Solar heat for the shop. ^5's Morris!

[Morris Dovey]

More on this at

[Robatoy]

Soooo.. if I were to put a 4x8 sheet of something...like white melamine in front of this panel, on the ground.......

[Lee Michaels]

Soooo.. if I were to put a 4x8 sheet of something...like white melamine in front of this panel, on the ground.......

*************************

An interesting idea. The material would need to be stable, durable and highly reflective. It would probably need to be washed now and then too. I don't think birds could resist using such a bright surface as a target.

Still....., if this works, it would just improve the numbers on payback, etc.

[Morris Dovey]

By George, I think he's got it!

Heh - how about a little spray adhesive and some aluminum foil on that melamine if you're going to be /really/ greedy?

Or... You could get a dozen 4x8 sheets of rear-silvered polycarbonate mirror material and make your shop really toasty. :-)

See photos at

to see how to produce serious warmth...

[Mark & Juanita]

That looks like a winning cost trade. Thus far, all of the other alternatives like solar electric don't come even close. I did a trade earlier this year and couldn't get the system to even pay for itself over the advertised 25 year life span. That took into account any credits and rebates available and included paying cash for the system (i.e., no interest cost) and not assuming any lost investment value on the cash. What was really ironic was that the company selling the solar system was willing to issue a 30 year note on a system for which they were advertising a 25 year life.

[-MIKE-]

Do you watch Mythbusters? :-)

[Morris Dovey]

I've heard of but never seen (no cable TV). What did they do?

This heat, BTW, is used to run an engine whose only moving parts are air and water (in keeping with my fondness for keeping things as simple as possible).

[dpb]

...

We're beef not, dairy so I don't have a clue of what you think a milk-house heater on "High" BTU output is... :)

I don't give a patootie about really accurate, I was just looking for ballpark sizing guesstimates.

So, iiuc, this is relying on ground reflection not direct solar? The thoughts I had were more for hayloft.

The point about tight is a good one--that's a real issue for the barn which is why the free fuel source is attractive--if it could at least knock of the worst in an area w/ some internal baffling to reduce the draft it would be more than have presently.

--

[Morris Dovey]

Solar thermal can be awesomely efficient and solar photovoltaics offered on the consumer market (as opposed to those made for aerospace applications) have energy conversion efficiencies of only 10-15%.

I've been working to develop a couple of fluidynes (Stirling cycle heat engines) capable of converting sunlight directly to mechanical energy. These have a theoretical maximum efficiency of only about 55% - and I don't expect to do better than 25-30% with my design but, still, they'll be a lot more efficient than using PV panel to charge a battery which is then used to run a motor (with losses at each conversion).

OTOH, direct solar doesn't work very well at night...

[-MIKE-]

They did an episode on Archimedes' Death Ray, which purportedly was used to burn up attacking ships out in the sea. Thousands of solders holding mirrors pointing at a ship.... phhhhhew, it bursts into flames.... so legend has it.

Some of their "experiments" closly resembled your parabolic. I'm guessing a youtube search could yield both episodes in their entirety. Although I'm guessing there would be a lot of, "Nooooooo," and "That's not how you do it," coming from your lips. :-)

I'm really enjoying reading your info. Ever work with geothermal? Not volcanic steam they get in Greenland, but piping buried underground to get the constant 55 degree temp.

[Morris Dovey]

Yuppers, I'd read about that. I've heard that references have been found to a description of a steam engine in the Library at Al Iskanderia.

Yeah, I'll admit to being at least that much a geek. Isn't it amazing just how little of all this technology is actually /new/?

I haven't, but here's a bit of native Iowa geothermal technology:

gentleman whose shop you looked at has one of these and added horizontal plastic pipe runs at the bottom for a bit of added heat. He introduced me to the guy who came up with the stock waterers, and I can vouch for him being a good guy to do business with (blatant plug).

[dpb]

Morris Dovey wrote: ...

I'd be most interested in that, too, Morris...

--

[Morris Dovey]

Here it comes 'round again:

[dpb]

... Oh, sorry...I thought that was an indirect connection referred to.

I'm on way out of town; will check at some more length later on.

Am still curious about the approximate Btu panel output, though...

--

[Morris Dovey]

Oops - sorry. Usually 1300 - 1500 Watts.

Ballpark without reflection as above. Reflected energy is a variable bonus in addition to that.

The panels will certainly add heat, but warm air rises and is guaranteed to find any upward path to the outdoors. If you have a specific area you'd like to heat, then a bit of framing to support insulation and some plastic film might provide a way to retain much of the heat...

[BDBConstruction]

I would say you got in concert with a goof troop of a AE company or you made some grave miscalculations. The data out there is pretty well established as to payback of well designed and well located AE systems. While in many areas they can be markedly less cost effective none I have seen have a 30 year payback even in states with no rebates. I would have to think something in your calculations was incorrect or your system was overblown, poorly designed, etc. This wouldnt surprise me in the least as when capitalist greed gets involved installers usually pork up the system and install.

Most simple calculators available on line that take into consideration generating 75% of your residential power and a modest 6% annual increase in energy costs will show that an average house with a $75/mo electric bill will save some 30,000-40,000 dollars over the 20 year life of a 9-11k system. In many states this system will cost 3-4k out of pocket and less if you can do any of the install yourself.

Of course all calculations are speculative in that none of is know where the cost of energy is going in the next 25 years. If we can keep scaring OPEC over the loss of their cash cow we may be able to hold their feet to the fire keeping petro low. Have heard two or three times on the news here lately that some project if this low stays low we could again see 1.00 gasoline though it would of course be unsustainable. These low costs will, and are there to, thwart AE in any form. It is actually quite sad when we need to be forced to innovate.

Mark

[Mark & Juanita]

... snip

.. snip

First, 6% is hardly a modest annual increase in annual energy costs and is not born out historically. Checking to determine whether it would be cost effective to change out my old heat pump for a newer, more efficient one, I checked my electric use for the past 10 years -- energy costs have not increased by that much on average. A more realistic average is closer to

3% per year.

However, starting with your estimate of $75 over 20 years with 6% increases, one gets the following:

Year Per month Per Year Cumulative 75% Savings Cum savings

1 $75 $900 $900 $675 $675 2 $80 $954 $1,854 $716 $1,391 3 $84 $1,011 $2,865 $758 $2,149 4 $89 $1,072 $3,937 $804 $2,953 5 $95 $1,136 $5,073 $852 $3,805 6 $100 $1,204 $6,278 $903 $4,708 7 $106 $1,277 $7,554 $958 $5,666 8 $113 $1,353 $8,908 $1,015 $6,681 9 $120 $1,434 $10,342 $1,076 $7,757 10 $127 $1,521 $11,863 $1,140 $8,897 11 $134 $1,612 $13,474 $1,209 $10,106 12 $142 $1,708 $15,183 $1,281 $11,387 13 $151 $1,811 $16,994 $1,358 $12,745 14 $160 $1,920 $18,914 $1,440 $14,185 15 $170 $2,035 $20,948 $1,526 $15,711 16 $180 $2,157 $23,105 $1,618 $17,329 17 $191 $2,286 $25,392 $1,715 $19,044 18 $202 $2,423 $27,815 $1,818 $20,861 19 $214 $2,569 $30,384 $1,927 $22,788 20 $227 $2,723 $33,107 $2,042 $24,830

However, applying the more realistic 3% increase: Year Per month Per Year Cumulative 75% Savings Cum savings

1 $75 $900 $900 $675 $675 2 $77 $927 $1,827 $695 $1,370 3 $80 $955 $2,782 $716 $2,086 4 $82 $983 $3,765 $738 $2,824 5 $84 $1,013 $4,778 $760 $3,584 6 $87 $1,043 $5,822 $783 $4,366 7 $90 $1,075 $6,896 $806 $5,172 8 $92 $1,107 $8,003 $830 $6,002 9 $95 $1,140 $9,143 $855 $6,857 10 $98 $1,174 $10,317 $881 $7,738 11 $101 $1,210 $11,527 $907 $8,645 12 $104 $1,246 $12,773 $934 $9,580 13 $107 $1,283 $14,056 $962 $10,542 14 $110 $1,322 $15,378 $991 $11,533 15 $113 $1,361 $16,739 $1,021 $12,554 16 $117 $1,402 $18,141 $1,052 $13,606 17 $120 $1,444 $19,585 $1,083 $14,689 18 $124 $1,488 $21,073 $1,116 $15,805 19 $128 $1,532 $22,605 $1,149 $16,954 20 $132 $1,578 $24,183 $1,184 $18,138

Now, that is still respectable and would provide a return on investment beginning in the 6'th year as long as maintenance is not required. However, I would expect some maintenance in terms of batteries or other storage devices required to achieve the stated 75% savings since one must be able to get some of that savings at night. If you are relying upon selling the energy back to the electric company at a 1 for 1 trade to serve as your storage system, one can't rely on that in the out years if more people start using this approach.

The systems I saw for solar electric sufficient for home electric generation were on the order of $60k, vs the $3 to $4k you indicate.

The 10 year average I used should be fairly applicable since it began at a period when gas prices were below $1 and have carried through this year's $4+ prices. The fly in the ointment in the future will be if this cap and trade taxation scheme ever gets implemented and destroys the cost of electric power.

[Mark & Juanita]

If you can get the efficiency up there and turn an alternator, you may have something

No, but if you can get the effiecencies a bit above what you are thinking, one can either charge batteries or sell back to the electric company. Right now, a lot of places they do 1 for 1, in the future I would expect that to change to more like 2 for 1 cost to buy-back ratio. Still that might be a good trade for having to buy and replace a battery farm.

[Morris Dovey]

I figure I'll have something as soon as I can get these things to irrigate the first million acres of marginal cropland through a dry season.

My first priority is availability, rather than efficiency. As with many engines and motors, the first increment of efficiency is almost free and the final increment defines unaffordability.

I'm taking the lazy man's way out by trying to solve the easy problem first... :)

[Mike O.]

There was an interesting article in the Nov PM mag about an Arizona company named Stirling Energy Systems. They're testing a 38' wide dish powering a 25KW Stirling engine that heats and cools hydrogen gas. They claim to have set an efficiency record for a commercial solar device at 31.25 %.

After reading that, I'm wondering how many mirrors I can glue to my neighbor's old 6' satellite dish.

Mike O.