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want to put together a small PV system
By dudevato, Section Homebrewed Electricity Posted on Sat Sep 18th, 2004 at 09:13:41 AM MST
to power computer/refrigerator..........

I'm thinking it would be fun to be able to power my brand new/large
side by side ref/freezer and computer with a PV system. At this
point all I'd like is an educated guess as to what a complete system would
run me, bought from a large scale supplier. I can do all
instalation/wiring/etc. I saw a sticker inside my ref. saying: full
load amp 6.5 My computer is used about 2 hours a day (brand new
Sony 250 gig hard drive/pent 4 processor) and the printer prints on
average a page every other day. I will scan a page a month. I have a
desk light (one of those loopy glass tube floresent types that get
maybe an hour a day use. This is for the fun of it and when the
power grid takes a hit it will be Very Fun.
With the above input can I get a ruff est. on what the components
would run me? I'm in southern california, 60 miles north of Los
Angeles. My roof is facing dead south and is in the sun from 7:30
am till 4:30 pm these days. I have one of those Kill a Watt
readers. Should I get a reading from it after a few weeks of having
it record my usage? But again at this time I would just like a ruff
est. on what you'd think I'd have to tie up in this 'hobby'. I'm
sure not much happens for $300, I'm hoping it won't take $1700!
Thankyou so much for your time and knowledge. dudevato

want to put together a small PV system | 8 comments (8 topical, 0 editorial)

Re: want to put together a small PV system (3.00 / 0) (#1)
by tecker on Sat Sep 18th, 2004 at 09:23:46 AM MST
(User Info)

search ther's a bunch of stuff here

dreaming (3.00 / 0) (#2)
by wdyasq on Sat Sep 18th, 2004 at 10:24:24 AM MST
(User Info)

Well Dudevato,

Appears you are getting about 8 Hours of sun a day. SO - you will need at least 3X average power consumption in panels to start taking care of the need. Makind more assumptions we will say the Frig stays on 1/2 the time and draws 500W running. A Pentium4 will draw near 100W, the monitor 45 Watts and 10 watts for the light. We won't think about the printer with very intermittent use. I get 6,310 watts a day and spread over 8 hours = ~400 watts of power. Since panels are rated at max Voltage of about 20V and get stored at 12V you will need 1.5X wattage

You will need a battery bank - $120(~per 2hr rough run time on the refrigerator) to $unlimited, an inverter for $everal hundred, , panel rack and possibly a tracker.

So far:

$2400 panels
$250 Battery
$300 inverter

OOPS - over budget!

Ron
Adventure is just bad planning." -- Roald Amundsen

Re: dreaming (3.00 / 0) (#3)
by jacquesm (j@ww.com- I run a whitelist, add 'stjoes' to msg) on Sat Sep 18th, 2004 at 10:48:06 AM MST
(User Info) http://www.greenbits.com/

an inverter that has enough oomph to start the compressor in a fridge is going to run a lot more than $300... running current is not the same as startup current.
www.greenbits.com
[ Parent ]

Re: dreaming (3.00 / 0) (#6)
by Ungrounded Lightning Rod on Sun Sep 19th, 2004 at 12:12:37 PM MST
(User Info)

Just because the sun is up doesn't mean it's bright. Most of the US only has 4-5 "solar hours" per day - IF the day is not overcast.

Then there's the issue of whether you're making full use of it by tracking the sun or just pointing the panels for best efficiency at noon. Solar trackers are expensive enough (and add a failure mode), and morning/evening sunlight weak enough, that you're about even money-wise to just get enough extra panels to make up the difference. Then you only adjust for season (which would be manual even with a tracker) rather than hour-by-hour - or set it for the season of maximum power consumption and leave it there.

[ Parent ]

more on solar hours. (3.00 / 0) (#8)
by Ungrounded Lightning Rod on Sun Sep 19th, 2004 at 12:26:56 PM MST
(User Info)

In particular, your location (if I got it right) has, in December, about 4.0-4.5 solar hours per day on a flat plate collector oriented due south and permanently tilted to your latitude, according to the maps at the National Renewable Energy Laboratory Geographical Information System.

Here's a link to Microtech's solar how-to. Plenty more to be found by googling for 'map "solar hours"'.

[ Parent ]

Re: want to put together a small PV system (3.00 / 0) (#4)
by dudevato (dudevato@yahoo.com) on Sat Sep 18th, 2004 at 12:59:45 PM MST
(User Info)

Thanks to all who posted. This project seems a bit expensive for me. Maybe I'll make a solar air heater. Now where did I put that extra patio door?

Re: want to put together a small PV system (3.00 / 0) (#5)
by kurt on Sat Sep 18th, 2004 at 02:46:46 PM MST
(User Info)

dudevato don't give up just lower your expectations to fit your budgit. how bout just running your puter off solar for now

my old jalopy of a puter pulls 130w including the monitor and dsl modem i measured it :) so if you use your computer 2 hours per day just one 12v deep cycle battery a 50w solar panel and a walmart special 400w inverter (or an old ups out of a dumpster) should do the job

if you shop around you should be able to get set up for $400 or so.....

http://www.reresource.org/

IRC
[ Parent ]

Re: want to put together a small PV system (3.00 / 0) (#7)
by richhagen (richhagen (a t) Juno.com) on Sun Sep 19th, 2004 at 12:12:50 PM MST
(User Info)

Since you are grid connected, might I suggest looking into a smaller grid tied system as there should be significant incentives in your area. The suntie inverters seem to be relatively cheap now, you should be able to get one and a few solar panels for your high end budget. You could expand your system when time permits. A smaller stand alone system would be possible for lighting or such for your budget also. I don't think your going to power your fridge and computer forever on that budget though. Refridgerators are one of the biggest power draws in the home.

The first thing I put up was small and simple, a 50 watt panel wired to a Trace C12 Charge Controller, wired to a 12 volt 'free' SLI battery, used to power the light in the coin laundry room of my three flat which is always on. The total cost of that system was about $350 and some labor to run the wires and such. After several years, and adding (and sometimes removing) more panels, small wind turbines, and additional loads, all of those original parts (amazingly even the battery barely although I moved it to another site that needed some light) are still productive and the light is still on in that laundry room. Make it a fun project, Rich Hagen

'A Joule saved is a Joule made'

want to put together a small PV system | 8 comments (8 topical, 0 editorial)

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