AUG 07

It sounds good, but there are several things about it I don't like;
-doesn't having segments that are spaced apart mean you are not utilizing all the available area? (also, proximity of separate units)
-because of the way of focusing the light, it means they can only work with direct sunlight (so wont work on cloudy days [with diffuse light]
-they look quite bulky, and (relatively) complex (so they may need higher maintenance, sue to complexity).

How are these mounted and secured to the rooftop?

If you mean, how are they mounted/secured on a residential/sloped rooftop, then they aren't.
They only work on a flat roof.
( http://www.energyinnovations.c...r_you.html )

But if you didn't mean that, then there is a supportive metal frame that they sit on, which can move to follow the sun (which is where I assume the problem of putting them on a non-flat surface comes in)

The cost to produce and operate a solar panel exceeds the amount electricity the panel generates during its lifetime.

Unless we can find a cheaper way to make solar panel, wind is a better choice for now.

1)Maintenance cost will be lowered if there are more companies out there that deals with installing these technologies. This will become a growing business in terms of the installation market.

2)it will work on slanted or flat roofs, that's what the mounts are for and the electronically tilting panels will still try to find the spot where the sun is shining so it can directly shine on the panels.

3)They focus the sunlight using a mirror much like a magnifying glass, so even when it's cloudy, the sun rays will still be brighter than what it is.

It can be very exciting to see this in mass production and on my company's roof top

"The cost to produce and operate a solar panel exceeds the amount of electricity the panel generates during its lifetime"

WRONG - Depending on technology, a solar panel will break even cost-wise in 18-24 months.

"The cost to produce and operate a windmill exceeds the amount of electricity the windmill generates during its lifetime"

WRONG - A windmill breaks even cost-wise in 6-9 months and that number goes down as technology improves.

http://cleantechnica.com/2008/...t-pay-off/

The article says that research shows that wind in urban settings is not the optimal place for them.

In urban situations, this kind of solar technology may be better than wind? Rural the roles could be reversed, or as the article states, wind power could be piped into the urban areas.

Wind is cheaper than modern solar technology excluding potential technologies like thin-film and concentrated solar.

I think it's safe to say, that is we hadn't though to concentrate the light with simple lenses then we haven't really given solar all that much thought.

With fossil fuels cost edge disappearing and a focus on pollution people are actually taking renewable energy seriously.

So...

Wind.. YES it's cheaper than current solar. However that doesn't mean if you try to install it at your home solar might not be more suitable for your geography.

The cost per kilowatt numbers are for solar and wind FARMS vs coal, nuclear, gas and others not your standard home application.

I believe what gives wind the edge is simply that the wind doesn't set every night. From a potential max output wind power wins.

Look at this mechanism to maintain. Think of snow and ice, if you live in the north, just about the time of year you really need power, and Poof!! great idea for so.Cal. and the like. Love the optics though. Gotta keep inovatin.

Dude that was soo cool. here we go again.

Jt
http://www.Ultimate-Anonymity.com

My concern is how much these things cost. Will the cost to install and maintain exceed the amount I would spend on electricity from the grid? That is the real rub.

I read about these kinds of comparisons at http://www.economicefficiency.blogspot.com the most recent being about polluting scooters.

My other wish is that this system could be included with a green roof, but hope springs eternal.

I have been researching adding solar to my house for a bit and so far can't find a way to it that ever pays for itself in electricity savings. I 1kw/hour system costs about $3500 after the state and federal rebates and produces about 4.5kw/day at my location (Montana). This is from a stationary system that I install. Perhaps the daily KW could be improved on, by panels that track the sun, but then it is assuming a cloudless day to get to the 4.5kw.

A system that generates 4.5kw/day will save me about $11.20/month but the $3500 initial investment would generate $14.58/month interest at 5%. So the bottom line is I lose my original investment of $3500 and $3.38/month more then the electricity savings the interest the $3500 would generate. It gets even worse by increasing the KW of the system because the state and federal tax breaks are one time and maxed at $2500.

A system that cost $2500, that I installed myself, would produce about 1.5KW/day on a cloudless day. That would save me $3.73/month. That is the only way to get solar to pay for itself. However that is assuming you could install it for free and your time is worth nothing.

When 225 watt solar panels sell for $100 each, so you can have a 30 panel system that produces 5KW/hour or 22.5KW/day, solar will be an option. Currently they sell for about $600-$1100 for used panels.

This concentrator is nice, but it is not the first, nor is it as compact nor as dense as the Soliant solar concentrator. Soliant had their first rooftop solar concentrator the better part of a decade ago:
http://soliant-energy.com/products.php

The Soliant model is also much nicer looking, IMHO.

Terry, you're looking at costs in a very shortsighted manner. Energy costs will continue to increase just based on inputs, additionally, inflation is eating the dollar faster than that 5% you can only get from a jumbo CD for 10 years currently. Combine that with the benefits of at least marginal self sufficiency and you can surely conclude this to be a winner, not a loser.

Actually I was basing my investigations, into solar use, based on a 10 year cycle. We are on a rural coop and currently pay $.083 per KW. It has doubled in the last 10 years and most likely will again. Even compared with double the cost of electricity a 1kw system is a poor investment and any larger system much worse as you only get one shot at the $2500 tax rebates.

Sadly a 1kw system would only meet about 1/11th of my summer usage and about 1/22nd of my winter so virtually no self sufficiency. To be self sufficient I would need a 15KW system at a minimum. That would cost about $90,000.

If solar is ever going to be an alternative the panels have to come down in price. If mass production dropped the cost of panels to under $100 for new panels with a 20 year life solar would be viable. Either that or the output of a panel would have to increase 1000 fold.

The company that makes the collectors this article talks about claims their collector would produce about 5 to 5.5KW/day for Montana. That is an increase over the current 4.5KW/day that traditional collectors give but no where near the 45-50KW/day that would make a 1KW system fisable for the costs involved.

Leave warm feelings out if it and run a few spreadsheets that analize the costs involved. Double or even triple the cost of electricty for a 10 year period and see how things look. I would love to find a way. We have a super efficient heat pump, a zoned programmable thermostat, and a well insulated house but still average $200 summer and $400 winter monthly electric bills. Perhaps in another 10 years things will be different. The best way to save money on electricity currently is through conservation.

Read the site, even the manufacturers of this say it will only work on flat roofs, and they will only work with direct sunlight (i.e. not when cloudy).

Hi.

As you seem like someone who takes solar quite serious and is prepared to invest/research it. Why not try a Solar hot water system while you wait for the price of PV to come down.

These systems tend to be cheaper and more efficent, making them more likely to cut your bills.

I made a design for a passive solar collector that heats air and cycles it through an 8’x8’x6’ earth integrated and insulated box that is filled with large rocks. A coil of copper tubing would allow water to be circulated threw the box at the top to move the heat from the rocks to a swimming pool in the summer and to a radiator embedded in the furnace cold air return in winter. The collecting panels on the top of the box would rotate to catch more sun then the typical 10-2 period. By inserting a metal sheet between the collectors and the box, with holes set to stop air flow during the hours when the sun wouldn’t provide heat, loss of heat through the collectors could be reduced and the collectors would only have to rotate on a 24 hour basis rather then travel in 2 directions. I haven’t built a test one yet but will as soon as I finish my current shop project. Heating the water directly would be simpler but rotating the panels wouldn’t work unless I engineered the collectors to work like windshield wipers. Also the rock would provide heat storage and allow for multiple runs of copper tubing through the box. I am thinking one for the pool in the summer that cycles the pool water through the box and one for the winter that cycles water with antifreeze threw the embedded radiator that would prevent the line freezing if everything went cloudy for a week or so. It’s not photovoltaic but a small dc motor could be used to rotate the panels and be powered by a small panel. The costs for such a system would depend on ones ability to build it. Some obvious ways to improve on this would be to have the box integrated in the house or lens on the collectors to magnify the sun but I am not willing to sacrifice room in the house and don’t want to dig up the basement floor to add the box.

If more people build strawbale and earthship houses the need for heating and cooling is decreased by a magnitude of 3-5 times.. Strawbale has a r value of appx. R-90 compared to the standard R-19 fiberglass insulation.. Earthships can have an ever higher R-value and are usually designed to have south facing windows for extra solar collection.. When people continue to build "standard" homes with such enourmous energy waste as part of the design it's no wonder it takes so much energy to heat and cool them.. With solar water heating the energy needs for strawbale/earthships are minimal.. Cheers

Hi Terry,

I don't mean to single you out in particlular. You sound to me like an engineering type of person who has accumulated a high energy lifestyle in the good old days of cheap fossils. I am also in a similar situation.

Now I am more climate change aware. I want to do something. I am desperately trying to figure out how to engineer my way to a better "high energy" future. Like yourself, I find the cost saving calculations never do quite pan out.

After dreaming all night. When I wake up every morning, I'm still driving my SUV and sucking up those coal fired amps. My inner common sense tells me my habits need to change. My native intransigence stops me from changing.

Next year I am moving house. I will have a clean sheet and can do the "full monty" on energy saving. For me, it's too difficult to change my family habits and figure out how to make my current set-up more efficient. I need a fresh start.

I guess you will eventually figure out the best way for yourself.

I suppose our electricity usage looks high to many but it is the only energy source commercially available except for propane, so our home is all electric. I tried doing a wood stove for heat but felt the pollution from burning wood, coupled with the frequent attention that stoves require, was too much. Same for coal though there are coal feeders. The problem is the pollution.

I feel the best approach for us is to reduce consumption and add solar heating and electric when practical. The points I made about the cost of solar electric are the single limiting factor to the acceptance of solar electricity. Unless they are addressed no amount of guilt over usage is going to push most people in that direction.

I don't feel picked on. The people that respond to this site seem very informed and concerned. They also are usually very polite. I also don't feel our life style is high energy. The house is kept at moderate temperatures, regulated by a zoned, programmable thermostat. Our heat pump is one year old and has some of the highest efficiency ratings for heat pumps. Our home is well insulated and only a bit larger then I like, (1750 sq. ft.), but zoned so the extra rooms are offline unless needed. Our car is a Toyota Camry and gets 34 mpg!

If I had my way I would move to someplace warm in the winter and return here in the summer. That would eliminate 50% of our energy usage but since my wife still works and will for another 15 years such annual relocation is not possible.

The solar heat collector I have designed should help with winter heat needs. The swimming pool I talked about is one of those kids pools that you put air in the ring and then fill with water. Currently I heat the water with a homemade solar heat collector and to layers of bubble pool covers. This is needed as the summer night temperatures here can get into the 50s. The water stays at 65-68 without heat. I can swim in 68 but the kid turns blue in a matter of minutes at that temperature. Other then a small filter motor the pool uses no electricity. I just thought if I was collecting the heat from a house size collector I would use a bit of it to heat the pool.

When the wife retires and electricity is 3 times what it is today the summer winter relocation might prove the most cost effective way to reduce electricity usage. A projected savings of $1000 a month on electricity, for 4 months of winter, would easily pay for the travel expenses. If I buy the property now and rent it for 15 years I would build equity and should have a paid for smaller home for winter usage in the future. That would be a much better investment then $60,000 for solar today.

I realize that the driving force for many is the desire to reduce carbon usage. My wife and I feel the same way. I just feel it has to be more reasonable to be acceptable. Being on a fixed income, I am retired, and my wife's income being eaten up by dollar depreciation, inflation and the high costs of raising a child, I don't think "paying extra" to go green is the best course for us. No guilt. Compared to most, in America, our power usage is not high.

Do the pv cells of this solar concentrator require cooling? If so, this would be an excellent system to provide additional savings on hot water as well. Solar/thermal systems have also been used old technology to provide cooling as well. Every commercial building in the sunbelt should have some such system integrated into it's roof. Have sliding scale tax credits for companies to experiment with. The greatest improvement in efficiency gets the biggest break. We need to get moving on this or be prepared to fight more wars over dwindling resources!

I don't see what all the fuss is about heating costs, if it's cold, just put a jumper on.

Our biggest energy load is heating/cooling/hot water. That's why I've researched geothermal heat p umps. They, too, are expensive. If you can finance the purchase for long enough, through home equity or whatever, you can be cash-flow positive from day one.... if you have access to that kind of money.

Yes, of course, when you're building a new house, you can do lots of cool stuff, but for older houses, retrofitting is a bit harder. (Our house was built in 1914).

Does it filter UV rays? otherwise it will burn up the panels

The real challenge with solar concentrator technology is removing the large amount of heat generated. Any kid who ever burned ants with a magnifying glass can tell you a thing or two about it. If it's not removed, the solar panel will quickly be damaged.

Personally I think the lens-type concentrators add too much cost to the panels and with their limited functionality (only direct radiation), are best suited for large scale power operations in the desert and not for rooftops.

Several years ago, Bill Gross of EnergyInnovations proclaimed that his then-working prototype for the Sunflower Solar Collector with a Stirling generator producing 250W would soon go into production, and that prices around 1$/W could be expected after 2004. See his inspiring presentation on http://www.ted.com/index.php/t...nergy.html and more media hype at http://freeenergynews.com/Dire...ndex.html.
What ever happened to those glad tidings? The whole concept seems to have just vanished, replaced by EnergyInnovations' optical condensator PV modules, which still cost between 4-6$/W, and which furthermore are available only for commercial solar generating plants in arrays of 2,000 modules or more, that's 500 kW for 2.5 million $. Consumers are left out in the cold.
The combination of solar collector and Stirling engine seems too brilliant to just fade away, especially after all that R&D and the attending hype. Has this concept been killed by someone whose interests might be edged out by widespread availability of such a timely technology?

Oops, that second link doesn't seem to be working any longer. Let's try again http://freeenergynews.com/Dire...index.html