A series resistance induced by cell interconnections will lead to a worse TCPMPP of solar modules compared with cells.

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The Swiss start-up Insolight aims to be the first company to commercialize a high-efficiency III-V based low profile micro-CPV product that uses planar micro-tracking to eliminate the need for a tilting solar tracker, allowing rooftop mounting using typical flat-plate hardware, as well diffuse light capture using low cost Si solar cells which cover the area of the back plane not taken up by III-V solar cells. The IES-UPM has made an initial performance evaluation of a 0.1m2 prototype. We show that the integrated planar tracking can reach 55° AOI, show CSTC efficiency near to 30% for III-V output, and demonstrate the diffuse capture and planar tracking capability in a multi-week test campaign at our test site in Madrid. Index Terms-integrated planar tracking, diffuse light collection, micro-concentrator photovoltaics.

The silicon heterojunction (SHJ) technology has already proven its ability to produce high-efficiency devices, and very competitive production costs at the mass production level can be potentially reached by integrating latest developments. In this work, several of such technology developments are presented related to the PECVD and metallization steps. PECVD processes were developed in a large-area reactor, showing excellent thickness uniformity over the full reactor area (< 4%) and state-of-theart passivation level (> 16 ms). Improvements in screen-printing permitted to reduce the finger width down to 40 m. A 21.9% 6-inch busbar-less cell with only 25 mg of Ag was produced, resulting in Ag cost of only 0.22 €cts/Wp. A complete SHJ process for full-area 6-inch cells has been established using industry-compatible processes, with a record efficiency of 22.8% and V oc s above 740 mV (CZ n-type). The use of 4 cm 2 SHJ cells for low-concentration applications was investigated at different illumination levels and temperatures. With optimized front grid designs (Cu electro-plated fingers), efficiencies can be maintained around 20% at 10 suns. Thanks to a temperature-assisted improvement in carrier transport, the cell temperature coefficient improves with illumination, showing even positive values above 35 suns. This suggests a strong potential of SHJ cells for low-concentration PV.

Soiling is the major cause of power loss of photovoltaics (PV) and concentrated solar power (CSP) in desert areas. Electrodynamic cleaning system (EDS) is an automatic and water‐free integrated cleaning system for mirrors or solar panels, which uses pulsed electric fields to remove dust off their surface. The first EDS field test over a long period on PV modules is reported here and shows a clear effect on soiling reduction in real conditions in Saudi Arabia. A total of 458 days of measurements is analyzed, and depending on the considered periods, performance losses due to soiling (soiling rate) can vary from −0.06%/day to −0.41%/day for a reference module, while the relative soiling rate reduction using an EDS can be up to 95.7% with an average of 32.1%. Cost calculations demonstrate an added value of the modules equipped with the EDS between 2.6 and 5.2 ¢/Wp compared with usual cleaning system, which is nearly between 10% and 20% of the module price. In addition, extended indoor tests of various electrode designs of EDS for heliostat dedicated to CSP or PV applications show a high cleaning efficiency of up to 98% with front glass thickness of more than 1 mm. A good specular reflectivity, only 4% lower than the bare reference mirror, is obtained with patterned sputtered silver in a spiral electrode design. High reliability of two types of electrode deposition is demonstrated after 200 cycles between −40°C and +85°C.

The power produced by a photovoltaic module is not simply the sum of the powers of its constituents cells. The difference stems from a number of so-called "cell-to-module" (CTM) gain or loss mechanisms. These are getting more and more attention as improvements in cell efficiency are becoming harder to achieve. This work focuses on two CTM mechanisms: the gain due to the recapture of light hitting the apparent backsheet in the "empty" spaces around the cells and the loss from the serial connection of "mismatched" cells i.e. with different maximum power points. In general, for insulation purposes, the spaces on the edges of modules are larger than the spacing between cells. This study reveals that, when reflective backsheets are used, these "edge spaces" provide an additional current boost to the cells placed at the edges that can lead to a 0.5% gain in the output power of modules (with 60 or 72 cells). This location-dependent current boost adds to the usual variations in cell characteristics dictated by the binning size and results in larger "cell-to-cell mismatch losses". However, the simulations reveal that for short-circuit current bin size smaller than 5%, this additional mismatch loss is lower than 0.05%. All considered, this study demonstrates that the spaces at the edges of PV modules have a significant impact on the cell to module ratios (≈+0.5%abs or ≈16% of the CTM gains) when reflective backsheets are used.

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