tesa's Off Grid System

Started by tesa, January 30, 2009, 05:57:51 PM

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tesa

for those waiting on me to post what the bid was for the PV folks who were gonna
design my system, i'm waiting too, as i was stood up today

well!!

i haven't been stood up in YEARS

LOL

so, i thought, maby i could do it myself

wasnt' sure if i should start a new topic, or add to this one

i've got a complete list of all appliances and their watt usage

except for these tiny RV lights, i can't find anything on their watt usage, but they are so tiny

and i can't find any info in our owners manual about the water pump's usage either

but other than that, i've got all my info

and also usage per day, how many hours i'm using certain items

whats my next step?

i also went to that great site, parts on sale dot com

i like their prices!

but i'm so confussed about which kit is right for us

they have both RV kits, and small cabin kits, and we were thinking that we might as well get
a cabin kit vs their RV kits

thanks in advance for any help

tesa
"building a house requires thousands of decisions based on a million bits of information"-charlie wing

Pritch

Tesa, do you have the RV lights right now?  If so, you can plug them into a "Kill-a-Watt" meter and find out how much power they use. 


http://www.supermediastore.com/kilwateldet-bulk-package.html

-- Pritch
"The problem with quotes from the internet is that they're not always accurate." -- Abraham Lincoln


MountainDon

#2
1. the RV lights are likely 12 VDC?   ???  Incandescent or FL ?   If they are 12 VDC, the Kill-A-Watt won't work.



2. Can you look the pump manufacturer up online and get the pump details?  voltage and watts or amps are required.


Without those you can still run one of the solar equipment calculators and see what they come up with without the two above things.
http://countryplans.com/smf/index.php?topic=6059.msg80681#msg80681

Just because something has been done and has not failed, doesn't mean it is good design.

tesa

with husbands help, i was able to discover the tiny lights draw 18 watts each and we have a total of 21

i wonder if i could find CF or LED lights that would fit, i'll poke around the net, as i'm
sure that would save some watts

also, daniel was able to assertain that the waterpump draws 84 watts

right now, we don't use it, as we're hooked up to city water, but once on the land we will

my list is 99% complete, i'm about to dig out the singer, and find out how much that will draw
and then i'm done

man, those watts start to add up, but the nice thing, i think, is that the rv is basically dc already, with
just the "add on" type things we run being a/c

is that how i size my inverter? i should add up all the a/c pulls?

tesa

"building a house requires thousands of decisions based on a million bits of information"-charlie wing

tesa

ow, that system worksheet was very confussing  ???

i think i'm gonna take a break

i'll be back on sunday evening, as tomorrow, we'll work the property, and i promiss to bring the camera
and post some pic's

tesa

"building a house requires thousands of decisions based on a million bits of information"-charlie wing


MountainDon

#5
Well, try doing this...

Divide all the loads into two groups, the 12 VDC and the 120 VAC items.

You are going to do the calculations for a 24 hour period.

Take the 12 VDC group first.
For each item multiply the watts X the number of hours use.
The result is the watt/hours of power for that item.
Add up all the total watt/hours for the 12 VDC items.

Then take the 120 VAC group.
For each item multiply the watts X the number of hours use.
The result is the watt/hours of power for that item.
Add up all the total watt/hours for the 120 VAC items.

Am I right in thinking there are no 240 VAC loads? No electric cook stoves, clothes dryers, for example. That would be very bad news for a PV system.

Then report back here with the total watt/hours for the 12 VDC and the 120 VAC items.

We also need to know where the house is/would be located to gauge the probable available solar energy.




Just because something has been done and has not failed, doesn't mean it is good design.

tesa

thanks so much don, for helping, i really appreciate it!

i did divide the load into dc/ac

we have no 240, stove is propane, no clothes dryer

i don't have my notes handy, i can post the spec's later,

we're only home for a bit, takin' care of some business, then its back to the
property for a few hours

i did a wee search for finding these tiny RV lights using CF, so far, i'm not finding any
that match

but it was just a quick look see

this dang rv has so many lights, some are singles, which draw 18 watts each, but we have many
that are "doubles" meaning that two lights come on, which will be 36 watts

i've been keeping track of how many hours we use some of these lights, like the bathroom lights
and the big light over the kitchen sink both doubles

so far, its not much, considering, the time it takes to use the restroom, and wash dishes in the
evening

i'll continue to monitor this

trying to design the system based on the max load of every light in the place being on at one
time would be bad, someting like 380 watts if every light was on at the same time

what are the odds??

should i really be doing that

after watching my family for a few days, it seems like maby one or two are on at a time, maby
three, and the max was 4 at one time after dark

our biggest d/c draw seems to be the fridge, at 14 watts, and it runs on an 8-hour cycle, but
we're looking at getting a huge propane tank, and running that puppy off propane

i'm thinking that might be cheaper than the watts

but i could be wrong


dang it, husband is telling me he's gonna unplug the computer if i don't get off and get
goin'

LOL

teas

"building a house requires thousands of decisions based on a million bits of information"-charlie wing

MountainDon

#7
If your RV lights are similar to ours, they either;
(a) use a bayonet bulb similar to older auto tail and turn signal bulbs, OR
(b) use a short straight fluorescent tube, one or two to a fixture.

I have never found a satisfactory LED replacement for type [a], and I'm 100% positive there are no CFL's that fit that socket.
(b) type FL's are fine. Most are made by thinlite.

You can get standard edison base 12 and 24 VDC CFL's that fit the normal household lamp socket. They do cost $$ though.



For hours of use keep track of the daily hours, always round fractions up and add a little as we are now into the days getting longer.



What kind of fridge is that? The usual AC/Propane/DC RV fridge? If so propane is going to be more economical than electricity you make yourself. An exception would to that would be if it used an actual high efficiency motor/compressor like the Danfoss. Those are not common and are $$.



Just because something has been done and has not failed, doesn't mean it is good design.

tesa

ok, so i should try the "thinlight" brand of bulbs?
i was thinking they would be expensive, but so is solar power, so i'm wondering if the
trade off is worth it?

i'll poke around and see what i can find

we found a replacement bulb at an auto-zone, so i'm guessing it is an auto type buld

but some of them are different, they have two prongs

regarding loads

heres my d/c loading info

21 lights, (which i'm researching as stated above)

the exhaust fan for the oven is 2.5 amps, which using a conversion on the web, it looks like
30 watts

fridge, is a norcold typical rv thing, i think, as another friend with an RV has the exact same fridge

we have an LP gas detector hard wired to the RV wich draws 120 milli-amps

each bunk has a little individual fan which draws 10 watts each (2 bunks)(they are d/c)

the water pump is a shurflow at 84 watts

the furnace draws 91 watts plus propane usage, but we're considering running that off the generator,
as our winters aren't too bad, and it might be ok ( i'm wearing shorts today, hehe)

our a/c loads are

computer at 70 watts which gets high usage, maby 4 hours a day, maby a bit more

we have a task light which has 25 watt bulb, but i'm thinking i could find a CF light to replace that one

our TV/DVD takes 80 watts and its on a power strip

we have a fan in the bedroom on a/c at 6 watts

and another fan we run in the summer, a table top type fan at 30 watts

we have a few things that are really used only a few times a month, like our pillow top air mattress
needs a "boost" every few weeks, but it takes like 2 minutes to use that

daniel has a wind up alarm clock, so no watts there, but i sitll haven't looked at my sewing maching

also, since were out in the boonies, i'm sure we'll have to get satellite for net service, so i'm not
sure how many watts that will take

thats it!

compared to a house, a small load, so i'd like to think

no coffee pot, no toaster, i'm gonna give up the microwave, no blender

and just so you don't think i'm a complete idiot ;) the thing on the worksheet that really threw me for a loop, was
the battery info

i've got no idea where to start there

daniel had a friend at an office near him give him like 9 batteries he said we could use, but when
he looked them up on the net, they werent' deep cell, we called the manufacture, and he said we
could use them, but after a few charges, you'll notice they don't hold a charge like they used to,
and were really only good for emergency type power

but they retail for like 200 bucks each, and they are brand new, so we're sittin' on like 1K worth
of batteries we cant use

bummer

tesa

"building a house requires thousands of decisions based on a million bits of information"-charlie wing


MountainDon

#9
The thinlites look like this...



They use small, 8" and longer, for different model lights, long FL tubes. They don't fit anyhting else. We have a few of them in our RV, installed as replacements for the old bulb style bulb light units.

I'm going to digest the balance of that post in a while.   :)
Just because something has been done and has not failed, doesn't mean it is good design.

MountainDon

Quote from: tesa on February 01, 2009, 06:12:47 PM

no coffee pot, no toaster, i'm gonna give up the microwave, no blender

and just so you don't think i'm a complete idiot ;) the thing on the worksheet that really threw me for a loop, was the battery info

i've got no idea where to start there



I could not give up the microwave and we didn't.  ;D

When you get down to the batteries just leave the fields as they are. You're using this one???
http://www.wagonmaker.com/script_calculator.html  It's preset for L-16 batteries like Glenn uses, with 3 (cloudy, little sun) days of reserve and a depth of discharge (DoD) of 40% (25% would be ideal, better for the batteries) and typical other data.

If you want to see what golf cart batteries would do just change the "amp hour capacity" field to 210.

Be sure to set the system voltage to 12 VDC (first box in worksheet 1; default value is 24.)
Just because something has been done and has not failed, doesn't mean it is good design.

Mike 870

Another way you could go about calculating your usage is get the 12 month KWH average from your electric bill and then calculate the deltas once you are off grid.   Meaning add on stuff like well pump but subtract anything you will no longer use. 

If your bill doesn't have this info on it, you could probably call your utility company and get it.

tesa

well, the RV park where we are actually does keep track of usage, as they give us a 500KW credit
a month, so anything over that is charged, we haven't gotten a bill since september due mostly,
i'm sure to not running the a/c

we're actually going to make some big changes that wouldn't be reflected now, like once we
get out to the land, i'm gonna give up the microwave, and the toaster

i'm still tryin' to work out all the juicy details on watt usage, i sort of forgot about little things
like the fridge light that comes on every time you open the darn thing, and daniels alarm
clock, which i'm tryin' to get him to switch to a wind up, but doesn't want to deal with the
evil noise those things make

i'm gonna sit down this afternoon, and give the usage calculator another go

i also realized the hot water heater has an electric start and it took up having to crawl up under the darn
RV to find that information

then i had to find a conversion chart to help me convert milliamps to watts

this has been very interesting, i never knew what a milliamp even was

i have been sort of pokin' around the web lookin' at solar packages and batteries

i think that "parts on sale" place has really good prices"

tesa
"building a house requires thousands of decisions based on a million bits of information"-charlie wing

tesa

ok, well, after working with the sizing calculator for several days now,
i guess solar is out of the question

its not that we can't afford the panels, and such

it seems the batteries are out of our budget

based on the calculations i ran
it said we would need something like 600 amp hours

when i looked at batteries, it was gonna cost us in the neighborhood of
2000 dollars for batteries?? 220 amp hour battery at 800 bucks, so we'd
need three??

if this is right, i'm screwed

did i do something wrong to get such a big number

tesa
"building a house requires thousands of decisions based on a million bits of information"-charlie wing


MountainDon

Which calculator did you use?   

You are saying that the total DC amp hours total up to 600 amp hours for a 24 hour day? Seems high for not using things like toaster or microwave.   ???

If your calculations included a lot of hours use of those RV incandescent type lights that may be where too much power is going. Incandescent lamps are terribly inefficient. CFL's are way better.

What batteries were you pricing out?





Just because something has been done and has not failed, doesn't mean it is good design.

glenn kangiser

Our L16's  are 375 ah each so 4 x 6 = 24v@375 amp hours.  They cost $210 cheapest wholesale, but average around $300 to $360 each on the net with some unscrupulous ones asking $559 I think it was.

We could get by with 8 fresh ones by working them hard but currently have 8 new ones in two new strings and 12 old ones in 3 old strings  of 4 in series.

Yes - it is easy to dump $2000 in batteries for rather heavy use or longer term with little sun....generator still required.   Battery life as little as 3 years if not cared for too well or 5 years if cared for better but the charger/rejuvenator/desulfators I should have in about a week may take that to as high as 15 years.  Results look good on the testing Mike is doing.

I think 8 L16's would get you by if that is your real rate.  In the day you can run from the panels and keeping the batteries - using the stored power fr the night.

Looks like we are at about 625 ah per day @ 24 volts   I didn't do the math - just estimating from what we can make.

We run 2 refrigerators, 2 freezers (20 and 8 cf) 1 1/2 hp water pump for 1 hr 15 minutes per day, washer - drier (propane)  lots of cf lights -   shop - saws - welder etc often.  Normal stuff.
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.

MountainDon

Quote from: glenn kangiser on February 03, 2009, 09:51:23 PM
Looks like we are at about 625 ah per day @ 24 volts   I didn't do the math - just estimating from what we can make.

That's why I suspect tesa's figures may have a glitch. I didn't think she would come anywhere close to that since they have a propane fridge (right?) no microwave or toaster. 

tesa, if you ran those numbers powering the fridge off the DC or AC (not off propane) that is a No-No for off grid. RV fridges on AC or DC use a heating element to get the RV fridge cooling system to work. Big power hog.
Just because something has been done and has not failed, doesn't mean it is good design.

glenn kangiser

We use a Microwave, toaster when we want and coffeemaker, however our coffeemaker is the Mister Coffee that brews then shuts off with the coffee in a thermal insulated stainless steel pot.

We have a demand propane water heater Bosch HX125.
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.

glenn kangiser

The high amp short term things - microwave - coffeemaker - toaster (unless you decide to microwave the thanksgiving turkey) are not a great problem unless the system is pretty marginal.
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.

tesa

ok, good nights sleep, a hot cup of coffee and i'm ready for a new day!

it does seem like we factored in alot of lights, i tried to write down everytime
someone turned on alight, and for how long,

i would love to try and find CF lights for the RV, but its
something i really haven't started looking at

i should move that furthur up the "to do" list

no fridge, no microwave, no toaster

and last night, daniel unplugged the alarm clock to see
if we could stand the noise the wind up makes

i didn't even hear it this morning  hehe

i wasn't sure about the battery thing, so i just started poking around
the net looking at "golf cart batteries" i also went to
solar sites looking at them

daniel told me to look for 12v and i found 220 amp hour but it
was that $800 one

since this is all greek to me, i'm having to really educate myself
and i'm finding that i'm getting a bit frustrated with my own
lack of knowledge when it come to these thing

i was terribly frustrated after i saw the prices on those batteries

but i'm not gonna give up!!

i'm gonna keep on seeking out knowledge/advise till i get
it right

my mission for today:

research CF lights for the RV
try to find a local source for golf cart batteries

(hell, houston is huge, surlly we've got some golf cart places here)

i understand how the basic idea of the battery works, it's our storred power for the night time, no sun
hours

i guess, we would really have to watch our usage after dark,

daniel thinks i'm freakin' out because i keep forgetting we have an 8K watt generator

tesa
"building a house requires thousands of decisions based on a million bits of information"-charlie wing


MountainDon

#20
A couple of points/opinions...

I doubt that you are going to find CFL's that will plug in to the RV fixtures, unless the fixtures have regular household screw bases. If you do, let us know because many will be interested.

If you can get the electrical loads down to where golf cart batteries can be used, Sam's Club has the best prices on them. Here in NM at least. Our cabin will start out with 12 golf cart batteries, that's about $900.

Golf cart batteries are 6 or 8 volt. Use two 6 volt ones in series to make the 12. We use 4 of them in our RV; 2 strings in series/parallel for 12 VDC.

We use battery powered alarm clocks. No sound until the alarm goes off. They seem to run forever on 2 C cells.

You could use the generator to power the RV along with a decent set of batteries. That's what we've done for a couple years now. However, I am so looking forward to not having to burn the gas.
Just because something has been done and has not failed, doesn't mean it is good design.

tesa

superbrightleds.com

interesting site with some led's i think we can use

husband is electrical engineer, so he's gonna have to check that out later

i found a really interesting webist that is for folks who go to "burning man" and i
found tons of posts about people replacing their bulbs with leds

i'll tell daniel about the 2 6volt batteries vs the one 12 volt thing

i trust you about the FC thing, as i struck out all the way around on that, but i
think the LED thing might be promissing

a "watt" of hope, if you will

i'd consider running the alarm clock off reg. batteries, i'm not opposed to that at all

i too am concerned about using the generator too much, but taking things one step at
a time is good for moral!

i just can't thank you all enough for your help, i wish i could send some cyber cookies, or
a big chocolate cake to each of you for your time :)

i'd like to think my learning experience will benifit others who in future or even now,
are reading this topic and learning, as i am

tesa
"building a house requires thousands of decisions based on a million bits of information"-charlie wing

MountainDon

Try the LED's, but I'd try only get one or two at first to try out. LED's tend to be very directional; great in a flashlight, but I find them unsuitable for tasks like general illumination. On the other hand they are miserly with power. Pricey too, IMO.

Just because something has been done and has not failed, doesn't mean it is good design.

glenn kangiser

Tesa, You will find the CF's much more pleasant to read under after about 5 minutes than the LED's at least until they improve more, but they are getting better and put out quite a bit of light but more to specific areas with a hazy non focused light around the edges.  I use them for prospecting - the headlight, and the 3w Maglight 3 cell mini-flashlight is super.

You may find local battery manufacturers that make the L16's rather than Trojan which are more expensive - key is the 375ah or so rating - they also are 6 volt so 2 required for 12 volt - 4 for 24 volt.  Maybe still as cheap as $250 or so.

On your amp hours were you figuring a 12 volt system or 24 volt system - big difference in required amp hours.

12v x 100 amp hours =1200 watts     24v x 100 amp hours is 2400 watts

Your continued contribution of questions and researched answers shared is all we expect. :)
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.

tesa

i agree that we need to try one or two and see how they work

i do have places i'd like good lighting, but at 2am in the bathroom, i don't really need to
see like i'm pullin' out a splinter on my toe

i did run the numbers using 12 volts,

i sort of thought the lights werent too bad, when you consider a normal house and how many
40-60 watt bulbs they might employ, so i thought my 4 36 watters were ok

i think the biggie was the water pump, i guess my thinking was it would need to be on at
least 1/2 the day, i don't wanna turn on the generator if i just wanna wash my hands,
but maby i could get creative about that too

it draws 84 watts and for 12 hours, thats a biggie, so i'm willing to look outside the box

other than that, i really thought our load was good

tia bunk has a wee 12v fan we bought at a truck stop, and it only draws 10 watts, but in summer
she sleeps with it all night

and in summer i plan to run my stationary fan at 30 watts, but it really moves air

the computer, at 65 watts is on alot, but being homeschoolers, we use it alot too, and i
feel its part of tia's education, so thats a must too

other than that, i really feel the only thing we can give on is the lighting

a friend of daniels gave us some MK batteries, daniel called the company, and they said
they wouldn't work for our needs, but such a shame as we have 10 of the darn things,
and they are brand new

when i looked them up on the MK website, they say they are 12v, and it seems they
are deep cycle

i wonder why they wouldn't work ???

their product # is m12260

and the bloody things are rated at 26 amp hours

any chance you'd look them up for me and maby you can figure out why we can't use them

not that i don't trust the folks at the company, but i just don't see why we cant use them

if you can confirm i can't maby someone else can?

i'd hate to just throw them out, not that i would, i'd for sure try to find a use for them, as
i know they can't just go into the landfill, maby if i could figure out who would use them,
i could offer them up on the trade/give away topic

tesa
"building a house requires thousands of decisions based on a million bits of information"-charlie wing