Cold shop?

[Morris Dovey]

For anyone thinking of adding a bit of solar heat to their shop, I've put up a web page (link below) with monthly maps showing how much solar energy is delivered to locations in the USA. The data represents a 30-year average.

If you're not in the USA, you may be able to find that information at

At the bottom of the page there's a link that can be used in conjunction with the map data to predict the heat output from a south-facing vertical panel. The program will run under Windows or MS-DOS (apologies to others; but this is a Windows box).

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[Leon]

Morris, do you have one for cooling the shop? ;~)

[Markem]

The Ice Man Cometh with a fan. :)

Mark (sixoneeight) = 618

[Patriarch]

"Morris Dovey" wrote in news:45a39b84$0$508$815e3792 @news.qwest.net:

It's still early in the morning, but I'm having a bit of a challenge processing this data.

The map seems to indicate that, for example, southern Arizona has more heating potential in December than in August. And that the SF Bay area seems pretty close to the same number all year.

Am I reading this correctly? Is this 'sun angle'?

Patriarch, off to work...

[Tyke]

I have the same interpretation problem.

I have two 4x8ft solar panels for heating domestic potable water. Installed in mid 80's. I know the relative heat gain over the months.

The colours make sense for my location SE PA, but the legend does not make sense.

According to the legend, my location has less heat gain in April/May than March. Does not happen this way for me.

Dave Paine.

[Morris Dovey]

| Morris, do you have one for cooling the shop? ;~)

I'm so glad you asked!

Take a look at

- one of my leisure-time play group activities looks like it'll result in a solar-powered air-conditioner...

You may also want to cool your house, too. How does a zero operating cost strike you?

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[Morris Dovey]

| The map seems to indicate that, for example, southern Arizona has | more heating potential in December than in August. And that the SF | Bay area seems pretty close to the same number all year. | | Am I reading this correctly? Is this 'sun angle'?

Yup. Note that this data is for _vertical_ panels. When the sun is high overhead during the summer, it "sees" much less capture area. In winter the sun is much lower and "sees" a much greater capture area.

Not accounted for in the map data is a significant increase in reflected radiation during winter months - as much as a 95% increase is possible from clean snow...

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[Morris Dovey]

Tyke wrote: | I have the same interpretation problem. | | I have two 4x8ft solar panels for heating domestic potable water. | Installed in mid 80's. I know the relative heat gain over the | months. | | The colours make sense for my location SE PA, but the legend does | not make sense. | | According to the legend, my location has less heat gain in | April/May than March. Does not happen this way for me.

I'd guess that your DHW panels aren't vertical (vertical is best for winter heat only). Since we want hot water year-round, DHW panels are more likely to be set at an angle that works most efficiently at vernal and autumnal equinox angles.

How's my guess?

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[Tyke]

Good guess. I read "Vertical" but did not think about how this affected performance. This makes sense now.

My latitude is 41.5 deg N. I installed the panels at about 45 deg to give slightly better performance in winter. I can get TOO much gain in summer if water use is low.

Dave Pa> | I have the same interpretation problem.

[Morris Dovey]

| Good guess. I read "Vertical" but did not think about how this | affected performance. This makes sense now.

Most of us aren't used to thinking of seasons in geometric terms. Since the earth's axis of rotation is tilted (approximately) 23.43929 degrees from its orbital plane, there's a difference of almost 47 degrees between summer and winter solstices. That's a big swing.

| My latitude is 41.5 deg N. I installed the panels at about 45 deg | to give slightly better performance in winter. I can get TOO much | gain in summer if water use is low.

Good plan. BTW, NREL also has the same kind of map data available for panels tilted at increments from location latitude. I'd guess that those will better reflect (no pun intended) the behaviors you've experienced.

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[Nova]

Im my area we've found out that solar powered devices require sunlight.

[Mike]

Patriarch wrote in

It's the Earth's tilt that determines seasons, yes.

The Earth is actually closest to the Sun in winter and furthest in summer, but the northern hemisphere is tilted toward the Sun in summer and receives more of those parallel rays and, hence, is warmer.

I have a problem with the maps, too, though. Because not only are solar panels receiving more rays in summer, but the days are also longer. Sounds like a good experiment for me to setup this winter.

Mike

[Morris Dovey]

| Im my area we've found out that solar powered devices require | sunlight.

Yup. Solar or not, it would seem like a good idea to have some kind of backup power arrangement.

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[Morris Dovey]

Mike wrote: | Patriarch wrote in || Am I reading this correctly? Is this 'sun angle'? | | It's the Earth's tilt that determines seasons, yes. | | The Earth is actually closest to the Sun in winter and furthest in | summer, but the northern hemisphere is tilted toward the Sun in | summer and receives more of those parallel rays and, hence, is | warmer.

I wasn't aware that our orbit is eccentric. During winter the atmospheric filter is "deeper" and the sun is behind the horizon longer so that the daily heating period is both weaker and shorter.

| I have a problem with the maps, too, though. Because not only are | solar panels receiving more rays in summer, but the days are also | longer.

The panels would receive more direct radiation in summer if they were horizontal. A vertically-oriented panel actually receives less. Not only that, the glazing on a vertical panel reflects more of the light away during the summer (like a poorly silvered mirror).

| Sounds like a good experiment for me to setup this winter.

It could be interesting.

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[nailshooter41]

All I can say is .... Wow. Thanks for taking the time to put up the site, the pics and the explanation. I know that was a lot of work and I personally found it to be fascinating.

Good work!

Robert

[Patriarch]

"Morris Dovey" wrote in news:45a3b5de$0$502$815e3792 @news.qwest.net:

There's _seldom_ clean snow where we are. Seldom _any_ snow. Heck, I still have some very nice english roses that don't belive it's January right now. Still blooming.

Solar here is an interesting challenge. I'll have to give it more thought over the next week or so, as I'm traveling about. There's panels on the roofs of several of the homes on my block, doing heat gain for their swimming pools. Those folks are happy with them, so there's a start.

Patriarch

[Leon]

Very Cool

[Mike]

"Morris Dovey" wrote in news:45a41c5d$0$503$815e3792 @news.qwest.net:

Kepler's first law of planetary motion: "Each planet revolves around the Sun in an elliptical path, with the Sun occupying one of the foci of the ellipse."

For Earth the eccentricity is tiny, though. Nothing like Pluto's. In fact, I think all orbits have to be eccentric to some degree...only two bodies of the same mass would wind up orbiting the same point equally.

Earth doesn't quite revolve around the Sun. They both revolve around a common point, which resides somewhere _inside_ the Sun, but not at it's center.

According to NASA (an article from 2001):"We make our closest approach to the Sun (147.5 million km) in January, that's called perihelion, and we're farthest from the Sun (152.6 million km) in July, that's aphelion."

I think it's all pretty cool.

Thanks for the update on the positioning of the solar panels.

Mike

[Mark & Juanita]

Keep us apprised of when you get that perfected. My dad has always said there should be a solar air conditioning capability similar to how the old natural gas refrigerators used to work.

ZOC is great as long as initial investment and amortized ownership costs are below what a conventional system would cost. IMO, this is where solar is having problems right now. Sure, I can get panels that would generate enough electricity to run my house amd sell extra back to the grid during times I'm not using it. However, the cost of ownership indicates it would take at least 10 years to reach break-even and I'm not convinced that materials technology is anywhere near having something like that last long enough without repairs to ever pay back. That also assumes no little issues like hailstorms or kids' balls wreaking havoc on the system.

It's been a couple of years since I investigated solar electric panels (an obvious winner in a place like southern Arizona). I think I calculated that electricity would have to reach 25 to 30 cents per KWH to even make the panels close to competitive.

I realize what you are proposing is quite different, and I believe that solar heating has a bit better payoff capability. Really do hope you can perfect the solar A/C approach -- that would be way cool (no pun intended).

+--------------------------------------------------------------------------------+ If you're gonna be dumb, you better be tough +--------------------------------------------------------------------------------+

[Patriarch]

Mark & Juanita wrote in news: [e-mail]:

There are (as always, I guess) some very excited researchers, engineers and manufacturers working in Silicon Valley on systems with much higher reliability, manufacturability and simplicity, and much lower cost structures than have been seen in recent years. I don't have my checkbook out yet, but what seems feasible is a much lower local production cost. One of the benefits to that is a much lower transport infrastructure cost as well, at least for the locally produced power.

There is, I am certain, still a lot to learn in this area. And folks are looking forward to it as well.

Patriarch