cooking off grid

sgtalexmom · August 2011

hello all. i've been lurking around here for a few months, learning and planning

i'd like some ideas on what you are using to cook off grid.

i don't need an oven. a single burner of some sort will suffice.

i'd love to go induction (fast but watt-hog!) is electric cooking really out of reach?

SCharles · August 2011

Re: cooking off grid

I took a small propane range [very small, from a mobile home] and cut off the top and installed that in my counter. I had to plug the ports that had gone to the oven/broiler. That gave me a four-burner stove I run off propane. Winters we have a wood-burning range with two ovens. It also heats that part of the house, so it is going most days and then our propane use is very little.

I tried to figure a way to run an elec. stovetop [or even a burner or two] to avoid propane, but we are solar electric and there is no way to do it within any reason. Living here full time, we use maybe 30 gal propane a year. There are only two of us, might be more use if more occupants....

zozomike · August 2011

Re: cooking off grid

Ive got 2 Max Burton induction cooktops that cause me no trouble, they seem to draw considerably less than advertised, and generally need to be used at level 2 or things will quickly overheat. They are efficient because cooking is FAST. Im soon adding a solar oven, I'm all solar here. I have a 1970 watt system and 12 batts. Don't know your resources. I can bring a quart to full boil in about 3 min, ( level 5) using 1100 watts. Since the cooktop is cool I often use heat retention, like a towel over the lid when cooking longer term items.
Michael

sgtalexmom · August 2011

Re: cooking off grid

zozomike wrote: »

Ive got 2 Max Burton induction cooktops that cause me no trouble, they seem to draw considerably less than advertised, and generally need to be used at level 2 or things will quickly overheat. They are efficient because cooking is FAST. Im soon adding a solar oven, I'm all solar here. I have a 1970 watt system and 12 batts. Don't know your resources. I can bring a quart to full boil in about 3 min, ( level 5) using 1100 watts. Since the cooktop is cool I often use heat retention, like a towel over the lid when cooking longer term items.
Michael

my "resources" aren't set yet

i'm in charge of appliances, etc., as we factor out what our system will need to be. i would LOVE to use a single induction top.

could you give me a model number?

if used 15 mins a day or less, (my average cooking times on my stovetop) this just might work!

Photowhit · August 2011

Re: cooking off grid

There are a few threads on cooking, It's difficult on solar, I have a reasonable large array for most of the year other than summer when I run an AC, My fork lift battery arrives in the morning!, but right now I even shut down my fridge for the extra hour and a half of Air...(I currently only have some almost 6 year old golf cart batteries)

The rest of the year I can run lots of table top devices when the sun is shining. When the sun isn't shining I run an microwave(900watts continuos?) and a rice cooker (300 watts not sure about the duty cycle). When the suns out I run a Foreman grill (770-840watts 50-60% duty cycle once warmed up) Cooks fast,I like the quality off of the grill, there is a learning cycle to the cleaning of it) I also use a toaster oven (1300-1500watts, duty cycle varies a lot with ambient temperatures, but no more than 60% once warmed up.) I have a hot plate, but rarely use it. I think it's 1200 watts.

I also has a gas burner and toaster oven(Coleman) but the oven is nearly impossible to regulate.

icarus · August 2011

Re: cooking off grid

IMHO, a propane range, or even a camp stove will, over the course of a year consume perhaps 60 gallons of propane (WAG) (We use 12 gallons a month, for stove, hot water and fridge averaged over the year)

A simple, standing pilot 24" gas (L/P) range is ~$400, or you can buy a small RV range for a lot less, especially if you look in a used RV wrecking yard. For my money, the convienence of having a real stove, without the expense and trouble of trying to use it off an off grid electrical system is well worth the price. We use a stove top MR Coffee maker, and even a Propane toaster. To do that all off the PV would entail a much bigger, much more expensive system. IMHO, KISS.

Tony

Photowhit · August 2011

Re: cooking off grid

For us in the states, a Gallon of propane equals @4.2lbs.

Beware of propane sold in cages outside Lowes, or the stop 'n shop down the road, typically they only put 15lbs in a 20lb tank!!! Always cheaper to buy from a wholesaler (I'll change this if someone knows a wholesaler selling for higher) For example, our camp store sells 15lbs in a 20lb tank for $21, I get a 20lb refill for $13 - $16 for a 30lb tank.

BB. · August 2011

Re: cooking off grid

Frankly, I only use the caged propane (yearning to be free

) when my tanks expire (need retesting).

And, I have been told by others that people are not even checking for dates on tanks anyways...

-Bill

Photowhit · August 2011

Re: cooking off grid

I think part of that is that the new valves are just starting to expire this year, so if it had a new valve it was OK, I admit I do the same thing, I have 1 12/99 tank I need to swap this year, and I'd love to get a couple 30lb tanks after loaning a half full 20lb tank to an outage worker he left me a 30lb tank, and I discovered how much cheaper and I think longer lasting, perhaps the 20lb leave some in when there is to little pressure for the valve, I've never compared to the par weight though.

waynefromnscanada · August 2011

Re: cooking off grid

Photowhit wrote: »

perhaps the 20lb leave some in when there is to little pressure for the valve.

Would depend on the temperature of the remaining liquid propane. As the propane is uses up, there is of course less liquid to boil off vapor, thus the remaining liquid, like a refrigerant, cools faster, and if used up fast enough, will actually cause frost to form on the outside parts of the cylinder that have liquid contacting the inside. At approx minus 42*, the pressure above the liquid propane is reduced to zero, thus none comes out, even if there were an open hole in the cylinder. Slow down the consumption so the liquid propane doesn't get too chilled, and you'll get to use it all.

mike95490 · August 2011

Re: cooking off grid

While at my off grid site, I boil water in a 1.5 liter electric kettle, in the afternoon, while the sun is still on the array, and the batteries are full. I store it in a vacuum air pump pot, and have hot water in the AM. I also have an induction hotplate, which puts 95% of the power into the pan, and not radiated heat, even more efficient than a microwave that wastes about 30-50% of the consumed power into cooling the magnatron tube.
I got my hot plate from amazon

BB. · August 2011

Re: cooking off grid

More or less, you would should size your battery bank to the maximum load. At a minimum (say 12 volt battery bank 1,100 watt input induction hot plate, 85% efficient inverter, 10% maximum sustained load):

1,100 watts * 1/0.85 eff inverter * 1/12 volts * 1/0.10 battery load = 1,078 AH minimum for 12 volt battery bank...

You could go as high as 13% of rated battery bank capacity (equivalent of 8 hour discharge on a forklift battery)--would make the battery bank a bit smaller.

A 1,078 AH 12 volt battery bank is pretty good sized (~10x 6volt 225 AH "golf cart" batteries).

The minimum sized array assuming 10% rate of charge (5%-13% range recommended), 0.77 derating, for 10x 6volt @ 225 AH batteries would be:

10x * 6 volts * 225 AH * 1/0.77 charging derating * 0.10 rate of charge = 1,753 watt solar panel (nominal)

The above does not take into account the total amount of Amp*Hours or Watt*Hours you use per day... But assuming 4 hours minimum sun 9 months of the year:

1,753 Watts * 0.52 system derating * 4 hours of sun per day = 3,646 WH per day
3,646 WH per day * 1/12 volt battery bank = 305 AH per day @ 12 volts

That is a pretty good sized system (~109+ kWH per month 6-9 months of the year), and you might want to consider a 24 volt (minimum) system (good for ~2,400 watts peak).

-Bill

john p · August 2011

Re: cooking off grid

aw shucks you guys all wimps,, Real men cook with a oxy torch..;)

petertearai · August 2011

Re: cooking off grid

Victron has some interesting white papers.This one mentions induction cooking afloat.
http://www.victronenergy.com/upload/documents/ElectricityonBoard_rev8_july2004.pdf

sgtalexmom · August 2011

Re: cooking off grid

thanks for all the info!

so far, it looks like we'll have enough roof space for 5-6 325 watt panels.

we'll have
6 LED light fixtures
Sun Danzer 4 cubic foot fridge
the underfloor radiant heat system
sanyo mini split ac (to be ran at the 300 setting several hours daily)
fan for composte toilet (if we go that direction)
the single burner induction cooktop
we'll also need to be able to recharge the mac laptop, kindle, and cell phone...although i've heard it uses less power to just keep it plugged in
blow dryer (lots of power, i know, but only for minutes a day)

i'm new to solar. we want to do it right. just gathering our "needs" list

if it is more advantageous to go 24 (or 48?) volt, we will. we should have 5 hours of available sun (northern illinois). we want enough supply to go 3-4 days with no sun

lots to think about. i'm reading all the posts i can on this forum!

Cariboocoot · August 2011

Re: cooking off grid

Just taking a glance at your load list ... underfloor heating? Blow dryer? A/C?

I think you better start adding up the Watts and Watt hours. It's going to be big.

sgtalexmom · August 2011

Re: cooking off grid

Cariboocoot wrote: »

Just taking a glance at your load list ... underfloor heating? Blow dryer? A/C?

I think you better start adding up the Watts and Watt hours. It's going to be big.

from what i've read here on the forums the ac system is doable at the 300 setting for a few hours

the underfloor heating is a direction we'd like to go...it is low watt/low volt.
we are building with the new thermal mass wall drywall on top of 6" walls (sips), etc. which will reduce our heat in summer and store part of radiant heat in winter. (or so they say) over 73F it draws in heat, under it releases it.

but i've also been researching solar heaters as well. but in northern illinois the night-time can get cold!!!

like i said, i'm investigating EVERYTHING. we build spring of 2012. this is a SMALL cottage. less than 250 square feet. but we want everything sized for year round living.

everyone on this forum is so helpful! (thanks for not saying i'm stupid...i know u must be thinking it LOL)

BB. · August 2011

Re: cooking off grid

For a Fixed Array with 6x325 watt panels in Rockford Il:

"Station Identification"
"City:","Rockford"
"State:","Illinois"
"Lat (deg N):", 42.20
"Long (deg W):", 89.10
"Elev (m): ", 221
"PV System Specifications"
"DC Rating:"," 2.0 kW"
"DC to AC Derate Factor:"," 0.520"
"AC Rating:"," 1.0 kW"
"Array Type: Fixed Tilt"
"Array Tilt:"," 42.2"
"Array Azimuth:","180.0"

"Energy Specifications"
"Cost of Electricity:"," 8.4 cents/kWh"

"Results"
"Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
1, 3.39, 111, 9.32
2, 4.24, 123, 10.33
3, 4.65, 147, 12.35
4, 4.99, 142, 11.93
5, 5.38, 154, 12.94
6, 5.65, 151, 12.68
7, 5.79, 157, 13.19
8, 5.32, 145, 12.18
9, 5.28, 145, 12.18
10, 4.45, 131, 11.00
11, 2.81, 81, 6.80
12, 2.27, 71, 5.96
"Year", 4.52, 1558, 130.87

You will get roughly 71 to 140+ kWH per month (all system losses, assuming running an AC inverter) or:

71,000 WH per month / 30 days per month = 2,366 WH per day December
140,000+ WH per month / ~30 days = 4,700+ WH per day March thru December

Now--You just have to add up all your expected loads.

300 watt A/C * 10 hours per day = 3,000 WH per day
~1,700 WH per day to run everything else (possible)

Note, you should never plan on running 100% of predicted power output... You will have streaks of bad weather, guests that run more than you expected, and you will want to add loads.

A 1,900 watt solar array system is pretty good sized and would keep an off grid home running really well 9+ months of the year using "minimal" electrical loads (fridge, lighting, well/pump, clothes washing, etc.).

Adding things like A/C, under floor electric radiant heat, electric cooking, etc., and really add up the power requirements.

Turns out, that 15 minutes on a microwave or induction cook top is probably much less of a problem (few watt*hours per day) than a desktop computer, A/C, etc. which may run on lower power but for many hours per day.

-Bill

icarus · August 2011

Re: cooking off grid

Not to hijack the thread, but composting toilets (I suppose this relates to cooking!) really require heat to work at all. If you need to add the heat from electricity they become quite problematic to use. I know from experience.

Tony

Photowhit · August 2011

Re: cooking off grid

I think your close. I live in a tiny 160 sqare ft with a sleeping loft. It has a sleeping loft and I have a 2kw array. I'm well insulated, 6" walls and 10" floors, built in the shade.

While I only have 1600 watts up and running currently, into my tiny battery bank(still a rather hot charge for 220 AmpHour battery bank 24 volt) I've had AC for 4-6 hours a night and some in the afternoon when the batteries are finishing. I think with the long summer days(more sun, which comes with the heat at least here in Missouri) you may well be able to run the split umit on theremostat!

As to winter and heating. I don't think it is more than a dream cold often comes with grey days. I think a gas heater and perhaps running curculating pumps off solar might work.

-Whit via kindle, waiting on my forklift battery...

sgtalexmom · August 2011

Re: cooking off grid

icarus wrote: »

Not to hijack the thread, but composting toilets (I suppose this relates to cooking!) really require heat to work at all. If you need to add the heat from electricity they become quite problematic to use. I know from experience.

Tony

the toilet is still a concern of ours. we'd like to go no-septic, with gray water only, but not certain. just don't know if the compost system is something we could adapt to. concern about odor, etc., is raising some eyebrows here 8)

feel free to hijack! i'm learning so much from everyone here!

the nix is in on propane usage, so we have to make this all work.

Photowhit · August 2011

Re: cooking off grid

I forgot to mention about the composting toilet, be aware that it will work against you. Hopefully it will compost which will create heat, some people have problems with this for some reason, I suspect it is worrying about the smell and running extra fans or too cold an enviroment.

I choose to locate my bath room and kitchen in a seperate building. I'll run the heater in the composting toilet some in the afternoon during the winter. The idea is to keep the things tha create heat out of the house.

The vent fan will creat problems in another way as it will draw in hot air, while exhasting your cooled air.

I have the advantage of having a public bath house a couple blocks away, that is little used in the winter. I'll let the toilet go dormant in the winter.

About that hair dryer... It really is a big draw at typically a poor time, ever consider a bob?

dang my thumbs are sore...

-Whit via kindle

sgtalexmom · August 2011

Re: cooking off grid

Photowhit wrote: »

About that hair dryer... It really is a big draw at typically a poor time, ever consider a bob?

dang my thumbs are sore...

-Whit via kindle

the hair dryer is on the "won't give it up" list. it's 400 watts on the low setting, would run for 2-3 mins .... guess this could only be used at high sun times?

we never dreamed how finite we'd have to be with our wants.

the water system is next, not sure about well/septic build for such a small place!

Photowhit · August 2011

Re: cooking off grid

sgtalexmom wrote: »

...not sure about well/...

There's another load I don't have, we have a private well, serving @500 souls. Well pump people are around here somewhere...

400 watts for a few minutes won't be too bad, I was thinking 12-1500 watts for 5-10 minutes.

...I got the call and back on laptop, waiting for the battery who's truck grew over nignt from 41' box to tractor w/ 48' trailer...

icarus · August 2011

Re: cooking off grid

They do make Butane powered hair dryers.

Icarus

BB. · August 2011

Re: cooking off grid

You might find a 12 volt (or even a 24 volt) DC hair drier (car, truck, boat use).

-Bill

sgtalexmom · August 2011

Re: cooking off grid

BB. wrote: »

You might find a 12 volt (or even a 24 volt) DC hair drier (car, truck, boat use).

-Bill

it's been on my search list...so far no luck

henry1 · August 2011

Re: cooking off grid

zozomike wrote: »

Ive got 2 Max Burton induction cooktops that cause me no trouble, they seem to draw considerably less than advertised, and generally need to be used at level 2 or things will quickly overheat. They are efficient because cooking is FAST. Im soon adding a solar oven, I'm all solar here. I have a 1970 watt system and 12 batts. Don't know your resources. I can bring a quart to full boil in about 3 min, ( level 5) using 1100 watts. Since the cooktop is cool I often use heat retention, like a towel over the lid when cooking longer term items.
Michael

Like you i went with a induction cooktop & mircowave oven & toaster for my main cooking appliances in my place ..The most wattage i use dureing the week at my place is the Rv style combo washer & dryer unit on the sat morning launsdry day ..

Most of the time i go into town to do laundry on sat morning to have some town time around people dureing my weekly vist to town for supplies i need for the following week

I do have a Gas BBQ grill for cooking the meat on if i want to grill up as it need plus given the fact that i use my work computer for most of my basic computer need's and have Apple ipad as my internet device for use with place's with Free Wifi to conect to the internet to check email's and track package's that i have order from amazon and other places

The three appliances inside the place do all the major cooking in the place i have in the four corners area of the southwest..

mike95490 · August 2011

Re: cooking off grid

re composting toilet - check this older thread out
http://forum.solar-electric.com/showthread.php?t=5999
lots of discussion there, fans, heaters, vented, drains....

sgtalexmom · August 2011

Re: cooking off grid

mike90045 wrote: »

re composting toilet - check this older thread out
http://forum.solar-electric.com/showthread.php?t=5999
lots of discussion there, fans, heaters, vented, drains....

thanks for that link...

i should say that when we decided to build our little cottage and I said "we're going green!" the main response I got was "i'm not pooping in a bucket". :roll:

in a home we built years ago we had the chlorine type septic -- supposedly you could drink the water from the other end of it, i never did LOL. but, power, etc. just makes me want to stay away from a system like that. we're not keen on the cost of a septic system for a 250 sq foot home either!

people seem to satisfy themselves with the compost toilets in one way or another. i'm still looking....i know ours could not have the urine going through a drain -- that's black water and would need a septic.

glad i've got time to figure this all out

icarus · August 2011

Re: cooking off grid

A well designed, well built, well ventilated outhouse is a great alternative. The problem with most outhouse is they are not well designed, well built, well ventilated,, nor maintained.

A much better option IMHO than most composting toilets. At -40 they get a bit fun, but besides that, I wouldn't trade mine back to a composter,,, been there, done that.

Tony

cooking off grid

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