The commitment of concentrated photovoltaic (CPV) to reduce the cost of solar power generation through high efficiency and moderate cost has been challenged by the recent cessation of activities of many CPV participants. This commercial failure is in sharp contrast to the technical success achieved in this field, and the efficiency of the module is close to 40%. However, despite the fast learning speed, the price of CPV system is still much higher than that of flat panel system, which is expected to reduce from the current US $2.8/w to the target price of US $1 / W when approaching the installed capacity of 10 GW. Due to insufficient demand and investor fatigue, it is unlikely to achieve the large capital investment required for this growing capacity today. Alternatively, costs can be reduced by developing unconventional new module architectures and / or drawing on the experience of industries using similar manufacturing processes. Micro CPV is one of these alternative methods, which has been explored for many years. High tech companies such as semprius and Panasonic have achieved module efficiency of about 35%. In the authoritative paper "road map of light energy conversion", this micro CPV method is described as "an attractive new method". Table 1 lists some recent miniature CPV prototypes.
The idea behind the micro CPV is to reduce the battery size to the submillimeter range for a wide range of benefits at the cost of introducing some manufacturing challenges associated with small battery size and increased number of cells. Micro CPV reduces the volume of CPV modules because their thickness, weight and volume are proportional to the battery size - the battery size is 400 μ M side and 1000x, f / 1.4 condensing optics, module width reduced to 2 cm. Therefore, the weight and shape factors of similar plates are possible, which simplifies the operation, avoids the transportation of empty containers and reduces the energy footprint. In addition, since less heat is concentrated on each battery, resulting in a more uniform heat distribution on the backplane, the battery temperature is reduced. In addition, the reduced thickness increases the contribution of the front to heat dissipation (e.g. in a flat plate). Therefore, it is possible to use an alternative low-cost substrate (such as PCB) without any radiator and reduce the thermal stress on the attachment of solar cells and chips. Similarly, the current generated by each battery is much lower, so the following advantages can be used to reduce the series resistance loss Greater degrees of freedom for series / parallel interconnection (very high voltage modules are possible).
In addition, due to the very short current path involved, the series resistance loss caused by any optical heterogeneity on the solar cell may be significantly reduced. This low effect of thin layer resistance opens the way for replacing low-cost electrical contacts, such as transparent conductive layers. Sandia labs presented a cost study that predicted a peak of $0.50/watt when using 25% efficiency solar cells and 100x solar focusing. Sandia's more detailed research shows that it is indeed possible to predict the cost, and even use batteries with an efficiency of 40-50% to reduce the cost. The compromise of optical devices must be considered, which will lead to the increase of production cost with the increase of concentration.