# A microwave oven question.



## unregistered358967 (Jul 17, 2013)

Bear with this newbie please who knows nothing. :help:

I currently live in a house that's on the grid and am looking at a home off the grid. 

Here are the specs of the off grid: 1260 watts solar power. 4000 watt true sign wave inverter with transfer switch. Outback flexmax 60 amp charge controller
Batteries- 4 Renewable energy batteries, Trojan L16-REB. 

She did not have a microwave and I didn't think to ask, but is one even possible? Though I don't use mine a ton, it is nice to have. I don't know how much wattage it is, but it's a built in, so I'd guess it has more than one of those small portable ones.

Those of you who have a living arrangement off grid, do you use a microwave? If you don't, how the heck do you heat up coffee..things like that? I know the stove heats things, like for making soup..no biggie, but I guess I'm thinking more of reheating things.

I should try to wean myself from the darn thing, eh?


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## wy_white_wolf (Oct 14, 2004)

With that system it's possible but, You don't want to have any other large loads going when you use the microwave and you want to limit it's usage to as little as needed. 

You also need to do a full inventory of what you want to run on the system (wattages and hours per day) to determine if that system will handle your needs.

WWW


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## TnAndy (Sep 15, 2005)

A countertop or over the stove built in will use 800 to 1200watts while in microwave mode. ( Varies by model, look yours up at the .gov Energy Star website ) 

So, yes, your inverter will handle that DEPENDING on what else you have running. Be aware that many newer MW ovens also have heating elements for browning, and convection cooking....those modes will use a LOT more power.

You also need to be aware of "phantom" loads....small uses here, there and everywhere that add up to quite a drain on a system if you're not careful. In the case of the microwave, that would be the touch pad and clock. New standards just formulated May 31, 2013 by the Gov require ones built from here forward to use far less energy in standby mode. You may want to put your MW on a switched receptacle so it is OFF when the switch is off, and drawing no load at all.

If you switch to off grid living, you have to be aware of where every watt goes....especially given the system you list is fairly small. I'd double that battery bank for starters...and then consider some more panels......at least get up to the 1600 watts the Flexmax 60 will handle if your system is 24v. If your system is 12v, you're already over max at 1260w of panels.....max recommended is 1200 for 12v.

You would need to add another Flexmax before you expand too much....go with the 80amp version next ( I have 2-60's and one 80 on my system )


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## Jim-mi (May 15, 2002)

Yes that small system will handle limited usage of the microwave. . .during the sunny day.
Using the micro for 10 minutes to heat up 'dinner,' after the sun is off the PV panels, will gobble up precious energy from the batteries.

At the very least that system needs a Trimetric in it so you can monitor where your batteries state of charge is.
Without the Trimetric you will soon kill the batteries from gross under charging .....


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## unregistered358967 (Jul 17, 2013)

Thank you everyone. I'll have to google those terms. They showed me the batteries but I honestly didn't know what they were taking about. I need to research more.

The current owner didn't have a microwave, but they had very minimal things, living a very simple life, so I wasn't sure if it was a lifestyle choice or that their system couldn't handle it...probably a choice, it seems to be.

I wouldn't dream of even getting a big microwave (it would stay here with the house)...just a small one that would stay unplugged unless we needed it to reheat something quickly or boil water. Speaking of boiling water, what do you all do for coffee? I assume we're not the only coffee drinkers... As of now we have a regular drip maker but I was eyeing a Chem-ex. Still, you need to initially boil the water. I suppose I'd use a teakettle either on the propane stove in the summer or on the woodstove in the winter.

So much to learn.... I've been weaning my family off the grid though.


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## PorkChopsMmm (Aug 16, 2010)

Just to confirm what everyone else is saying, yes you can run one. We live offgrid with a 2.8KW system and a 225 AH battery bank at 48V. We run ours during the day as needed and sparingly at night.


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## Harry Chickpea (Dec 19, 2008)

Be aware that they don't work as well or efficiently on inverter power. Switching from pure sine grid power de-rates them.


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## TnAndy (Sep 15, 2005)

Harry, 

She said she had a true sine wave inverter.

Many of the sine wave inverters for Alt E use produce cleaner power than utility grade. I'm not referring to the $300-500 models....but those up in the $1500-2000 range.


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## Jim-mi (May 15, 2002)

Harry, You would be correct --- if the inverter is a mod sine wave......

My sine wave inverters produce a cleaner wave form than what the utility Co. delivers to my pole....
I can put it on a scope and show you.........

The exception could be if she / they have the bottom of the line truck-stop cheapy inverter..............it doesn't sound like that is the case here........
The efficiency difference is minor.


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## idahodave (Jan 20, 2005)

I'd use it only when the sun is shining between 10AM and 2PM, otherwise it sucks a lot of power out of your batteries.

As far as coffee I use a Mr Coffee with a flip top lid, heat water on the stove and pour through the grounds in the coffee maker. Then use the maker as a warmer. The heater is about 800 watts, so it would take a fair amount of power to boil the water in the maker, but when used as a warmer the heater cycles on for a short period of time just to keep the coffee warm.


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## unregistered358967 (Jul 17, 2013)

Thanks everyone.

(and yes, I noticed my misspelling of 'sign wave'. I had copied and pasted that part).

Idahodave - thank you.


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## unregistered358967 (Jul 17, 2013)

http://www.pacificpower.net/res/sem/eeti/euc.html

Does this look like a good estimating system?


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