Update on two-year performance of 120 kWp concentrator PV systems using multi-junction III–V solar cells and parabolic dish reflective optics

Abstract

Multi-junction III-V solar cells have been in operation for the last two years in several 500X dish concentrator PV systems using reflective optics. The performance monitoring of these CPV systems on a 15-second basis has accumulated a very large amount of data and allowed for analysis of the influence of atmospheric parameters to the system efficiency. Dense array modules are assembled into large receivers of approximately a quarter of square meter in size and with a typical efficiency of 31.7% and power output of 36.5kWf under Standard Operating Conditions (SOC, 1000W/m , AM1.5D, low AOD and 21°C cell temperature). At Normal Operating Cell Temperature (NOCT 53°C), the receiver efficiency and power output become 30% and 35.4kW. The DC efficiency of the dish unit is 24.5% at SOC. More interestingly, the specific Energy Production Rate (EPR) of each dish, being the ratio of the daily energy output and the daily incident direct-beam energy (DNR), was measured. In average, over a two-year period and over four dishes, the EPR was 27.5 m 2 , corresponding to the equivalent aperture of a 100%-efficient solar energy converter.The annualised efficiency of these CPV systems is 21.1%. A new generation of dense array modules have demonstrated efficiency of 36.1 % at 50W/cm 2 and 21°C. Also, a new redesigned optics has recently been implemented on one of the dishes and has demonstrated a significant boost in efficiency, bringing the SOC efficiency to 26.2% and an expected EPR of 30 m 2 . We expect that combining the 2 nd generation modules with the redesigned optics would improve the DC efficiency to 28% at SOC.

Concentrated photovoltaic thermal (CPVT) solar collector systems: Part I – Fundamentals, design considerations and current technologies

“…often require the integration of multiple optical elements. Nonetheless, other solar concentrator optics such as parabolic dish reflectors [137], central Table 5 Tracking requirements and typical concentrators corresponding to different concentration levels. receiver systems [138], parabolic trough reflectors [139], and compound parabolic concentrators [140] have been successfully integrated into CPV systems.…”

“…54. CPV systems using different concentration mechanisms including (a) Fresnel lenses [88], (b) parabolic trough [88], (c) parabolic dish [137], (d) compound parabolic concentrators [140], and (e) heliostat field central receiver [138]. [163] and (b) a dynamic mechanism [165].…”

High‐Concentration, III–V Multijunction Solar Cells

“…Field testing, though slower, is the ultimate test. Multijunction HCPV systems have demonstrated 2 -year operation without appreciable degradation [18] . As further test cycles are completed and more systems are deployed in the fi eld, the necessary conditions to ensure a 25 -year lifetime will be established.…”

World's first demonstration of a 140kWp Heliostat Concentrator PV (HCPV) system

“…Since their installation, the performance of these CPV units has been continuously monitored and data have been gathered every 15 seconds. Among these 23 dishes, 16 were originally fitted with highefficiency silicon solar cells and were progressively upgraded with receivers containing multijunction solar cells, boosting the efficiency by more than 56% [3]. The exchange of an existing silicon receiver by a multijunction receiver is an easy operation that can be performed with one single person within about 1 hour of time, resulting in a significant boost of performance that clearly justifies the cost of the upgrade.…”