Reply
 
Thread Tools Display Modes
 
Old 12-09-2009, 01:03 PM   #1
Mini-Skoolie
 
Join Date: Dec 2009
Location: hosuton, tx
Posts: 21
Year: 88
Engine: 7.3 international
solar system for running an A/C

ok i'm new. i've been researching all the ins and outs of building your own rv. this seems to be the place to get good answers. my background is mechanical engineering and design. but i could use some guidance with this electricity stuff.

my conversion will have interior space similar to a short bus (8'x8' floor) and 8' ceiling. it's not a bus. it has FRP sides, and i'll probly add a few layers of foam board insulation, with 5-6 inches on the roof. wile the air conditioned space inside is small the total vehicle length should be 30'. i should only use it for short trips, 2-7 days, 10-20 times a year, off grid. the rest of the time it will sit. on the short trips we will never have power hookups. i wanna run a small window a/c without pissing everyone else off by running a genny.

so 1000W A/C, in 100* 70-100% humidity weather. it'll runn a lot. i'm guessing 7 hours a day. it gets all the way down to 90-85 at night. some sites say i'll get 5 hours of peek sun per day. i know the sun is up and hot for 12 hrs+ all summer. not using the A/C is not an option. this project is about making trips to see the country more comfortable. if i wanted to "cut back" we would just drive in my car and camp. and we will probly still do that, just less often.

i'm thinking i'm gunna need 4 230 watt REC panels. that's 920watts of panels. i haven't found a single charge controller that will support that many panels. i will only accept a 3 stage charger.

so can you run multiple charge controllers to a single battery bank? can you run multiple isolated battery banks into the same inverter?
should i give up on the huge solar system idea and just cart 1500lbs of batteries around?
is there a generator that isn't gunna bother the tent campers in our group? it's gotta be VERY quiet and i haven't found one yet.
__________________
joining the u-haul club.
jam0o0 is offline   Reply With Quote
Old 12-09-2009, 06:13 PM   #2
Skoolie
 
bikeforthelight's Avatar
 
Join Date: Aug 2009
Location: Lakeland, Florida
Posts: 232
Year: 85
Coachwork: Blue Bird
Chassis: Ford
Engine: Gas
Rated Cap: 66
Re: solar system for running an A/C

Im looking at the honda eu generators. I used one a few weeks ago and it was quiet. I mean incredibly quiet. It was under the table we were sitting and playing cards at. Just hummed along. Honestly couldnt believe it. I was so surprised. It was the 3000w unit. Cost on it is around $1800. There is a similar unit from Kipor. Looks almost exactly the same except its yellow. It only costs $999. I have never used the kipors, but have heard good things. Either way, the honda or the kipor, I think it will be way cheaper than trying to build a solar setup to run the a/c all the time. Plus, like smitty said....you may have a really really hot rainy cloudy day, and you would be just fine.

*EDIT* Honestly, since you are running just a window unit in a small space, you could run the smaller honda or kipor units. You can get the 1000w honda versions for under $1000, the 2000w for around $1200. Kipors smaller ones are: 1000w for $400 and the 2000w for $550. All these prices are the norm if you just google them. I put some links to them at the bottom of this post. I know I saw the honda 2000w on sale at camping world a few weeks ago for $999. Also, check ebay or craigslist for them. Yamaha makes a really quiet genny too. Hope this helps.

http://www.go2marine.com/product.do?...F&WT.mc_id=gb1

http://www.islandwaterworld.com/brow...n/4,12010.html


http://www.americanrvcompany.com/Kip...RV_p_1523.html

http://www.americanrvcompany.com/Kip...RV_p_1519.html
__________________
Im Johnny. I Bike For The Light. I love missions. I think students rock. I make my mark.
http://www.bikeforthelight.com
bikeforthelight is offline   Reply With Quote
Old 12-11-2009, 12:54 PM   #3
Mini-Skoolie
 
Join Date: Dec 2009
Location: hosuton, tx
Posts: 21
Year: 88
Engine: 7.3 international
Re: solar system for running an A/C

i wanna get back to making a solar system big enough to run an a/c. 850 amp hours a day. plus some wiggle room for the fridge, lights, and tv. we wont run a microwave, heater or any other high demand devices. so it looks like 1000 amp hours should hold me. i know this isn't the budget minded idea that skoolie.net is full of. but it IS possible.

ok so lets think money no object theoretical huge cabin sized system. i know you can do this. i've just got to find parts big enough or than you can run in parallel.

the panels i've got all figured out. the batteries i've got all figured out, wire is easy. the inverter is purchased.
panels: 4 220 watt REC's
Batteries: 10 220 amp hour trojan T 105's
wire: 4 gauge from each panel to the controller(s). 2/0 for the controller(s) to the batts and the batts to the inverter. 4 gauge from inverter to breaker box. 12 gauge for house circuits.
Inverter: go power 3000Watt pure sine

pieces that aren't clear:
charge controllers: i haven't found one over 100amps. so i'm gunna need two that can have their outputs wired together. i've heard people complain about two crappy controllers being used in the same system that aren't rated for it. so what about the good ones?
__________________
joining the u-haul club.
jam0o0 is offline   Reply With Quote
Old 12-11-2009, 02:59 PM   #4
Bus Geek
 
lornaschinske's Avatar
 
Join Date: Jun 2004
Location: Roswell, NM
Posts: 3,587
Year: 1986
Coachwork: BlueBird
Chassis: 40 ft All American FE
Engine: 8.2LTA Fuel Pincher DD V8
Rated Cap: 89
Re: solar system for running an A/C

We have a 13K BTU Coleman TSR Rooftop AC unit on our RV. We have an Onan 2.5KW genset. This does handle the surge required to get the compressor motor running. In the RVing world, a 2.5KW genset is basically the minimum to run an AC unit. Our RV is 22 ft and we can freeze ourselves out with the AC unit (I run low fan and bump the thermostat up fairly warm). I have always been told that powering an AC unit with solar was impractical. Supposed to require too many PV panels and batteries. For that reason, we plan on using a couple solar powered deck vents like these: http://www.westmarine.com/webapp/wcs...classNum=12407

At most, we only use AC for a few hours per day (few windows in the RV) and mostly use the fan of the unit. I did run the AC unit while heading out west (temps inside were 90+, outside temps were 100+). I also ran the genset while heading down here to Corpus from NM. The genset powered the 120VAC 3cf fridge and 120VAC 4 cf freezer (all lights are 12DC and powered off the battery... which is charged by the genset or shoreline) along with a couple hours of 120VAC TV/DVD watching. We used about 1/4 gal gas per hours (or a little less).
__________________
This post is my opinion. It is not intended to influence anyone's judgment nor do I advocate anyone do what I propose.
Fulltime since 2006
The goal of life is living in agreement with nature. Zeno (335BC-264BC)
http://lorndavi.wordpress.com/blog/
http://i570.photobucket.com/albums/s...ps0340a6ff.jpg
lornaschinske is offline   Reply With Quote
Old 12-11-2009, 05:57 PM   #5
Mini-Skoolie
 
Join Date: Dec 2009
Location: hosuton, tx
Posts: 21
Year: 88
Engine: 7.3 international
Re: solar system for running an A/C

found it!

morningstar tristar ts-60
http://www.morningstarcorp.com/en/suppo ... .03.EN.pdf
page 8

ruff quote: any number of tristar controllers can be run in parallel in battery charge mode.
ok so i need two tristar 60's.
__________________
joining the u-haul club.
jam0o0 is offline   Reply With Quote
Old 12-11-2009, 08:01 PM   #6
Bus Crazy
 
Join Date: Jan 2008
Location: Upstate NY (Mohawk Valley)
Posts: 1,096
Re: solar system for running an A/C

Try using watt-hours per day instead of amp-hours. Remember, watts equal volts times amps. Figuring losses, it takes 11 amp-hours from a 12-volt battery bank to produce 1 amp-hour at 120 volts.

You say you need 1000 Ah per day. I suspect that's at 120 volts, so that's 120,000 watt-hours per day.

Four 220 watt panels give you 880 watts in standard insolation. We get the equivalent power of 4-5 hours of standard insolation up north in winter. You might get 6+ in the southwest. Since we are talking summer heat, let's make it 10 hours with never a cloudy day just for fun.

Solar panels max output: 8,800 watt-hours per day. A/C draw: 120,000 watt-hours per day.

If you really want solar air conditioning, you can develop my convection idea: Take apart a propane refrigerator, use the icebox coil in an air duct, and have a vertical solar collector on one side to activate the heat tube. Small computer fans run by PV would lift interior air through the coils to outlets near the ceiling.
__________________
Someone said "Making good decisions comes from experience, experience comes from bad decisions." I say there are three kinds of people: those who learn from their mistakes, those who learn from the mistakes of others, and those who never learn.
Redbear is offline   Reply With Quote
Old 12-13-2009, 06:58 PM   #7
Mini-Skoolie
 
mouse059's Avatar
 
Join Date: Sep 2009
Location: rochester, NY!
Posts: 25
Re: solar system for running an A/C

Quote:
Originally Posted by Redbear
If you really want solar air conditioning, you can develop my convection idea: Take apart a propane refrigerator, use the icebox coil in an air duct, and have a vertical solar collector on one side to activate the heat tube. Small computer fans run by PV would lift interior air through the coils to outlets near the ceiling.
That is a really good idea! One could use lenses to focus the sun on the plate where the propane would usually burn..This is a very workable idea, if you could get the pipes & hoses to where you needed them to be!
mouse059 is offline   Reply With Quote
Old 12-13-2009, 07:50 PM   #8
Mini-Skoolie
 
Join Date: Dec 2009
Location: hosuton, tx
Posts: 21
Year: 88
Engine: 7.3 international
Re: solar system for running an A/C

nope i converted everything to 12 volts already. 1000Ah at 12 volts for everything. it isn't really that hard to run the A/C. but it ISN"T cheap. i'm looking at
2500$ in panels
400 in charge controllers
1300 in batteries
500 inverter
200 battery monitor

so that's 5 grand. plus wire and other things i forgot
but it's silent.
and i have plenty of roof space for this. i just don't have a rooftop a/c, sky lights, or excessive venting.


edit: i'll look into how the propane fridges work and get back to you. if i went propane on heating and cooling it would save me a huge amount in electricy needs. i originally didn't plan on using any propane since i'm trying to limit the number of systems. but if i used it for a/c and water heating, and fridge... then it might be worth it.

double edit: i'd have to get one hell of a huge propain fridge. 5K btu might do it.
also i need to add 2 more panels to the roof. still plenty of space on a skoolie. but i m might have to rig up a folding awning over the cargo area of my truck to make it fit.
__________________
joining the u-haul club.
jam0o0 is offline   Reply With Quote
Old 12-14-2009, 08:19 PM   #9
Mini-Skoolie
 
Join Date: Dec 2009
Location: hosuton, tx
Posts: 21
Year: 88
Engine: 7.3 international
Re: solar system for running an A/C

i converted the energy usage (or is that power usage? i need to take physics again) from 120 volts to 12 volts. taking into account losses in the inverter. i got a 120 volt, 10K btu a/c that draws 9.2 amps (at 120 volts) according to the label. so that's 92*1.1=101.2. I rounded to 100 amps @ 12volts dc for my spreadsheet. it could be a lot lower but i havent gotten my kill-a-watt meter yet.
__________________
joining the u-haul club.
jam0o0 is offline   Reply With Quote
Old 12-14-2009, 09:46 PM   #10
Bus Nut
 
Join Date: Mar 2009
Location: California, Just NorthEast of San Fransisco
Posts: 539
Re: solar system for running an A/C

AC Hard Start Capacitor:

http://www.modmyrv.com/2009/05/27/rv...tart-capacitor
Sojakai is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Solar water heating system idea ThePimentals Conversion General Discussions 8 08-19-2014 08:12 PM
Solar ovens and solar water heaters/showers tomas_maly Heating, Cooling and Appliances 6 05-22-2013 12:43 PM
solar electic system wireing MikeyBskunk Electrical, Charging and Solar 3 02-26-2013 05:29 PM
House battery system charged by solar & alternator rhclayto Conversion General Discussions 12 03-18-2008 10:27 AM
Solar system question deadhead Conversion General Discussions 26 04-17-2007 10:05 PM

» Virginia Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 11:49 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.