washing machine off solar?

[bxd20]

I was looking around the house thinking of an area where I could get my feet wet with solar. Some appliance that uses a decent amount of electricity so there would be some economic benefit, not just a proof of concept.

The best I could come up with was the washing machine. It's 110V @ 8amps. The longest wash cycle on it is about 30 minutes. So I believe that means it requires 440 watt hours.

This would obviously require a battery for storage. I looked at Optima Yellow, rating says 140 minutes of reserve capacity @ 25 amp discharge to 10.5 volts. I believe this is about 300 watt hours for 140 minutes.

Here's where I get lost. Can I compare those watt hour calculations? Can I assume that if the battery can supply 300 WH for 140 minutes, it will be able to do 440 WH for about an hour?

Then I realize I will lose power at the inverter, so that 1 hour will look more like 40 minutes, which should be enough for one wash cycle.

Are my calculations and concepts correct? I'm new to this, please go easy. Then all I need to figure out is how big of a solar array I'd need to be able to charge that battery in 48 hours or less. At my house I could face the array west or SW. Cleveland OH is the location.

Brian

[Naptown]

I would start with some lighting Not a large motor load.
Realize that to get 8A of 120V means 80A+ of 12v load. then there are motor starting surge that needs to be accounted for in the inverter. Peukerts law of batteries comes into play with high amp draws.

[Sunking]

Well if your intention is to save money by taking your washing machine off-grid to save money is extremely flawed and will be a very costly lesson if you implement it. Off-grid battery system the electricity will cost you 10 to 20 times more then what the electric company charges you. That only holds true if you utilize all the energy the system can produce in a day. Used infrequently like a washing machine load every two or 3 days that goes up to paying 50 to 100 times more.

You washing machine uses 960 watts and with a .5 hour cycle uses 960 watts x .5 hours = 480 watt hours. Buying that from the POCO cost roughly a whooping 5 cents. To do that with solar battery and you are looking at around $1500 with around $400 of that in batteries you need to replace every few years. So let's say the battery last 5 years, and you run the washing machine 3 times a week. So running 3 times a week you use 1.5 Kwh and there are 260 weeks in 5 years so it would use 1.5 Kwh x 260 weeks = 390 Kwh. If you buy that from the POCO at 11-cents per Kwh will cost you $.11 Kwh x 390 Kwh = $42.90. The Kwh cost to take that off grid is $1500 / 390 Kwh = $3.85 / Kwh

So taking the machine off grid will cost you 3500% or 35 times more than leaving it connected to the grid. Is that what you mean by saving money?

[Wy_White_Wolf]

Off Grid Washing Machine

Have fun!

[Patafil]

Nice. Those should be available at the gym.

[Sunking]

Off Grid Washing Machine

You read my mind. I doubt these youngsters even get it. Bet they are searching on thir Iphone.

[noone]

Hi

A washing machine would be about the last thing I would power from solar as there are plenty of other alternatives.

I actually use something like this (there are many similar brands/types).

http://camping.about.com/od/campinggearreviews/gr/wonderwash.htm

Works well and no power and can take it anywhere.

If you must have a powered washing machine then there are lots of low power portble ones though they too only do fairly small loads....around 240 watts is the smallest I can find in a quick search on ebay...actually there is a 2.5K kilo machine that may be less than 240 watts.

You might be able to find a 12 volt washer too though maynot be worth bothering for that.

I would not want to be doing a wash for a large family in anything like these though.

[noone]

Here is a 200 watt machine that you could ceratinly use off solar and may
well be worth experimenting with or to give a taste of "solar
living".

http://www.amazon.com/Panda-Portable-Compact-Washing-Capacity/dp/B005GM942C

Again I hope YOU are doing the washing and not expecting someone else to do it.

[Patafil]

I have a super capacity GE washing machine. It was the cheapest one at the local Sears. Tested with a Kill A Watt for fun. During wash cycle, the device registered 405 watts and around 365 watts during the spin cycle, but it peaks at 1600 watts for a second or two when the spin cycle starts.

[bxd20]

Sunking et al-

Thanks for your suggestions. I wanted a project that was large enough to really showcase solar power - running our rear exterior entry light (motion activated) just isn't that exciting, and since it's on about 3 minutes a day @ 19W, it's a completely negligible savings. Yet I wanted something small enough and self contained so I would not have to re-wire the main panel which any interior lighting project would probably require in my older home.

How are you arriving at $400 for batteries? I showed that by my calculations I might be able to sneak by with only one deep cycle battery. Perhaps I was being optimistic despite my inverter loss calculation - perhaps I would need 2 batteries which would be $200, not $400.

I am NOT saying my calculations are correct and you are wrong. I came here to be educated. I am asking that you please explain why I need 4 deep cycle batteries with 140 minutes of reserve power @ 25 amp discharge rate, each, only to run a washer for 30 minutes. Seems overkill.

Also I'm not sure why the batteries need replacement "every few years". I admit to not having experience with deep cycle batteries. Cycled a few times a year, they only last 3-4 years? I am used to my car batteries lasting 7, 8, 9 years even (vehicles garaged). I realize those are not deep cycle batteries. Again, I'm trying to learn about the lifespan of deep cycles.

Not a youngster at 36 but I am a newb to solar.

Thank you everyone.

[Naptown]

As I mentioned above Peukerts law comes into play
With a 12V battery the discharge rate would be about 80Amps
The battery you mentioned is a 66AH battery when discharged at the 20 hour rate or at 3.3 amps per hour.
That high a load reduces the amp hour capacity to 25.6 AH x12V = or 300 WH.
At this point the battery is dead you have drained it 100% and the spin cycle hasn't occurred yet.
If you drain a battery this far the number of cycles (discharge and recharge = 1 cycle) is dramatically reduced.
I could not find a chart for that battery for discharge depth vs # of cycles but I would imagine it would be less than 100
For longest life of a battery you want to discharge it on a regular basis no more than 20%, 50% occasionally not on a regular basis.
So if you need 400 Watt hours multiply this by 5 and divide by battery voltage.
In your case 400x5/12= 166AH battery
Or 400x5/48= 41 AH
Now we have to figure in peukerts law into the equation because of the high amp demand.
that 66AH battery in series at that rate is an 41AH battery each cycle is just about 20% depth of discharge.
If you used 4 of those batteries in series it works out about right.

Keep in mind that these are hybrid batteries not true deep cycle. You will not get nearly as many cycles from them as you would a true deep cycle.

[bxd20]

Rich-

Thanks for that reply. It answered a LOT of my questions. I had been going under the assumption that an Optima Yellow would be better than a traditional deep cycle -- sounds like a DieHard Marine would do a better job and cost less.

Most of all, thanks for the calculations as I can now take those and apply to other potential projects.

I agree that 4 batteries will take a lot more panel to charge than I had been hoping for. Will have to re-think.

Brian

[Naptown]

Any battery that states CCA or x minutes of reserve is going to be a hybrid battery.
True deep cycle would be a golf cart battery on the low end and a true RE battery at the top end.
Since most people destroy their first set of batteries learning how to use and care for them the cheap battery is probably best. Save the big bucks for the second set.

[Sunking]

Optima Yellow would be better than a traditional deep cycle -- sounds like a DieHard Marine would do a better job and cost less.

Brian Optima is a great battery, but not especially well suited for a true Deep Cycle battery. If you are talking about say a mobile RE application like an RV or someone living out of a van or truck, Optima would be an excellent candidate. Optima claim to fame is their very low internal resistance which is just what you want for a very efficient charging and very high charge and discharge rates of C/2. To achieve that feat they had to make sacrifices and came up with the Jelly Roll AGM VRLA cell. To roll the plates requires them to be very thin, and use a lot of them. Consequently thin plates make for short cycle life.

Lastly Optima is really geared for the mobile market. For example tow truck companies, mobile mechanics, utility companies, high-end A/V enthusiast, and low rider electro-hydralic lifts require very large amounts of current and these application will use a Auxiliary battery and a very heavy alternator. Optima is what they use.

[confused]

I was looking around the house thinking of an area where I could get my feet wet with solar. Some appliance that uses a decent amount of electricity so there would be some economic benefit, not just a proof of concept.

The best I could come up with was the washing machine. It's 110V @ 8amps. The longest wash cycle on it is about 30 minutes. So I believe that means it requires 440 watt hours.

This would obviously require a battery for storage. I looked at Optima Yellow, rating says 140 minutes of reserve capacity @ 25 amp discharge to 10.5 volts. I believe this is about 300 watt hours for 140 minutes.

Here's where I get lost. Can I compare those watt hour calculations? Can I assume that if the battery can supply 300 WH for 140 minutes, it will be able to do 440 WH for about an hour?

Then I realize I will lose power at the inverter, so that 1 hour will look more like 40 minutes, which should be enough for one wash cycle.

Are my calculations and concepts correct? I'm new to this, please go easy. Then all I need to figure out is how big of a solar array I'd need to be able to charge that battery in 48 hours or less. At my house I could face the array west or SW. Cleveland OH is the location.

Brian

Hi Brian
I notice that you have already received a veritable mountain of technical advice concerning your wish to run a washing machine from a solar source, so I won't presume to add to that.
However, I do live off-grid and I do run a washing machine. My advice, for what it is worth is, don't go there.
Assuming that you have enough cash to throw at the panels, the batteries, controller etc you will certainly need a pure sine wave inverter, as I found to my cost. My original setup was with a modified sine wave inverter and it took me an age and a lot of trips back and forward to find a washing machine that was SO simple that it would actually work at all. I have been forced to keep getting it fixed, as I am unable to find a replacement that will function. The more complicated washing machines these days just will not work, unless whirring a bit and then dumping water all over the kitchen floor is what you were after. i.e. getting your feet wet!
I'd pick a project that wasn't: a) so power hungry b) wasn't fraught with problems.
How about running your computer using solar power? Could be useful if there is an outage.

Regards
Confused

ps I have now upgraded to a pure sine wave inverter, so no more excuses to the missus the next time the washer breaks down.