Author Topic: Off Grid (Read 44119 times)

redoverfarm · « **on:** March 11, 2010, 02:43:00 PM »

OK People this is completely out of my realm of comfort. I need to get busy and develope a system to operate at my cabin. My main power and charging source will be a 12KW propane generator. I would like to operate the generator as a charging system for a battery bank and run the cabin when the batteries are depleted. Here is a list of what will I will be using. Some of which are not listed as watts but rather amps and some I am not sure what they draw.

1100 watts of lighting. That is a total but only a portion will be used at one time.

9.8 amp 110/120 well pump

1100 watt Microwave

2- exhaust fans. One is a bathroom exhaust and the other a 600CFM kitchen fan

1- Sure flow DC pump

3- ceiling fans

I know nothing about sizing the inverter or charging system or even the size or the amount of batteries.

Any information will be greatly appreciated. If you have any sites that list the equipment that you feel are a good buy that would also be useful.

Thanks

PS If I have a duplicate post I will try to eliminate it. Takes a while to figure the workings of the board. Please excuse.

Bruce S · « **Reply #1 on:** March 11, 2010, 03:56:47 PM »

redoverfarm;

Quite a list you got there.

First math: easy math when figuring out power use PIE that is the easiest one I have.

P=power or (watts) I=current E=Voltage.

Best to keep things on an even keel.

The well pump at 120VAC and 9.8Amps = E*I=1176 watts.

fans NO idea need units to figure.

DC pump:same since its DC probably 12Vdc send Amps or watts.

3 Ceiling fans do same probably 120Vac.

BUT WOW! your lights are pretty high 1100 watts!! this is AC lights?

Do you need a 1100 watt Microwave? 900 watter will run just as good heating most everything.

Generator sounds good.

FULL OUT GUESS but I'm thinking 6000 watts of AC power not counting losses you're looking at 50 AMPs if everything is turned on. IN DC terms (12VDC system that's 500 AMPS.

Better to go with higher DC system, 24V is a better starting point--me thinks--

Your gen, does it output AC? DC? or both?

This info could help to distribute the load.

Come back with somemore info and we'll go from there.

Sounds like a well set cabin. How big? how much time there?

Cheers

Bruce S

fabricator · « **Reply #2 on:** March 12, 2010, 04:31:17 AM »

It seems like you would be better of to just use the generator for power, if you use it to charge batteries then use an inverter to change to AC to run the cabin you are losing at every change along the way, do you plan on solar panels of a wind turbine in the future?

ghurd · « **Reply #3 on:** March 12, 2010, 05:44:30 AM »

That 1100W of lighting threw me too!

I roughly added up my entire 3-br house (including the basement), 520W.

About another 350W in the garage (including incandescents in the drill press, and band saw),

And about 200W of incandescents in the fridge, oven, dryer, microwave.

Another 100W of incandescents for the front and back porch.

Just barely broke 1100W for every bulb in the whole house.

Conservation is cheaper than fuel, RE power generation, and batteries.

Decent CFLs for the lighting.

A treadmill - type motor for the ceiling fans.

Smaller DC motors for the other fans?

Is this a 365 day a year cabin, or every other weekend place?

G-

tanner0441 · « **Reply #4 on:** March 12, 2010, 11:49:13 AM »

Hi

With your microwave is the 1100W the input power ie from the supply or the power from the magnetron, I have a 800W microwave in my camper but it takes nearly 1100W from the supply.

Also I have a 5 bedroomed house and our total lighting load is only just over 700W with CFLs it was over 2KW with incandecents.

Brian

redoverfarm · « **Reply #5 on:** March 12, 2010, 02:50:14 PM »

The lighting watts I listed are the bulbs used in the cabin(1050). I do have some flouresent bulbs in place but the majority are regular bulbs. The fans that I have which are 5 including an exhaust fan. The total wattage of the four ceiling fans are the high(speed) numbers with a total of 202 watts. The kitchen exhaust is 10 amp 600CFM so I would probably say around 1200 watts. I don't understand if I am just calculating this wrong or not in compariosn to others but my kitchen at the house has 7-65watts bulbs alone for a total of 455 watts.

Yes the Microwave could be downgraded to a 700 watt.

For the interested ones the cabin is 16X40 with a 16X18 bump out, 1/2 basement and two lofts16X14 & 16X18 and 1-1/2 baths, 20X16 basement. This cabin has taken me 4 years to build in May 2010 but I have done 98% myself. BTW to run grid power presently is $25K. Eventiually it will be more readily available as more land is sold and construction progresses by others.

This is a link to the cabins photos at different stages if anyone would care to look. I know that others forums enjoy "eye candy".

http://s220.photobucket.com/albums/dd161/redoverfarm/hightop/

Thanks for your repies.

John

redoverfarm · « **Reply #6 on:** March 13, 2010, 04:53:06 AM »

OK I probably screwed this posting thing up by duplication. It looks as if you have a good discussion board but I find it a little cumbersome in regards to posting in comparison to others that I am affilated with. Normally the post are in sequence with the later being at the top or bottom. But when I went to answer a specific post it places it midways in the thread. So I am not sure whether it will be displayed as a new or more recent reply or just get lost in the shuffle. Another thing is that there doesn't appear to be a correction tab, delete, edit or quote. I tried to look at the Menu but can't seem to find the actual explanations of some features. PARENT? Don't get me wrong it is just different. So anyway here is the posting again which was added to the comment of the last poster. If there was a way to delete the post originally I would but I am unable. Just like a small ball in the tall weeds.

The lighting watts I listed are the bulbs used in the cabin(1050). I do have some fluorescent bulbs in place but the majority are regular bulbs. The fans that I have which are 5 including an exhaust fan. The total wattage of the four ceiling fans are the high(speed) numbers with a total of 202 watts. The kitchen exhaust is 10 amp 600CFM so I would probably say around 1200 watts. I don't understand if I am just calculating this wrong or not in compariosn to others but my kitchen at the house has 7-65watts bulbs alone for a total of 455 watts.

Yes the Microwave could be downgraded to a 700 watt.

Oh yes I forgot one other inquiry was whether it will be full time. Right now it will just be occasional use probably a weekend thing or a couple weeks in the summer. That is unless my wife kicks me out for spending too much time there during construction and then it may become full time.

For the interested ones the cabin is 16X40 with a 16X18 bump out, 1/2 basement and two lofts16X14 & 16X18 and 1-1/2 baths, 20X16 basement. This cabin has taken me 4 years to build in May 2010 but I have done 98% myself. BTW to run grid power presently is $25K. Eventiually it will be more readily available as more land is sold and construction progresses by others.

This is a link to the cabins photos at different stages if anyone would care to look. I know that others forums enjoy "eye candy".

http://s220.photobucket.com/albums/dd161/redoverfarm/hightop/

Thanks for your repies.

John

TomW · « **Reply #7 on:** March 13, 2010, 05:09:46 AM »

John;

Yeah, Scoop [forum software] sucks bad!

That is why we are on a path to upgrading but it is stalled out awhile.

As far as display goes, that can be configured in preferences but as everyone can use different options [threaded,nested, time] how it shows depends on the user settings.

Each comment has a reply link. Using that should put it directly under the comment you respond to. For most folks anyway. By simply clicking "Post comment" on the story itself it will go in on the end of the comments list. Again, for most folks.

To add insult to injury, Scoop is known for ignoring [losing] posts for no apparent reason.

Anyway, it looks like we will be upgrading to Simple Machines Forum {SMF] software one day not too far off.

Then we should have the options you [and I] miss in a forum. No clue on the time line but it should happen "soon".

Hope that helps.

Tom

Volvo farmer · « **Reply #8 on:** March 13, 2010, 06:18:28 AM »

You need to do a load analysis. It does not matter if you have 100W of lighting or 2KW of lighting. If the 100W light bulb is on 24/7 it will use more electricity than 20 light bulbs that are on 5 minutes/day.

I will say this. If you are not planning on being there for long periods of time, and you only have a generator to recharge batteries, you are going to be very very hard on those batteries. An unattended set of batteries would benefit very much from a solar panel or three keeping them topped off during extended absences.

redoverfarm · « **Reply #9 on:** March 13, 2010, 07:22:44 AM »

Volvo I understand your reasoning but I really can't justify the expense of a solar aray at this time. At some time in the future this might be an option. I do intend to be very frugal with the power useage so that I am not constantly running the generator. ie: pumping the water to an in house storage (float valve) tank (300 gal) and supplementally a transfer pump similar to a surflow dc pump to charge the pressure tank and supply to the house. That way the pump will not run except maybe twice a week to fill the tank and should only be minimal. It is going to be very hard to determine the useage as I am not really sure how often that will be. I think I understand that the total watt useage is extremely high but that is if all were constantly being utilized at one time which will probably not ever happen under normal conditions. I realize that the advice given is for the best/worst conditions for permanently occuping the cabin which will probably never happen. If it does then I will cross that bridge when I come to it.

So where do I go from here. Can anyone suggest a forula or spread sheet to determine what I have laid out in regards to determining the inverter/battery needs.

Thanks again

Volvo farmer · « **Reply #10 on:** March 13, 2010, 05:05:25 PM »

Take every load you have in the house.. Every light bulb, every fan, every pump, microwave, television, cellphone charger, etc. Estimate how many hours/day you use it and multiply by the number of watts it uses. That is your load analysis. If you will never run a well pump off of batteries, and always run it off the generator, you can ignore that.

Once you have an estimate of how many watt/hours per day you will be using, people can suggest a size of battery bank and tell you how long between periods that you would need to run the generator.

Theoretically, you could run the whole house off of a couple 12V car batteries, but you'd have to run the generator every hour or so. Conversely, you could build up a nice 48V $5000 battery bank and maybe not have to run the generator for a week if you were very frugal.

If you refuse to do a load analysis, any help that people might try and give you will be a shot in the dark.

Lastly, the reason I recommend some solar panels is that batteries will self-discharge over time. You might be just fine leaving a set of batteries unattended for weeks or months at a time, but from what I have read about sulfation, I think it would be unwise to go from heavy charge/discharge cycles to unattended on a battery bank. Also I think it's going to cost you a fortune in propane to really get a good absorption charge in and I bet most people running a battery/generator setup are particularly hard on batteries because it costs like the dickens to have a 12KW generator idling away at 1KW to hold a battery bank at absorb voltage for two hours every time you do a charge cycle.

redoverfarm · « **Reply #11 on:** March 13, 2010, 07:26:43 PM »

Thanks Volvo. The pump that I plan on using is a soft start 9.8 amp pump unlike the larger pumps with a large surge . Without any other appliances running should it not work? I did find a work sheet for a PV panels which should be the same math applied. Maybe I will try it. I will post on the site when I get the replies.

redoverfarm · « **Reply #12 on:** March 14, 2010, 10:06:26 AM »

TomW I have looked for notifications via E-mail on related post but have been unsuccessful. Do they exist?

TomW · « **Reply #13 on:** March 14, 2010, 02:14:45 PM »

redoverfarm;

It never worked for me and I suspect it is disabled but not positive there.

Try the "recent activity" link on the right side top box. It shows unread posts. Its slow but works for tracking new posts.

Tom

wpowokal · « **Reply #14 on:** March 16, 2010, 04:36:52 AM »

This might help.....

http://www.kilowatts.com.au/downloads-kilowatts-pv-spreadsheet.php

allan

wpowokal · « **Reply #15 on:** March 16, 2010, 04:51:18 AM »

Don't you have a fridge to keep food from freezing

fridges are big load when starting, as already explained the microwave is also a killer.

I would use a 2Kw sine wave inverter, that requires 550-600 amp hour of batteries at 24V. Clearly as you already know stagger big loads. Battery capacity verses inverter Kw is important when starting those big loads so as not to dip the battery voltage below the inverter cut out point.

If all loads are switched off including the inverter and metering in your long term absence, the batteries should stay charged for months.

If not for that microwave you could get by with a smaller inverter.

allan

redoverfarm · « **Reply #16 on:** March 16, 2010, 04:56:42 AM »

wpowokal

Thanks for the reply. The refrigerator will be propane. Thanks for the spreadsheet site. The well pump according to the manufacturer can be operated on a 1200 watt inverter.

ghurd · « **Reply #17 on:** March 16, 2010, 05:34:02 AM »

I doubt a typical transformer-less 1200W inverter will start a 9.8A 120V pump.

The kitchen exhaust fan needs some serious re-engineering consideration.

That's more power than the pump, arguably more than the microwave, on a device that I imagine will run longer at a time, and only moves 600CFM.

DC fans,

http://www.fieldlines.com/story/2008/7/8/172317/7334

http://www.fieldlines.com/story/2007/3/10/23942/1876

I agree with VF, a solar panel or 3 would be money well spent.

Would not take many years to pay for themselves in money saved on batteries.

Fuel savings is almost a side benefit even if the panels were sort of undersized.

G-

Volvo farmer · « **Reply #18 on:** March 16, 2010, 09:15:15 AM »

Plus he needs to charge batteries with a generator. In my mind, that puts him in the camp that needs a 2+KW inverter/charger from Magnum/Outback/Xantrex.

ghurd · « **Reply #19 on:** March 16, 2010, 10:39:59 AM »

I was not so concerned with the charging as loads!

Dinner time? To me that means cooking.

Meaning microwave (1100W), water pump (1200W), light (100W), surges, and the only time a kitchen vent fan (1200W) would be used.

Plus any incidental loads.

That is straight into the serious category.

I did the heat and A/C equipped all-electric house boat vacation thing with similar conditions.

I made a rule to only cook/shower/ A/C when the gennie was running, and only run the gennie at those times. All other times was to be battery power, until the battery went to 12.2V which only happened once or twice (yup, old recycled Trace 12V system).

We used something like 1/6 or 1/20th or something amazing (I'd have to look it up) the gennie diesel as everyone else who were instructed to leave the gennie running 24/7, even though they ran the A/C much less than us.

The drone of the diesel gennie drove me bonkers. Saving a pile of money was almost coincidental.

G-

redoverfarm · « **Reply #20 on:** March 16, 2010, 11:45:24 AM »

I was mistaken by the needed wattage on the pump. But I had alredy submitted the post and for some reason I was unable to go back into the post to modify (Sorry I don't care for the format) . It was 1200 watts. As for the pump run time I would imagine it will only be enough to run @ 10gpm to refill a 300 gal storage tank (float valve). I intend to put something along the lines of a surflow DC pump to pressure it into the pressure tank and cabin.

"The Grundfos SQ pumps have SOFT-START electronic control built into the motor. Start up is slow and gentle over 2 seconds, requiring NO SURGE POWER. This pump runs off of much smaller generators(1700 watt or larger) or inverters(1200 watt or larger) of any wave form, and can have longer wire runs to the pump. SOFT-START also eliminates start-up twist and strain on plastic pipe installations. 24 month warranty."

As for the microwave it will only be intermittent with the warming of hot drinks or a sandwich or two. I will have a gas range and/or wood cookstove to prepare the meals. Like I stated before the microwave can probably be downgraded to a more user friendly one.

The range hood figures are actually on high. I would imagine that it will seldom be run with the exception of maybe "burning the beans" and this would be only for a limited time. There is no way to reduce the electrical consumption.

Thanks everyone. Eventually I think I will get this thing done.

redoverfarm · « **Reply #21 on:** March 16, 2010, 11:54:49 AM »

wpowokal BTW I cannot get the link to connect on the site you offered. I can pull up the company by itself by deleting the subtitales but cannot find the spreadsheet. Any ideas

ghurd · « **Reply #22 on:** March 16, 2010, 12:39:09 PM »

The 1200W is 1200W. Surge is surge.

Run at 10gpm rated to refill a 300G tank is not an exact rating.

Float Valve is almost irrelevant.

Imagine this?

Holding tank is almost down to min level,

lunch time,

wife kicks on the new 700W microwave,

vent fan is running,

couple ceiling fans,

then someone flushes the toilet.

Or the same situation at dinner, with a few lights, a TV, etc.

We are not trying to sell you something, let alone something bigger than you need,

we simply do not want you to buy an expensive something smaller than will work.

G-

redoverfarm · « **Reply #23 on:** March 16, 2010, 12:49:35 PM »

OK I guess I have this spreadsheet thoroughly confused. I found a "PV System Calculator V2.1.1.xls Microsoft Spreadsheet". There is several aspects that I do not thoroughly understand but this is what I got from it as the PV does not come into play. I am not sure whether it is required to make it total out or not.

27055.6 Correcrted Watt hrs per week of AC load

1127.317 Amp Hrs per week

10.42 Amp hrs per week DC load

1,137.73 Amp Hrs per week of AC/DC totals

162.53 Daily Amp Hrs Used

702.14 Amp Hr capacity per Batteries.

Does this make any sense to anyone.

Volvo farmer · « **Reply #24 on:** March 16, 2010, 02:03:49 PM »

That's about what I use, and we have an electric refrigerator, several laptops and the television is on 2-3 hours/day. Your actual real time use might be a significantly less if you switch to CFL and are ruthlessly efficient.

Here's what I would suggest: Eight T105s or equivalent, wired for 48V. You would have more storage with eight L16s, but they would also cost a lot more. You could learn about batteries on a cheap golf cart set and if you ruin them, you're not out thousands of dollars.

I would recommend at least a 3KW inverter charger by either Magnum, Outback, or Xantrex. I think you can get a Magnum MSW one for about $1500 but the pure sinewave ones are gonna run about two grand. Don't forget you have to program the inverter, with Outback that means buying or borrowing a Mate. I don't know about the other brands.

You're also going to need some sort of battery amp-hour meter. I use a trimetric, but there are several other brands available.. I think they run about $150. Put it where you can see it all the time. like next to the kitchen.

You might get by with a lot less, but since you've gone through all the trouble to build that beautiful cabin, why not just build a nice robust electrical system? Nothing is worse than getting up in the morning with no electricity, and having to get the flashlight, tools and meter and go poking around looking for the problem before morning coffee.

Good luck.

wpowokal · « **Reply #25 on:** March 16, 2010, 04:41:30 PM »

Here is one that is easier to use, go to this site then Information (in Menu box) then system design.

http://www.rpc.com.au/

allan

redoverfarm · « **Reply #26 on:** March 16, 2010, 05:16:17 PM »

Volvo

"Don't forget you have to program the inverter, with Outback that means buying or BORROWING A MATE. I don't know about the other brands." ?

redoverfarm · « **Reply #27 on:** March 16, 2010, 05:17:03 PM »

Thanks I will give that one a site and see what I come up with.

TomW · « **Reply #28 on:** March 16, 2010, 06:41:58 PM »

Outback inverters come factory set for reasonable default values. Not ideal for every situation or need so you can connect a "Mate" to it which allows you to monitor and configure the Outback line of equipment. Once it is configured you no longer need the Mate.

It allows you to place the Mate a couple hundred feet away from the inverter so you can monitor and control / configure it from another location. It uses standard Cat5 network cables. You can also monitor the Mate with a computer if you are so inclined.

I used mine for a year without a Mate but borrowed one to set it up to suit my needs. Lots of parameters can be configured.

Just to clarify what Allan mentioned.

Tom

stevend · « **Reply #29 on:** March 16, 2010, 06:58:46 PM »

I'm surprised anyone wouldn't buy a Mate to go with their system. How do you check errors/warnings? I guess if you can easily borrow one then that's okay. More surprising to me is that it's an optional item.

By the way, the Remote (equivalent to the Outback Mate) is an optional item for the Magnum inverters too.

Personally, having worked with both I find the Outback inverters are more resiliant to bad stuff happening (over temperatures, generator output being sent to inverter output due to poor system design) than Magnums.

-Steve

http://rimstar.org/renewnrg

redoverfarm · « **Reply #30 on:** March 16, 2010, 07:56:38 PM »

ghurd

Would it not be better to use a smaller pump (more energy concious) to energize the water system than the pump coming on everytime you flush the commode. Since this is for occassional use you can draw (fill the storage tank) up with all the water you would need for a weekend the day of arrival and it should last for the period of time you are going to spend without the pump coming on every so often to recharge the pressure tank and supply water when needed.

You have to understand that this is not a full time residence and some allowances have to be made in regards to knowing what you have to work with and using it accordingly. Living on grid is a luxury in comparison to the cabin but knowing that you have to adjust your lifestyle somewhat.

As far as the pump it is one of the lesser power hogs that I have found for a deep well. Do you have a better mouse trap let me know. Yes they do have DC pumps but they are at a premium cost wise. Almost 3 times the price.

I am open to suggestions.

Volvo farmer · « **Reply #31 on:** March 17, 2010, 03:55:23 AM »

To take things in a different direction... Generally, the smaller the well pump, the better in an off grid situation. However, think of it this way... You are going to be running a 12KW generator for what I would guess to be 10-20 hours for every week you spend there. I don't think you will be able to use more than about 1/3 that capacity to charge batteries, perhaps another 1/3 of the capacity to run the house loads... So if you are willing to load-shift the well pump to only the times you will use the generator, it doesn't really matter if it is super efficient or not, because you have 4KVA to spare, and the extra propane used will be marginal.

I think it's a great idea to store up water in a cistern like you propose. 300 gallons is a little small, but that might be enough water for several days if you're frugal. I would recommend gravity feeding the cistern to a place that you can put a standard 20-40 gallon pressure tank. We've used one of those little shurflo pumps with a 20 gallon pressure tank for over three years now and it works great. We can usually flush a toilet or wash hands without the pump coming on, I think we get something like 6-8 gallons between pump cycles and the little thing only uses 100W running. Since your pressure pump will be running off batteries most of the time, it is important that it is efficient.

If you were trying to live with solar/batteries rather than generator/batteries, I would have a different mindset regarding water pumping. I'm basing this off what you have told us about your setup so far.

Good luck

redoverfarm · « **Reply #32 on:** March 17, 2010, 04:37:22 AM »

Thanks Volvo

The storage tank will be in the basement at a predesignated location so gravity is not possible. Yes the well pump can be confirgured into the genset. The location was chosen so that I can annually drain the water system during the winter months when regular visits to the cabin are not possible due to the weather.

The biggest hurdle that I am finding is just how to wire the generator to make it function as it's intent as a standby with the house, batteries and inverter. I have listened to a generator for four years while I built the cabin and don't necessiarly want to hear it the complete time that I am using the cabin once it is finished.

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Author Topic: Off Grid (Read 44119 times)