Storage needs Previewing Calculation

[drivingsouth]

Hi

On a 220V grid, i would like to have a capability to storage a 200K W/month medium, for my future windy generator. My home as all the stuf a regular house have, such as microwave, fridge, wash machine, 2 tv's, lights,...

How can i make some calculation to figure it out what are my storage needs, for some period of time of backup?

Thanks

[picmacmillan]

i would recommend you take how much you use right now and double it for monthly use....you can also make sure to have enough batteries to have a weeks worth of storage expecting the worst and no winds for that period..you could also go by what the standard wind in your area dictates...i believe where i am right now for instance it is common to have wind for three days and then no wind for three days...so if i have  6 days worth of storage, i should be good, but if you can afford it, get alot of storage...just my thoughts, may not be the same as others...take care...pickster

[veewee77]

I have an online calculator that I am working on that will do that for you.

It is not really ready for prime-time yet, but you can try it out if you want to. . .

You just go to the website, and follow the instructions for the loading and fill in the appropriate information and let it do the work.  each item is pretty well explained.

You can enter system voltage of 12, 24 or 48, how many amps the panels are and how many it takes to make the system voltage.  Enter the voltage and amp-hours of your selected battery and how many it takes to make the system voltage.  Enter the maximum number of no-sun days you would like to be able to go and it will crank out your total Watt Hours on a per-day basis, how many batteries it will take to run those Watt Hours (without ever draining the batteries below 80% (that is 80% remaining not 80% used)) and it will show you that conservation is the *first thing you need to do before you even think about going to a complete RE system.

[JeroenH]

it will show you that conservation is the *first thing you need to do

Quite correct. I've lowered my electricity usage to 1200kWh/yr, and that's for a 2-person household. CF-lights everywhere, energy-saving fridge, energy-saving washing machine (no hotfill yet), all devices with a standby function behind a hard switch. We have replaced our two CRT computer monitors with TFT monitors, and will be replacing our TV with TFT also (100W vs. 50W).

And of course common sense stuff like turning off lights when you're not in a room, filling the washing machine to the maximum capacity etc. Hardly glamorous stuff and a lot less sexy than PV-panels on your roof but it makes a big difference.

Living in a rental house there's not much I can do about my natural gas and water usages, but I have installed a water-saving showerhead (should save gas, too) and when I'm cold I put on a sweater instead of turning up the heating.

When we 'upgrade' to our own house I want to install a rainwater system for the toilet and the washing machine, that should save lots of water. When I can get the money together I also want a PV installation and a a solar hot water system. But that's for the future.

[drivingsouth]

And your site is??

Thanks

[veewee77]

OOPS!

Also, guys keep this to yourself since it is not quite ready for prime time, yet and still needs some work and tuning. . .

Study

Doug

[nothing to lose]

"When we 'upgrade' to our own house I want to install a rainwater system for the toilet and the washing machine, that should save lots of water."

First I think I would filter the rain water nicely and drink that, use junk water for toilets!

For saving water (and electric) something we have done and will do again.

We dump the soapy wash water as normal, we change the hose over to a 55gal barrel and save the rinse water. The rinse water is fairly clean, most of the dirt and soap etc.. goes out with the wash water. Fill the washer for the second load with the rinse water from the first load. After all this is where all the dirt and grease gunk is going to enter the water anyway, that rinse water is actaully pretty clean. Change the hose to dump the nasty wash water when that cycle compleates. Filling again with clean water for the rinse cycle and change the hose back to save that again!

 You use about half as much water as you normally would, and that adds up to ALOT of savings. You can use a low powered cheap pump from the barrel to the washer, that saves electric compared to running the deepwell pump. The only problem with the system is if you want hot water for the wash cycle, then you have to figure that out seperate. We don't use hot alot so that's not much of a problem here. Also unless you figure away to automatically change things you'll have to do that manually, we never found it to be that big of a deal though. I am setting it up basically automatic this year, I will be using well water for cooling the house, then let the water trickle through the solar heat tubes on the roof and into the hot water storage tanks durring the day. A hot water line will be driping into a barrel to use for the washer then.

 In this way I will pump cold well water, alot all at once into above ground pressure tanks well insulated. This keeps the pump from starting up all the time by storing lots of water at pressure. Then slowly dripping into a barrel or anything else that needs lots of water will keep the water flowing through the house for cooling and into the roof solar heating back into the storage tanks. Always keeping it moving and the hotest water in the tanks.

 You can also run the wash water through a filter to remove junk that could plug water lines and use the water to flush toilets. Just plumb in the toilet lines seperate to the tank and use a low power pump, keeping all wash water away from any other water lines.

Rinse and wash water will get stagnant and smell abit if you let it stand long enough in an open tank. Seldom a problem for us, use it often so it does not stand that long. Also probably dumping a little Clorox in the barrel would prevent that. For flushing toilets I will probably be running the wash water through the cheapest filters I can make and into a couple covered 55gal barrels.  About once a week or as needed toss in a table spoon of Clorox bleach.

Such simple things make a big difference. Think how much less that heavy 220v deepwell pump has to run if you reuse that 100gal of water the washer dumps! A small 12V pump uses far less power and will refill the washer and keep toilet tanks full just fine.

[nothing to lose]

You can go to Don Rowe and use their calculater to figure various ways.

 This is not working for me now with Firefox but I opened a (yuk) IE window and it worked fine.

http://donrowe.com/inverters/inverter_faq.html#how_long

They have a pretty good FAQ also if you read through a bunch of it. They have a little chart that shows about how much power various things use ect..

Basically enter 1 your battery banks voltage, 2 the amp hours of the battery bank, 3 the watts you plan to use. Hit calculate and box 4 shows your hours of runtime.

So play with it a bit and you can figure various things out.

 12V with 1000 amp hours battery bank at a 500 watt load gives how many hours?

Enter your Voltage 12 or 24, geuss at amp hours, enter your average hourly load, click calculate and get how many hours  you can run at that load on that many amps. If you don't like the answer enter higher amount for amp hours till you get the answer you like for the hours you can run.

To figure your average hourly load, Mine is 510KW per month average over 6 months time.

 So I divide 510,000 by 4.3weeks (actaully 4.3 weeks in a month) Almost 119Kw a week.

Divide 119Kw by 7 days = almost 17kw a day, divide that by 24hours and I get about 706watts per hour average. Of course you could probably just divide your average monthly usage by the hours in a month, but I like to know the other figures as well myself like weekly and daily.

So I go to donwrowes.com calculator and enter my 12v system, geuss amp hours (1000amps), enter my 706 watts I want to run and I find out how many hours I can run it on a battery bank of that size. That's 14.18 hours for me at 1000 amps. Go back and change to 2500 amps and I can run 35.46 hours. Divide the hours of course by 24 to find out how many days that would be. I find that at my present usage 1000 amps is less than one days backup, and 2500 amps is only 1.5 days backup.

I find by playing with the numbers a bit at my 705watts per hour I need 12,500 amp hours to last 7.38 days on battery power

Luckily at some point durring that 7.38 days I will have some power comming in most likely so I don't really need that many storage amps. But that's how you can easily figure out what you need for battery storage, decide how long you want to last on batteries only and figure your average useage out, then calculate various amps.

 My average may be less now, I changed all lights to CFL that run more than a couple minutes at a time. But then I also bought several power tools that will increase usage alot like my lathe/milling machine. So now I need a new average soon myself.