Friday, March 6, 2009

How much is 1% in efficiency worth in Solar?

Ok, so say you start with a Solar Panel that's 15% efficient (like today's low-end Crystalline Silicon Panels). For simplicity's sake, lets say that the panel has an area of 1 M^2.

So, at 1000W/m^2 Insolation, the panel will produce 150W, so this would be called its Peak Power Rating.

Let's say that you set that panel in an area with an Insolation Ratio of 20%.

In one year, that panel will produce 30W*Year = 262.8kWh [150W * .20 * 1Year * 365 Days/Year * 24 Hours/Day]



Now, say that the solar panel is 16% efficient.

At 1000W/m^2, the panel will produce 160W, so this is its peak rating.

You set that panel in an area with an Insolation Ratio of 20%.

In one year, that panel will produce 32W*Year = 280.3kWh



What is the percentage difference in the Energy Produced by the two panels in one year?


280.3kWh/262.8kWh = 1.067, so the 16% efficient panel will produce 6.7% more energy in a year than a 15% efficient panel.



Now, say that the solar panel is 22% efficient.

At 1000W/m^2, the panel will produce 220W, so this is its peak rating.

You set that panel in an area with an Insolation Ratio of 20%.

In one year, that panel will produce 44W*Year = 385.44kWh

This panel prouces 46.7% more energy in a year than the 15% panel.


See http://spreadsheets.google.com/pub?key=pNlmSU6te4mhtvbGWKl6KCA for a Spreadsheet that shows the interesting, but maybe obvious results.


So, let's say I have a choice between a 14% Module and a 15% Module. Well, the 15% module produces 7.14% more Energy per year than the 14% one. So, I had better look at the prices, and if the 15% module is more that 7.14% more costly, then you're better off sticking with the 14% one. This is assuming that space, quality, etc, aren't factors, of course. This is "all things being the same."

What if I has a choice between a 45% module and a 46% module? Well, the 46% Efficient Panel will produce just 2.22% more Energy per year than the 45% Efficient one. So, once again assuming that space isn't a factor, the 46% efficient panel had better be no more than 2.22% more costly.


I'm thinking that this is something that manufacturers have to be thinking about, too. Of course, there could be marketing reasons why a panel of a higher percentage efficiency might sell for more, and there are certainly applications that put surface area at a premium, but from a basic cost perspective at the very least, if a manufacturer of 50% efficient modules thinks that they have some technology that will take that efficiency up to 51%, then they'd better be able to manufacture those panels for less than 2% more than it costs them to make their 50% Modules. If the additional materials and manufacturing operations are going to add more than 2% to the cost of manufacture, then they very well might not have gained anything by the "breakthough."


As usual, if my thinking is wrong, by all means, let me have it.



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3 comments:

home wind turbines said...

The sun is a gift from God, that we really need.
It is indeed amazing that we can make use of it's heat. To have energy for our homes and appliances and of course, to save! Solar energy panels really helped many people. It is very useful and reasonable in saving money.

BrightSpot said...

Your result of 6.7% more efficient didn't require the detailed calculations you did. An improvement of 1 on 15 is = 1/15= 6.7%. That's it, that's all.

An improvment of 1 on 40 is comparitively less 1/40=2.5%

D Pickard said...

Haha! Yeah, I realized that after the fact, but I figured there was no harm in keeping up the (over)thinking on it. :)