In the high concentrator photovoltaic (HCPV) systems with solar concentration ratios up to 2000
Suns, significant heat is generated in the used solar cell layer. This high generated heat requires
an efficient and smart cooling technique to keep it operating at a safe operating temperature. In
this paper, another ultra-high concentrator photovoltaic (UHCPV) system with a smaller cell area
of 1 mm2 operating at a high solar concentration ratio (CR) up to 10,000 Suns is proposed. This
smaller area requires a simple passive cooling technique even at high CR. The optimal dimensions
of a passive cooling method using heat spreader are defined. A 3D thermal model for the multijunction
solar cell with the heat spreader coupled with the multi-objective genetic optimization
algorithm is used to define the optimal heat spreader dimensions . The model is validated with the
results in the literature. The model is used to estimate the cell temperature generated electric
power, and cell efficiency at different wind speed, ambient temperature, solar radiation, heat
spreader length, thickness, and CR. The heat spreader dimensions were optimized for CR = 6000
suns, the optimal thickness and length were 2 mm and a of 47.5 mm, respectively. These dimensions
are enough for the safe operation of the UHCPV at CR of 6000 Suns. As a case study, for
a UHCPV module with a total number of cells of 10 by 10, the generated power is around 319 W
at CR of 10,000 Suns. At the same condition, the monocrystalline silicon solar cell in the PERSEID
SOLAR company can generate a maximum power of 144.9 W/m2. For the same area, for the UHCPV module, the generated electric power is around 319 W for 1 m2 of the module. Therefore,
around 120% increase in the power can be accomplished with the use of the UHCPV module. In
the UHCPV module, the total area of the cell is around 1 cm by 1 cm. Therefore, the module cost
could be very low.