Excess solar flux could be harnessed and used to generate additional electricity at a tower CSP plant, by cladding part of the tower containing the receiver with photovoltaic (PV) panels, according to Sandia scientist Cliff Ho. He found that adding PV on the tower could generate over 10 MW, or 10% of the total capacity of a 100 MW CSP plant, using the same reflected sunlight off heliostats used to focus “suns” up onto the tower receiver for thermal solar generation.
Excess solar flux could be harnessed and used to generate additional electricity at a tower CSP plant, by cladding part of the tower containing the receiver with photovoltaic (PV) panels, according to Sandia scientist Cliff Ho. He found that adding PV on the tower could generate over 10 MW, or 10% of the total capacity of a 100 MW CSP plant, using the same reflected sunlight off heliostats used to focus “suns” up onto the tower receiver for thermal solar generation.
One use for additional direct electric power from PV would be to supply onsite energy needs. So called “parasitic” needs include powering pumps and the electronic drives on the heliostats that move them into the various aiming positions needed throughout the day and night. Parasitic needs can consume as much as 15% of total capacity.
The concept, developed at the United States Department of Energy’s Sandia National Laboratories would utilize the solar flux created when heliostats are not directly focused on the receiver. In a standby position, the heliostats must be focused nearby, so they can be re-aimed quickly onto the receiver when generation is needed. Even mirrors aimed at the receiver can also be slightly off target, just as a result of surface aberrations, misalignment, and tracking errors in heliostats.
“You can actually have on the order of ten to a hundred kilowatts of energy per square meter spilling outside of the receiver,” Ho told an Emerging Concepts audience at the 23rd SolarPACES Conference in Santiago, Chile. “The objectives in this work are to look at the concept of using photovoltaic modules to convert that spillage of otherwise wasted energy to electricity.”
Read more at SolarPACES
Image: At Ivanpah (shown) an estimated 1,000 square meters of heat shield area (white: above and below the receiver) would be available to accommodate PV on the heat shield area of each of its three towers. (Credit: Argonne National Laboratory: Ivanpah solar flux measurement)
