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The Solar Sunflower

arstechnica.com

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Re: The Solar Sunflower

#11

Post by danmaz74 »

ScottBurson wrote: post #10
danmaz74 wrote: post #7

While reading the article, I was wondering why combined PV/water heating conventional panels aren't taking off on rooftop installations. Looks like something that would make a lot of sense.

It's a good question. The panels are available, for example these: http://www.solimpeks.com/pv-t-hybrid-solar-collectors/ My guess is they're not as popular because the overall installation complexity is much higher: you have to run the piping, and I'm not even sure exactly what you do with the hot water that comes out. There won't be room for it in your existing hot water heater, so you'll need a second tank, and wh…

Yes I'm sure there is some good reason, but considering that solar for water heating - without PV - has been sold for ages already, there should be a market. Let's hope somebody with a real-world understanding of the problem will answer, I'm really curious :)

Re: The Solar Sunflower

#12

Post by srtjstjsj »

Is the "5,000 suns" part complete marketing BS? The description says that they compress the energy of one sun into 1/5000 the area, to reduce the expense of photovoltaic material. But the process isn't 5000x more efficient at obtaining energy from the sun.

At best, it's "the power of 5000 solar panels", which is a much less exciting headline.

Re: The Solar Sunflower

#13

Post by michaelbuckbee »

ScottBurson wrote: post #10
danmaz74 wrote: post #7

While reading the article, I was wondering why combined PV/water heating conventional panels aren't taking off on rooftop installations. Looks like something that would make a lot of sense.

It's a good question. The panels are available, for example these: http://www.solimpeks.com/pv-t-hybrid-solar-collectors/ My guess is they're not as popular because the overall installation complexity is much higher: you have to run the piping, and I'm not even sure exactly what you do with the hot water that comes out. There won't be room for it in your existing hot water heater, so you'll need a second tank, and wh…

Swimming pools - in areas like the NC Outer Banks - the systems give you an extra month or so of swimming on each end of the season.

Re: The Solar Sunflower

#14

Post by detaro »

ScottBurson wrote: post #10
danmaz74 wrote: post #7

While reading the article, I was wondering why combined PV/water heating conventional panels aren't taking off on rooftop installations. Looks like something that would make a lot of sense.

It's a good question. The panels are available, for example these: http://www.solimpeks.com/pv-t-hybrid-solar-collectors/ My guess is they're not as popular because the overall installation complexity is much higher: you have to run the piping, and I'm not even sure exactly what you do with the hot water that comes out. There won't be room for it in your existing hot water heater, so you'll need a second tank, and wh…

The heating water part is really common here in Germany and not that big of a deal, and not just for new constructions. Basic heat storage/exchange parts often easily fit in existing rooms or even in the space the old heating system took.

You only see either solar cells or heat collectors though.

Why there are no/not many combined setups, no clue. Maybe the efficiency goes down to much and limits the range of regions where it is viable? Maybe there are regulatory issues with water + power systems so close together (driving up installation and maintenance prices).

Re: The Solar Sunflower

#15

Post by dang »

srtjstjsj wrote: post #12

Is the "5,000 suns" part complete marketing BS? The description says that they compress the energy of one sun into 1/5000 the area, to reduce the expense of photovoltaic material. But the process isn't 5000x more efficient at obtaining energy from the sun. At best, it's "the power of 5000 solar panels", which is a much less exciting headline.

We've taken that bit out of the title here.

Re: The Solar Sunflower

#16

Post by Spooky23 »

danmaz74 wrote: post #7

While reading the article, I was wondering why combined PV/water heating conventional panels aren't taking off on rooftop installations. Looks like something that would make a lot of sense.

Most of the new installations are linked to energy leasing vehicles. Water doesn't work there. Also, most folks use gas or propane to heat water, and gas prices are very low.

People spend a lot money in heating water. My folks did a hot solar hot water system in the 90s, and I think that the payback period was something like 3 years.

The system exchanges a fluid (I think glycol, but don't quote me) into a coil in front of the water heater water supply. So instead of dumping cold water in the tank, you're feeding it warm water. With a tankless system, it's even better.

Re: The Solar Sunflower

#17

Post by tinco »

jacquesm wrote: post #3

I take exception to the use of the word 'invention' here because that most likely implies that patents are at stake. Tech such as this has been tried on-and-off by various parties since the 80's, with many variations on geometry, working fluid, actuation and tracking. Parabolic segments are a pretty expensive way to do this because it requires moving the collector around. Much simpler and easier to have a stationary…

The 'invention' part of this setup is not their mirror configuration, which just looks pretty and possibly is easy for them to build and deploy in spaces where space is a problem. You have to admit that it looks good in that sunflower field. Their footprint looks like it's As it says in the article, the actual interesting part is how they generate the energy, apparently with a GaAs that's cooled with some sort of futuristic microfluidic water system. If that works well just the receptor can be a very profitable product, they can let others worry about mirror configurations and deploying in farm lands.

Re: The Solar Sunflower

#18

Post by powertower »

> GaAs is much more efficient at converting sunlight into electricity (38 percent in this case, versus about 20 percent for silicon).

Is that true... You get almost 2 times the power output with GaAs cells then conventional solar cells made from silicone?

Re: The Solar Sunflower

#19

Post by monochromatic »

jacquesm wrote: post #3

I take exception to the use of the word 'invention' here because that most likely implies that patents are at stake. Tech such as this has been tried on-and-off by various parties since the 80's, with many variations on geometry, working fluid, actuation and tracking. Parabolic segments are a pretty expensive way to do this because it requires moving the collector around. Much simpler and easier to have a stationary…

> I take exception to the use of the word 'invention' here because that most likely implies that patents are at stake.

Why shouldn't patents be at stake? Maybe they've come up with something new and non-obvious, or maybe they haven't... we can't exactly tell from this article though.

Re: The Solar Sunflower

#20

Post by tinco »

powertower wrote: post #18

> GaAs is much more efficient at converting sunlight into electricity (38 percent in this case, versus about 20 percent for silicon). Is that true... You get almost 2 times the power output with GaAs cells then conventional solar cells made from silicone?

Yes[0]. Apparently the records lie at 41% for GaAs and 27% for silicon[1] so they're being a little bit loose with the stats, 20% for silicon is consumer grade panel level.

0] https://en.wikipedia.org/wiki/Gallium_arsenide#Solar_cells_a...

1] http://www.pveducation.org/pvcdrom/appendices/solar-cell-eff...

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