Ann: CPV Major Milestone - First Commercial Demonstrator Project, page-121

Your comment above is an improvement, you are correct in saying that they won't get the peak rate all day (or ever, most likely - see below). I'll provide clarifications for others below. This is going to be a science-heavy explanatory post, so for those not interested in learning how these panels work, you should probably skip!

(For the rest of this comment, I'll assume we are talking about a square meter panel, and that Clearvue's claim of 30w/sqm is peak power rating. This is largely immaterial though.)

1. The panels are not 30 watt hours, they are 30 watt. This is a big difference.
2. The panel can produce a sustained 30 watts only under optimum conditions. Which is extremely rare in real world applications.

Lets explore the above points further:

The peak power rating of 30 watts is essentially saying "In optimum conditions, a panel can produce energy at a rate of 30 joules per second". This will generally be tested in a laboratory setting, using an artificial light source directly over the panel such that incident light falls perpendicular to the center of the panel.

In reality, the sun will be passing over the panels at different angles. If the glass is positioned well, there will be a point in each day such that the sun will be at an optimum angle to recreate those optimum lab conditions. The rest of the day will see a vastly decreased energy production rate.

However this will also only be at one time of the year. This is how traditional PV panels are oriented/angled - to achieve peak performance during Summer. At other times of the year the panel will produce much less energy - even at the peak point of each day!

This leads to another point to consider - that traditional PV panels can be installed at an angle such that they maximise energy output. Some even rotate during the day to track the sun as it moves across the sky, resulting in incident light that is always perpendicular to the panel. However, with glass panels (as opposed to traditional PV), there will generally be very little choice in the angle they are arranged at; they form part of the building structure so it's generally up to the architect to determine how the glass is laid out. Additionally, the glass can't track the sun for obvious reasons.


The main point of the above is that currently it is very difficult to assess the power output of these panels with any degree of accuracy. I'd be very interested to see some tabulated data from the demonstration project - if it is available please let me know. One thing that can be said for sure, is that unlike traditional PV panels, the limitations of the PV glass in regards to orientation/positioning will generally make it very difficult to ever achieve the peak power output that the panels are rated for.