Posted by jeremy_ho on March 15, 2007, 10:40 pm
> > >>I am thinking of 7 15W panels rated at 1 amp max each, output for each
> > panel<<
> > 7 * 15W = 105W * 5 Hrs = 525 WH Daily production
> > >> If the computer usage at night average around 400W for 8 hours<<
> > 400W * 8 = 3200 WH
> > Of course, if you meant 400W total over the 8 hrs, I don't know of any
> computer
> > that runs on 50W. The power supplies in computers are 350W-500W. Of
> course,
> > you're not often at full load. But even with a conservative 150W figure
> > (including monitor), that's 1200W over 8 hrs. Still more than the 525
> produced.
> I had assumed that he was probably trying to run a laptop computer, and that
> he meant 400W of usage over the entire 8 hours. Or 50 watts an hour. That
> would be consistent with a 50W consumption and it would be consistent with
> the figures for battery usage that he posted.
> The fact that it's now evident that he is running a full size computer with
> a consumption of up to 400W an hour. At that consumption, you would kill a
> 100AH battery in a couple hours. You would barely get an hour of operation
> from a full day of sunshine.
> As far as full size computers that run on 50W...... I have a few full size
> computers that will run on less than 50W. They are not the new fangled
> things that you have now, but they are "computers". One of them, an old
> zenith, has a 20W power supply in it. An 8088 processor, 640K of ram, and
> two floppy drives. :-)
> On the more realistic side. A computer with a late generation P133, late
> generation mother board, with 64M of ram, and a single hard drive running
> win 95, would be running around 50W with an LCD display. It wouldn't be the
> top end of entertainment, but it would work for internet browsing. On the
> new product front, you can get micro motherboard running high efficiency
> processors that would easily run in that range. They are designed to be able
> to be run off 12V in a car or remote application. It would probably be
> easier to buy a low end lap top though.
Well, lesson learned! Since we are still talking about a off-grid
system. Can you tell me how do I handle the ground on the inverter?
Does it need to be tied the earth ground or is that a no no? I
searched and there is not alot of information, where does the
inverter's AC ground come from? The DC negative??
Do you guys know anything about "load switching" a device that
automatically jumps to use the grid power, hopefully it does not cost
too muhc.
Lets assume my interest is still to convert this 1 circuitin which 90%
of it is my computer room. (yes I realize I need more panels.. alot
more)
Posted by N9WOS on March 16, 2007, 12:15 am
> Well, lesson learned! Since we are still talking about a off-grid
> system. Can you tell me how do I handle the ground on the inverter?
> Does it need to be tied the earth ground or is that a no no? I
> searched and there is not alot of information, where does the
> inverter's AC ground come from? The DC negative??
For cheap portable inverters that you get at the supermarket. You want an AC
plug that has a pigtail ground that you can hook to a solid ground. The
ground pin of the plugs on the AC side isn't usual grounded to the DC
ground, or the inverter case. Don't ground the common on the outlet plugs.
Both output wires float above ground. You will do damage if you to try to
ground one of the two current carrying terminals.
For higher price inverters, designed for permanently installed house use you
will have a terminal on it's case that is designated for equipment
grounding. You will hook that to a ground rod.
> Do you guys know anything about "load switching" a device that
> automatically jumps to use the grid power, hopefully it does not cost
> too muhc.
There may be ready made equipment out there that would do that.
Other people will probably point you to some examples.
But one could be made with a heavy duty DPDT relay and a small bit of
circuitry that monitors battery voltage..
Normally though, for large installations, you would use a grid tie inverter
which would do that automatically.
> Lets assume my interest is still to convert this 1 circuitin which 90%
> of it is my computer room. (yes I realize I need more panels.. alot
> more)
What do you primarily do with your computer? Could you use a slightly less
powerful computer for most of your daily computer usage? A computer that
could be ran off of a 100 watts or so of PV panels. You can buy a pretty
good laptop for the price of the panels that it would take to run a computer
pulling 400W for 8 hours a day. Something like 800W of panels for a price of
over $000. I think I would be looking for a good laptop myself.
There is two sides to running stuff off of solar power. You don't just try
to get enough PV power to run what you already have. You have to work at
reducing the load that you have to run off of the PV panels. Because the
cost of the extra PV panels that it would take to run the existing equipment
will probably be more than the cost of a new unit that uses less power than
the old one.
And, maybe you should look for other things that you could run with a 100 to
150 watts of PV panels. If you have a moderate amount of CF lighting, or
other small appliances that you use on a regular schedule, you could power a
decent portion of the house. With 150W of PV panels, and 600Wh a day. You
would be talking about six 12W CF's run 8 hours a day. twelve 12W CF's ran 4
hours a day. Fifty CF's ran one hour a day.
Side benefit. If power goes out, you still got lights. :-)
Posted by jeremy_ho on March 16, 2007, 2:05 am
> What do you primarily do with your computer? Could you use a slightly less
> powerful computer for most of your daily computer usage? A computer that
> could be ran off of a 100 watts or so of PV panels. You can buy a pretty
> good laptop for the price of the panels that it would take to run a computer
> pulling 400W for 8 hours a day. Something like 800W of panels for a price of
> over $000. I think I would be looking for a good laptop myself.
Yes, I am assuming it takes 400W, maybe not, maybe like 70W and then
25W for the LCD screen, I have a kill-a-watt on order so that should
solve some of the mystery. Without it I have to estimate. I do
think I can move the computer use to a laptop, solar or not, probably
save a lot of power over 8 hours a day. After all we don't need 400W
of power to post to newsgroup and surf the web :)
> There is two sides to running stuff off of solar power. You don't just try
> to get enough PV power to run what you already have. You have to work at
> reducing the load that you have to run off of the PV panels. Because the
> cost of the extra PV panels that it would take to run the existing equipment
> will probably be more than the cost of a new unit that uses less power than
> the old one.
> And, maybe you should look for other things that you could run with a 100 to
> 150 watts of PV panels. If you have a moderate amount of CF lighting, or
> other small appliances that you use on a regular schedule, you could power a
> decent portion of the house. With 150W of PV panels, and 600Wh a day. You
> would be talking about six 12W CF's run 8 hours a day. twelve 12W CF's ran 4
> hours a day. Fifty CF's ran one hour a day.
> Side benefit. If power goes out, you still got lights. :-)
but I am saving 7 cents "worth" of electricity a day @ 600Wh.. it
takes 31 years to get even with the panel cost at $00. I can look
at it as a backup battery system to justify the cost.. but not have it
to gain edge over the PG&E bill.
I have made a new post at the bottom about this realization
Posted by N9WOS on March 16, 2007, 3:03 am
> but I am saving 7 cents "worth" of electricity a day @ 600Wh.. it
> takes 31 years to get even with the panel cost at $00. I can look
> at it as a backup battery system to justify the cost.. but not have it
> to gain edge over the PG&E bill.
> I have made a new post at the bottom about this realization
Yes, at current panel prices, there isn't much of an economic incentive to
use PV systems to offset grid usage. PV in that application is mainly more
of an environmentalist statement than anything else, right now.
But that doesn't mean that people can't have fun playing around with small
systems (getting their feet wet) until the price comes down.
The main area where PV stands out is where you don't have grid power, and it
would cost a lot of money to get it. A lot of times, the cost of running the
power line to the house is less than a PV system to run the house. In
situations like that, the PV system will pay for it's self on day one.
It will remain like that until panel prices drop to $ a watt, or $ a watt.
When you see $ a watt panels, then they there will be viable payback by
using them to offset grid usage.
When you can buy a 160W panel for $60 to $20 then you are getting into a
range where there would be payback in your application.
Posted by dold on March 14, 2007, 5:50 pm
jeremy_ho@my-deja.com wrote:
> I am not sure where to start, the rebates seems quite hard to
> understand, but I think a 3kW system is costing $0,000 after the
> rebates.
That might be about right for a grid-tie system, no batteries, installed.
Self-installed gets a lower rebate rate.
> I understand it might take 10 to 20 years to recover the cost, but it
At today's "e-1" rates, maybe, but the rates are going up, and you do want
the time-of-use meter to take advantage of net metering, where your energy
push during peak periods is worth more dollars than the energy you are
drawing from the grid at night. Based on old rates and no interest on the
loan, my solar system would pay off in 18 years.
http://cdold.home.mchsi.com/Solar-generation.htm $643 avoided in 2006.
Solar provided 59% of the energy I consumed, but because of the rate tiers
and TOU, that was 82% of dollars. That could make the payments on a 20
year loan for the system.
> BTW, Do I need to replace my meter to use the "time of use" plan?
> Does this cost alot to do?
The rules have changed, and continue to change. There is an interim
solution right now in PG&E territory that you may still be able to get.
E-7 is good, E-6 is the future, E-1 is probably not suited for solar.
http://dsireusa.org/
http://www.gosolarcalifornia.ca.gov/
http://pge.com/suppliers_purchasing/new_generator/ if you are served by
PG&E. There are some out-of-date links, and some links that are not
obviously for larger systems than you are likely to install.
http://www.energy.ca.gov/renewables/emerging_renewables/index.html
Account Activities
Completed Systems, 1998 to Present
This is an Excel sheet that you can sort by zip code or manufacturer, or
installer.
I am happy with my installer http://www.sunpowergeo.com/index.html
--
---
Clarence A Dold - Hidden Valley Lake, CA, USA GPS: 38.8,-122.5
XML site map
> > panel<<
> > 7 * 15W = 105W * 5 Hrs = 525 WH Daily production
> > >> If the computer usage at night average around 400W for 8 hours<<
> > 400W * 8 = 3200 WH
> > Of course, if you meant 400W total over the 8 hrs, I don't know of any
> computer
> > that runs on 50W. The power supplies in computers are 350W-500W. Of
> course,
> > you're not often at full load. But even with a conservative 150W figure
> > (including monitor), that's 1200W over 8 hrs. Still more than the 525
> produced.
> I had assumed that he was probably trying to run a laptop computer, and that
> he meant 400W of usage over the entire 8 hours. Or 50 watts an hour. That
> would be consistent with a 50W consumption and it would be consistent with
> the figures for battery usage that he posted.
> The fact that it's now evident that he is running a full size computer with
> a consumption of up to 400W an hour. At that consumption, you would kill a
> 100AH battery in a couple hours. You would barely get an hour of operation
> from a full day of sunshine.
> As far as full size computers that run on 50W...... I have a few full size
> computers that will run on less than 50W. They are not the new fangled
> things that you have now, but they are "computers". One of them, an old
> zenith, has a 20W power supply in it. An 8088 processor, 640K of ram, and
> two floppy drives. :-)
> On the more realistic side. A computer with a late generation P133, late
> generation mother board, with 64M of ram, and a single hard drive running
> win 95, would be running around 50W with an LCD display. It wouldn't be the
> top end of entertainment, but it would work for internet browsing. On the
> new product front, you can get micro motherboard running high efficiency
> processors that would easily run in that range. They are designed to be able
> to be run off 12V in a car or remote application. It would probably be
> easier to buy a low end lap top though.