Photovoltaic Panels (I want some)

[Rob Will]

Where are some good sources to buy photovoltaic panels? With a few pointers, I can install them myself.

What is your opinion of solar panels that track the sun? Are they worth the extra cost and will they stand up to wind?

I have 3-phase electricity w/ open Delta config (one leg measures 230V to ground). With the correct equipment, can I connect photovoltaic panels to one or both of the "normal" phases without messing with the wild phase?

There is a small hill with southern exposure and no trees directly behind my house. I also have an electrical shed out back that is the main distribution point for for the house and several buildings. Is there an easy way to connect panels out there without running wires into the house?

I realize that the cost / benefit ratio of this can be a challenge. I just think it would be a good thing to do and want to learn more.

Thanks for any advice or suggestions you care to offer.

Rob

[Brian Elfert]

A solar system is a generally a LOT more than just the panels. There are batteries, charge controllers, and inverters among other items needed.

The panels generate DC power that must be converted to AC unless you have DC stuff you want to power. Systems can be 24, 36, or 48 volt depending on the panels and how they are connected.

I don't know if you can do a system without batteries. A system with no batteries certainly can't provide electricity at night or during low light conditions. A charge controller controls the voltage from the panels so the batteries get charged properly and don't get too much voltage.

An inverter is used to convert the DC power to AC power and they generally cost $2,000 and up for a decent sized one. I'm sure they make three phase models for even more money.

I would contact the folks at www.thesolar.biz for a solar system. They seem to have good prices and they gave me good advice on batteries for a system that is not solar.

On edit: The reason for 24 volts and up is basically to reduce wire size required. You can do 12 volt, but that is generally for RVs that have 12 volt electrical items. 12 volt amperages can get really high and require expensive wire.

[Mike Henderson]

As Brian pointed out, there's a lot more to a solar system than just panels. There's one big factor to check before you figure out the cost/benefit. Some power companies allow you to put your excess power into the grid through your power meter. What this does is run your meter backwards when you're supplying power to the grid.

The net effect is that you're selling power to the power company at the same price that they sell it to you. So if you can generate enough in the daytime, you can suck power off the grid at night and not pay anything until you exceed the amount you sold them.

This is not sustainable for the power company but right now, many power companies do it because it's too costly for them to install the equipment to meter the back and forth flow of power.

This allows you to use the grid as a "battery". You still need to have real batteries on site but you won't need as many. Also, it's tough to generate as much power - through solar - as most homes use, but you can reduce your power bill through solar.

Mike

[Rob Will]

Thanks guys,
There is little danger of running the meter backwards around here (I wish there was). What type of bateries are we talking about, lead-acid?

Rob

[Jeff Bratt]

I've never heard of a 3-phase solar installation, although it is technically possible. Maybe it's because residential areas generally don't have 3-phase power... Anyway, you need an inverter to convert the solar (DC) to AC and a disconnect to tie into the commercial grid. You can do a lot of the installation work yourself.

Contrary to other posts, on-site batteries are not required if you are hooked to the grid. A system that includes batteries costs much more, and is less efficient. With a grid tie installation, you can run your electric meter backwards and reduce your electric bill to zero, although generally the power companies will not pay you if you generate more than you use.

Tracking panels provide about 15% more power per day than a fixed installation, at additional cost and complexity. Most installations use fixed panels.

A recent estimate was around $9000 per installed kilowatt of solar capacity for a no-battery system. The 2'x4' panels can generate around 150-200 watts each. A rule of thumb is an average of 6-7 hours of "full capacity" power per day - if you live in the southern latitudes of the US.

Another site with more information is http://www.windsun.com/

[Mitchell Andrus]

The net effect is that you're selling power to the power company at the same price that they sell it to you. So if you can generate enough in the daytime, you can suck power off the grid at night and not pay anything until you exceed the amount you sold them.

This allows you to use the grid as a "battery". You still need to have real batteries on site but you won't need as many. Also, it's tough to generate as much power - through solar - as most homes use, but you can reduce your power bill through solar.

Mike

Mike I know you're using extreme shorthand while summing up the concept - as long as we all remember that this arangement will go away as soon as the power companies sell closer to zero power during the day and normal capacity at night and on rainy days. Once the model goes 'upside-down', rates will go up to feed the beast (utility shareholders) and will effectively wash out any consumer benefits. The more people with installed panels, the sooner the model collapses. If we all had panels, who would we sell power to? The utilities don't store it for evening use.

Also, the 'battery' analogy is a quickie hook for a concept... we all know that the power company has to generate 'fresh' power at night. The power you pumped into the 'battery' on a sunny day is used up the instant it's created.

[Mike Henderson]

Mike I know you're using extreme shorthand while summing up the concept - as long as we all remember that this arangement will go away as soon as the power companies sell closer to zero power during the day and normal capacity at night and on rainy days. Once the model goes 'upside-down', rates will go up to feed the beast (utility shareholders) and will effectively wash out any consumer benefits. The more people with installed panels, the sooner the model collapses. If we all had panels, who would we sell power to? The utilities don't store it for evening use.

Also, the 'battery' analogy is a quickie hook for a concept... we all know that the power company has to generate 'fresh' power at night. The power you pumped into the 'battery' on a sunny day is used up the instant it's created.

You're absolutely right, Mitchell. There's no way the power company can buy power at retail prices and stay in business. And my "battery" concept is just an economic concept - as you pointed out, there is no storage in the grid.

You also pointed out one of the problems of some renewable energy sources - the power company has to have the generation and distribution capacity to supply reliable power, even when the sun isn't shining and the wind isn't blowing. When you add the reliable generation and distribution costs to the renewable generation capacity, it makes the renewable energy very expensive.

But because of the cost of solar installations, there's not many of them yet and many power companies are doing as I mentioned - buying power at retail. But that won't last forever.

I was not trying to mislead people and appreciate you expanding on the shorthand I used.

Mike

[Mitchell Andrus]

I was not trying to mislead people and appreciate you expanding on the shorthand I used.Mike

There are still some who cling to the pie-in-the-sky concepts and just don't 'get it' yet. You should see some discussions on forums devoted to this stuff.... Yikes!!! You'd think converting junkyard Vegas to electrics and putting 100 55 gallon drums of warm water in everyone's basement are real-world solutions.

Short-term, we need to get our own, state-owned oil production to produce oil for the USA so we don't have to buy at world prices. Not too much to ask of the greatest nation of earth. Long-term, a "Manhattan Project" style approach to nuclear power generation and cut the BS. Sooner or later, homes on oil and/or heat will need to convert to electric... we can't handle it as-is.

[Chris Padilla]

I'm heating my pool using the sun...still need 'lectricity to run the pumps, however.

Change is always in the air....

[Jeff Bratt]

Around here, the power company has already broken out some costs in the electric bill. We have separate charges for "distribution" and "generation".

While you are correct that the power companies cannot in general "buy at retail", the actual price of generating power is not the same all the time. "Peak power" - during the day - is expensive, while "night power" is cheap. Especially in the sunbelt, peak time is in the afternoon, when solar power is most available. So the power companies are actually OK with getting power from your solar panels during the day and then providing you with power at night. Most retail customers don't (yet) have time sensitive pricing, but large facilities often do.

Some of the most expensive electricity is generated by natural gas "peaker" plants that are built to be turned on quickly during heat waves, and then only get used three or four times per year. And there are already power "equalizing" plants that pump water uphill at night and then will use that water to drive generating turbines if needed during the day. And newer commercial air condition systems will "make ice" - or chill some appropriate refrigeration liquid at night, then use that for cooling/air conditioning during the day.

While the cost of solar power is generation is not now economically competitive with established baseline generation facilities, if costs associated with emissions of sulfur compounds, carbon dioxide, etc. get factored in the economic equation gets much closer. And if the efficiency of solar cells continues to increase, it will become viable solution for large-scale power generation.

For a proposal about very large-scale solar power generation see - http://www.sciam.com/article.cfm?id=a-solar-grand-plan

[Joe Pelonio]

I don't think it would work here, we go as many as 35 days without seeing the sun. I have decorative a solar light in the patio that light up nicely in July and August.

[Rob Will]

OK, let's keep this small and simple. What if I want to install a solar powered security light system on the roof of my shop?

If I make no attempt to grid tie the panels, what would be required to operate about 300 watts of fluorescent security lighting?

Rob

[Mike Henderson]

OK, let's keep this small and simple. What if I want to install a solar powered security light system on the roof of my shop?

If I make no attempt to grid tie the panels, what would be required to operate about 300 watts of fluorescent security lighting?

Rob

Cost is a serious problem. Let's say you run those lights 8 hours per day, 365 days per year, and you pay $0.15/kwh. The total cost of those lights will be about $131 per year (if I did the math right).

There's almost no way you could recover your cost for a solar installation, especially since you'll have maintenance costs for the system.

Mike

[Rob Will]

There are still some who cling to the pie-in-the-sky concepts and just don't 'get it' yet. You should see some discussions on forums devoted to this stuff.... Yikes!!! You'd think converting junkyard Vegas to electrics and putting 100 55 gallon drums of warm water in everyone's basement are real-world solutions.

Short-term, we need to get our own, state-owned oil production to produce oil for the USA so we don't have to buy at world prices. Not too much to ask of the greatest nation of earth. Long-term, a "Manhattan Project" style approach to nuclear power generation and cut the BS. Sooner or later, homes on oil and/or heat will need to convert to electric... we can't handle it as-is.

Actually Mitchell I asked the question because we need to explore energy sources other than burning fossil fuels. I have a 10,000 gallon diesel fuel tank in my front yard that needs to be filled before next month. Believe me, when that bill comes in the mail it brings a $35,000 reminder as to just how much we are dependent on fossil fuels. With the amount of fuel that my business consumes, I have no illusion about finding any one easy solution. Fortunately, I can afford to buy a couple of solar panels. There is nothing wrong with having an open mind and trying to learn about new technologies that may eventually help us all.

Rob

[Jeff Bratt]

A grid-tie system is simpler - however - quick and very rough estimate:
One panel puts out 150-200 watts. So two panels would power the 300 watt security lights while the sun is shining. Now, those panels cost several hundred dollars each...

If you want 8 hours of light (at night) that's 2.4KW-hrs
Should be 2-3 panels, charge controller plus battery storage for 12Vx200 amp-hrs, times a reserve for cloudy days. That will add several hundred dollars. If part of the service time is during the day, the battery storage capacity could be lower.

If you want 24 hour light: 300 watts x 24 hours = 7.2KW-hrs
Looks like 7-9 panels, battery storage for 12Vx500 amp-hrs (for nighttime), reserve, etc. Total will be thousands of dollars.

As Mike pointed out, costs for a completely off-grid system are high. You'll have to contact a solar system dealer for actual estimates. Also for an estimate of solar radiance in your area.

However, for a grid-tie scenario, if you just bought - let's say - 2 panels at $800 each. They will work, almost maintenance free (cleaning if doesn't rain?) for 20-25 years. At Mike's $130/year ($0.15 per KW-hr for 300 watts x 8 hours per day), there is a payback, but the time is still quite long - 12 years. If the price of electricity goes up, that time could be shorter. Note: this does not include an inverter - and 2 panels is probably too small an installation to justify a grid tie. Still, the payoff times are usually in the 15-20 year range.

Is that 10,000 gallons of diesel for generating your own power? Then you would have to figure your own power costs for comparison.