Solar power is not a brand new idea. People have been powering homes from solar power for decades.

I certainly agree that there are more ideal products to use given the technology of 2020.

I find it interesting to visit folks who have been using solar power for decades and seeing how they addressed the same issues.

[SunEagle]

Solar power is not a brand new idea. People have been powering homes from solar power for decades.

I certainly agree that there are more ideal products to use given the technology of 2020.

I find it interesting to visit folks who have been using solar power for decades and seeing how they addressed the same issues.

IMO most of those people that power all of their loads from solar and 12V system either live in cooler climates or have a very low energy life style. For a lot of the other people that depend on AC or larger load items living on a 12V battery system can be challenging or very expensive compared to living on the grid.

It falls to what people like and what they can live with.

[organic farmer]

When I was shopping for land to homestead here in Maine, many of the properties do not have ready access to grid power. It is common that you might need to get a power easement and run poles 10 to 20 miles to reach a given homestead site. With every wind storm, trees blow down. Trees blowing down are rough on power lines. A private 10-mile power line can be expensive to maintain when trees keep pulling it down. I ended up buying land that already had grid access, but our grid goes down frequently.

Which leads to either using a generator and paying up to $150 a month for fuel, or solar / wind power.

Either way it is still cheaper than living in a city.

[SunEagle]

When I was shopping for land to homestead here in Maine, many of the properties do not have ready access to grid power. It is common that you might need to get a power easement and run poles 10 to 20 miles to reach a given homestead site. With every wind storm, trees blow down. Trees blowing down are rough on power lines. A private 10-mile power line can be expensive to maintain when trees keep pulling it down. I ended up buying land that already had grid access, but our grid goes down frequently.

Which leads to either using a generator and paying up to $150 a month for fuel, or solar / wind power.

Either way it is still cheaper than living in a city.

And I believe you have found the best direction to go when it comes to power for your home.

What I am saying is that most people are much closer to the grid and will have to pay a lot less then it costs to install a solar/battery system.

Again each person needs to do the math to see what they want and what they can afford.