Solar Power question for home

Sean

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Just wondering if anyone has experience with solar power for the home. Mainly, dumping power from solar panel(s) into the home during the day to curb monthy utility costs during the summer when the AC is running constantly.

How much would a set-up like this cost? It seems like it would be very expensive but I don't know for sure. It just seems like a good idea to be able to run the air conditioner for "free". But again, I'm wondering how many $$ it would cost for enough solar panels to actually run the AC.
 

raggie33

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darrel is the man to ask. he has some very cool stuff.here is a link from his webpage solar
 

Draco_Americanus

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expect to pay atlest 4 bucks a watt whent it comes to pricing solar panels. if you area is kinda windy why not go with a wind generator, they have smaller ones on the level of a few killowatts and run about 2 bucks a watt. I have a small solar array on my home but here in michigan it's next to useless exept in the summer time.
 

James S

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If you don't have batteries but just grid tie the system to try to run your meter backwards during the day (yes, if you generate your own power the meter WILL run backwards /ubbthreads/images/graemlins/smile.gif ) then it's considerably cheaper than a system that it battery connected.

First thing I would do is to find out if the electric company will even allow you to do that. In some places it's mandatory that they pay you for any power you generate, in other places they will take you to court for trying. though you can hook it up without them noticing, with anything larger than a few panels they will notice /ubbthreads/images/graemlins/wink.gif

Any of the modern inverters will be able to pump power safely back down the grid if you make more than you need at any given moment, even though the electric company is paranoid about this a solar panel and an inverter is very different than a dumb generator. If you hook up the generator wrong you'll kill the lineman working in your neighborhood, but none of the modern inverters will cause that danger.

You're still probably looking at tens of thousands of dollars though. Probably several to many tens of thousands of dollars. Depending on the size of the AC unit you're trying to offset and the amount of sun you get.

If you haven't already become a regular reader of http://www.homepower.com/ then you'll want to do that first.
 

paulr

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I don't know about MO, but in some states you can get a sizeable rebate from the utility commission for installing solar generation, so that covers a lot of the solar cell costs.

Solar cells cost around $5 per peak watt. Normally that's a misleading figure, since average watts are much lower than peak watts (i.e. if you want to use 100 watts averaged over 24/7/365, you probably need enough cells to generate 1000 peak watts, to account for nighttime, clouds, lower sunlight in winter, etc). But for A/C, peak sunlight is just when you need the AC the most.

You should also be able to reduce AC power consumption by adding insulation, A/C'ing just the room you're in instead of the whole house, and using high efficiency a/c's, if you're not doing all those things already.
 

James S

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[ QUOTE ]
You should also be able to reduce AC power consumption by adding insulation,

[/ QUOTE ]

This might actually be a better idea. While your solar panel would continue to lower your bills for ever. If you don't have the cash to get the entire bill covered by solar, then you might get more bang for your lesser buck by improving the envelope of the house and the quality of the AC units. AC equipment has come a long way in the last 5 or 10 years. If your equipment is older, consider an upgrade. the very efficient equipment is expensive, but not more so than solar panels. also more insulation in the attic and even the walls can be done. Window films, lighter colored roofing materials, better attic ventilation all these things can help a lot if you add them all together. You might find that you can improve the efficiency of your system to reduce your costs in a similar manner with quite a bit less upfront cost. And any improvements you make in insulation will help with heating in the winter time too /ubbthreads/images/graemlins/smile.gif

Course, if it's the coolness factor of solar that is attractive, or you have the investment to go 100% then that will certainly be more fun /ubbthreads/images/graemlins/grin.gif
 

Brock

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Darell has a similar setup to what you're looking for.

I have a small setup, 300w and a 5kw of inverter's and 10kw of batteries. I think of my system mainly as a house UPS, but do use the extra power to offset my on peak electrical usage.

I would look in to better insulation and possibly a more efficient AC unit. If yours is 10 years you cut you AC bill by 1/3 or more just by getting a newer unit.

I would think your looking at about $20-30k for a basic system.

Check out

http://www.wind-sun.com/forum/

for more info.
 

turbodog

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I have been a subscriber to home power for a while. I'd have to look further, but you should likely be able to get a grid tied system for 10k give or take. Will offset a rather large portion of your bill.

To look at this as a money decision...
dig up old bills to find monthly usage
cross reference this against solar exposure for each month
do the math on these figures
check w/ power company about grid tied systems (there are sometimes extra fees)
see how much solar equipment you need to buy

I figure for about 10k, you should be able to get enough equipment to save 100 a month on power (rough guess). If that's true, then you just made a 12% AFTER TAX return on 10 grand. And you will continue to make it... year after year. Good investment.

Let's see if this holds up:
10,000 total
1000 misc wires/brackets/switches/permits
1900 inverter (1800 VA)
7100 panels

7100 worth of panels @ approx $4.50/watt equals approx 1577 watts.

1577 watts/hour x 9 hours/day x 30 days/month = 426,000 watt hours

426KW hours @ $.09/KW hour = $38.34 month saved.

Hmmm, this seems really sucky...

If these figures are right, that puts the return around 6% or so. That is after tax though. More panels will obviously help. I would try to find some used panels. From what I know they do not deteriorate to any appreciable degree.

I a no expert (obviously /ubbthreads/images/graemlins/smile.gif ), but let me ask you this. What happens to energy costs as time goes on? They go up.... so the benefit of solar goes UP with time.

Also, our power is $.091/KW hour. If yours is different, that will change the results. From what I hear, we have pretty cheap power (and plenty of it too).
 

turbodog

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Stolen from bergey.com

***
The average U.S. home uses ~8,000 kWh per year. The average cost of electricity in the U.S. is ~7.5 cents/kWh.
***
 

turbodog

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Hmmm, the more I look the more I find.

There are some statewide/national programs to help you. The local power company here will pay ME $.15/KW hour for any electricity I generate. Then I can buy it back at $.09/KW hour.

This changes everything.

I can also get paid to sell my "pollution credits" that now I am not using to businesses who need them.
 

turbodog

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But, all this said, your return on investment is MUCH higher on boosting the efficiency of your home.

Insulation
sealing cracks
windows
door leaks
hvac system quality
CF light bulbs

You might wanna check into a ground source heat pump as well.
 

raggie33

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man solar power is so cool i even like thermal solar panels that heat water since it is preety easy to make a crud version. it owuld be cool to have a big aray of electic ones way out in country.so ya could be self powered a course ya wood need wood heat. and very low wattage lighting.
 

Darell

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I swear... this is like the fifth time I've tried to post, and after "continuing" my post just vaporizes. Oy. I'm sure it is human error, but it sure has happened a LOT.

So the simple answer to your question is yes, I do have experience with powering my home with solar panels. I also power my car that way.

Its my BD... gotta run to dinner. More later, assuming that this one sticks!
 

B@rt

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birthday.gif
/ubbthreads/images/graemlins/party.gif /ubbthreads/images/graemlins/grin.gif Darell!
 

paulr

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Turbodog, your figures based on peak power 9 hours a day (i.e. average power 37.5% of peak power) are hopelessly optimistic. It will be closer to 10% if even that. If you have 1577 watts of peak power, that means you get 1577 watts during the absolute maximum instant in the brightest day of the summer when the panels are directly facing the sun. During the rest of the day you'll get less power. During the winter you'll never get anywhere near that power. On cloudy or rainy days, you'll get relatively little power. Solar cell costs have dropped enough in the past few years to make sense for some remote locations, but they don't begin to compete with grid power for home use.

Wind power is closer to practical--it's cheaper and it typically works 24/7, but it's noisy and it's only windy enough in some areas.

Solar water heating does make a lot of sense--the heat collectors use the solar energy more efficiently than solar cells do, and they cost a lot less for a given area.

Depending on your location and winter climate, you might also think about an ice pond as an alternative to A/C. Basically you have a pond full of water that freezes on top in the winter and has pipes entering deep below the surface. In the springtime, you cover the ice with insulation so it doesn't melt, and then use the pond as a source of chilled water to keep your house cool all summer.

http://www.motherearthnews.com/index.php?page=arc&id=6686
 

turbodog

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My stuff needs tweaking I am sure, but I cannot believe effiency is that low. I have read plenty of documentation about people's systems that are completely off grid and they have enough power with not a huge amount more equipment.

Not to pick a fight... but look at it this way. If you're right... you'd need to spend 10 grand to power a single 60w light bulb 24 hours a day. I mean come on! /ubbthreads/images/graemlins/smile.gif
 

Darell

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[ QUOTE ]
paulr said:
but they don't begin to compete with grid power for home use.


[/ QUOTE ]Nope... doesn't compete. Kicks it in the ***.

Seriously though - I have real numbers here to back up the talk. I took a loan out to install my PV array ~10k. My monthly payments on that loan are about equal the my energy bill savings that the panels have offered me. I am paying the same thing for my solar power as I was paying for my grid power before. The part where it gets really exciting is that in seven years when my loan is paid off, my electricity is FREE. And my solar will be providing enough energy credit to power my house AND my main vehicle.

Interestingly, if the average household consumption is ~8000 kWh/year, then I'm proud to say that I'm even under that - WITH an EV being fueled. This is is my gross consumption - regardless of where my power comes from. I consume about 600 kWh/month for my car and my house (roughly they each use half of that).

Another real-world statistic that I have for you to aid in the calculation:
I have a 2.5kW system. On perfect days, I generate 19kWh (whoo-hoo!) My average is about 350kWh/month over the entire year.

(note: My generation numbers and "energy credit numbers" are not equal because of TOU billing). Whenever I state "kWh" it means just that, regardless of my credits.
 
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