Concentrated Photovoltaics, Parabolic Mirrors

[mnmman]

The idea of a parabolic mirror to focus light onto a small solar panel popped into my mind the other day. I searched Google and this is about the best thing I found-
http://www.greenrhinoenergy.com/solar/technologies/pv_concentration.php
and
http://www.aps.com/main/green/Solana/Technology.html

Wouldn't focusing light toward one little panel be way more efficient than the fields of panels that I keep seeing more and more of? It seems to me that the Arizona plant is using the heat from this concentrated light to boil water and turn steam turbines. Good idea but why not instead use the light itself pointed at a photovoltaic cell? Can someone help me make sense of this?

 

[berkeman]

The idea of a parabolic mirror to focus light onto a small solar panel popped into my mind the other day. I searched Google and this is about the best thing I found-
http://www.greenrhinoenergy.com/solar/technologies/pv_concentration.php
and
http://www.aps.com/main/green/Solana/Technology.html

Wouldn't focusing light toward one little panel be way more efficient than the fields of panels that I keep seeing more and more of? It seems to me that the Arizona plant is using the heat from this concentrated light to boil water and turn steam turbines. Good idea but why not instead use the light itself pointed at a photovoltaic cell? Can someone help me make sense of this?

Welcome to the PF.

You could maybe do a 2:1 concentration or so. What issues do you see with doing a higher concentration of sunlight on solar cells? Have you learned about reverse leakage current yet?

 

[Enthalpy]

It was experimented the big scale at Madrid's Complutense university in 1994, with concentration factors >20.

Concentration is one sensible way to use photovoltaics, yes. Not only does it drop the cost of the collecting area, it also raises the cell's efficiency because the higher current density means a higher voltage... BUT this holds as long as you can cool the cells so (1) they don't burn (2) the leakage current stays reasonable.

Some designs put the cells against passive fin coolers in air. Others let a cooling liquid circulate.

An other avantage: as the cell area drops, you can afford more costly technology, like monocrystalline silicon, or GaAs, InP... which are more efficient.

 

[mnmman]

Welcome to the PF.

You could maybe do a 2:1 concentration or so. What issues do you see with doing a higher concentration of sunlight on solar cells? Have you learned about reverse leakage current yet?

I don't see any issues, other than what Enthalpy said, but I don't know much about electricity. I understand what leakage current is, but can't make sense of reverse leakage current.

 

[Bobbywhy]

mnmman, Welcome to Physics Forums!

Here is a description of two large large photovoltaic concentrator power systems:

Photovoltaic concentrator technology development:
Description/Abstract
This paper summarizes the progress that has been made in the past 18 months in the area of photovoltaic concentrator technology development. A brief description of the status of two new photovoltaic concentrator power systems, the 300 kW ENTECH-3M-Austin system, and the single-pedestal Alpha Solarco system is given.
http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=6909974

Here is an excellent review of many types of concentrators:

http://www.google.com/url?sa=t&rct=...ps3ZnU6QBepTj1sEw&sig2=co1U4TiE6EGUpFxLSuz1Qw

 

[mnmman]

thanks for all the replies, looks like I got a lot to learn.