Submitted by galileofan t3_1249o2a in Futurology
Comments
KikeRC86 t1_jdyye44 wrote
This is not entirely clear in the article. So they use solar heating for, for example, hot water while using the PV for energy production? It’s not a bad idea, the water cools down the PV so they’re kinda killing two birds with one stone.
Sirisian t1_jdz1i7x wrote
Interesting. So if you had a bunch of these and used like a 35% efficient steam turbine without any other losses in the piping that's 20% + 35% * 60% = 41%. That seems extremely high though, so it seems wrong to me. That would match some of the most expensive solar panels used for satellites.
JeremiahBoogle t1_jdz57nt wrote
I think it would be meant for solar water heating in the house, it won't be hot enough to drive a steam turbine.
No_Opposite_4334 t1_jdzjlw4 wrote
What if a liquid (e.g. acetone) with a lower boiling point (57C for acetone) is used?
RedditorsArGrb t1_jdzlqn9 wrote
small temperature gradient means low efficiency in a heat engine. See: https://en.wikipedia.org/wiki/Carnot_cycle#The_Carnot_cycle
A "35% efficient steam [system]" is not a physical reality here.
SandAndAlum t1_je4owx4 wrote
Working at a high enough temperature to make an efficient heat engine run would almost certainly make the PV performance worse or destroy it.
This will be low grade heat for space or water heating. Possibly applicable to chemic process or electrolysis too (heat can reduce the electricity needed to just splitting the molecule). Might be able to use the electricity to upgrade the heat using a heat pump for chemical use, although you're unlikely to beat a heliostat which is much simpler.
[deleted] t1_jdzwry9 wrote
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[deleted] t1_je1la0z wrote
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WaitformeBumblebee t1_je1ur9g wrote
Welcome to reddit
kryptylomese t1_jdzub0x wrote
er... but it is often hot when it is sunny, so there is less of a requirement to heat your home.
FuturologyBot t1_jdyjqjm wrote
The following submission statement was provided by /u/galileofan:
80% from where we are now seems hard to believe.
Please reply to OP's comment here: https://old.reddit.com/r/Futurology/comments/1249o2a/german_manufacturer_achieves_80_overall/jdyfoo2/
[deleted] t1_jdynmfd wrote
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Bragisson t1_jdynrz6 wrote
80% efficiency is absolutely huge compared to the common 25%. To extract that much energy from the sun is revolutionary. I wonder the costs.
AJ_Gaming125 t1_jdyxocj wrote
Other guy said it was only 20 percent electrical output, the rest is just heat output
MightyH20 t1_je4c7bs wrote
Heat output can be used to provide heating or complement heatpumps. It is de facto an energy flow to be applied in homes thereby allowing a certain amount of energy to be used, otherwise wasted.
galileofan OP t1_jdyfoo2 wrote
80% from where we are now seems hard to believe.
elixier t1_jdzgxpu wrote
Yeah because that figure is massively misleading
WaitformeBumblebee t1_jdzh0b7 wrote
e+th, but pretty nice if they can keep the price low
pickingnamesishard69 t1_je1knx9 wrote
Not just pretty nice but absolutely necessary. Until now you could heat water with the e from panels, thus losing 30-60% of your production. Using the thermal directly means you can heat more water than a single family home can use. Stuff like this can heat water for blocks AND bring electricity.
Was just a matter of time until companies jump onto that otherwise lost energy.
WaitformeBumblebee t1_je1uham wrote
If the price and maintenance is right, otherwise cheap and maintenance free solar pv + heat pump will outperform this. Solar thermal panels are a maintenance headache, but perhaps these will work better by not getting too hot, they still have to make it robust to freezing temperature problems.
SandAndAlum t1_je4p5k6 wrote
Roof space hasn't really been limited until recently (price now makes it kinda viable). Separate solar thermal and PV have been a thing for a while now.
pickingnamesishard69 t1_je4ukgn wrote
The thing with seperate thermal and PV is that you still have thermal energy on the PV that is getting wasted. On top of that, PV panels lose efficiency and degrade faster the hotter they get. Using that extra heat therefore makes double sense, provided (like someone else mentioned) that the extra maintenance is not too costly.
SandAndAlum t1_je4v4xi wrote
All true. The general principle is neat and becomes more relevant as PV gets cheaper. Combine with a thermal store, feed the AC waste heat in too, and suddenly you've gotten rid of seasonal variability in temperate zones.
Couple things in the article make it sound a little sketchy though. If the PV module remains at 30C then how hot is the working fluid? Do they take out the below-bandgap energy before it hits the silicon or is the module hotter than the fluid?
pickingnamesishard69 t1_je6kko2 wrote
Tbh i started talking before i read the article, so no clue about the working temperature. There are multiple concepts floating around afaik - using air/gas is neat because it wont freeze, some liquids might be more efficient but require more maintenance and have higher leaking risks... The one i saw a vid on was working with very cold gas that would get heated to maybe 30-50, would then be cooled via heatpump and repeat. Guess it makes sense to both send the medium cold so it doesnt heat too much, and have pipes that can handle heat (they would need to manage max heat if at any moment the system cant pump)
But: dunno, still didnt read on this one. The concept itself is 100% sound and worthwhile imo, but the question of HOW will have to be solved by engineers.
Most likely multiple paths that work in different conditions.
Particular-Lake5856 t1_jdysg60 wrote
Its only 20% electrical output, about the industry standart.
The rest is Thermal output, they combined solar electricity and solar heat in one pannel.