High Concentration PV

Current Practice

FIG. 1.1 Array of Silicon Solar Panels: simple, flat, 100% area filling but also having limited efficiency.

Field Array Articulated Panel

FIG. 1.2 Wasted Land. Array of Tracking Concentrating Panels: less than 50% area coverage but also having more than 2x the efficiency of Silicon solar cells.

The basic idea behind Concentrating PV (CPV) is to concentrate the sunlight onto a smaller area of photovoltaic material in order to reduce the amount of photovoltaic material needed in a solar panel. Roughly speaking, low concentration systems (LCPV) concentrate the sunlight by a factor of 1x to 100x, do not require precision trackers, and typically use silicon photovoltaic cells.

Conversely, High Concentration PV (HCPV) systems concentrate the sunlight by a factor of 100x to 1000x (and higher) and must use precision tracking of the Sun to reach these high concentration levels. However, HCPV systems reduce the area of photovoltaic material used in a solar panel so drastically that it becomes cost effective to use exotic and higher efficiency PV technologies—such as triple-junction solar cells. Currently, HCPV solar cells have a conversion efficiency of around 40%, with a maximum theoretical conversion efficiency of around 64%, compared to about 20% for best-of-class SiPV cells.

BEST & WORST features of SiPV & HCPV:

Best Features of Current SiPV
a. 100% coverage of the collecting area (no gaps);
b. No need for large-scale mechanical trackers;
c. Easy to clean / low maintenance costs.

Worst Features of Current SiPV
a. Conversion efficiency limited to about 20%;
b. Large amounts of PV material required;
c. Area efficiency goes down when used in a tracking array.

Best Features of Current HCPV
a. Conversion efficiency is already 40%;
b. Conversion efficiency may yet increase (up to 64% limit);
c. Ultra-High efficiency (>64%) might be possible (SUPERcell);
d. Uses minimal amount of PV material;
e. Tracking the Sun's rays maximizes insolation.

Worst Features of Current HCPV
a. Fills less than 50% area to aviod shadowing & collisions;
b. Large mechanical trackers waste a large amount of area;
c. Large mechanical trackers waste material resources;
d. Dead space between panels kills 40% efficiency advantage.