At Intersolar Europe 2018 in late June in Munich, TaiyangNews moderated during the ‘Next Generation Solution of Solar Renewables and Energy Storage’ a panel on ‘Mono PERC & Bifacial – The Next Big Thing in Solar.’

In his keynote presentation, TaiyangNews managing director Michael Schmela tried to answer ‘Why Mono Bifacial Module Technology is the Next Big Thing in Solar?’ His answer was pretty clear, when he pointed to the newly released TaiyangNews Bifacial Solar Technology Report 2018. ‘Advanced high-efficiency solar cell technologies are basically all naturally bifacial, which allows power generation on both sides of the solar cell at almost no extra cost,’ he said, adding ‘A 5 to 30% gain in output promises a step change in LCOE reduction, which will result in a much faster adoption of bifacial technology than most people think.’

While Schmela discussed the pros & cons for the different cell technologies, he concluded, ‘With PERC having already conquered the mono space, going bifacial is not a big deal on cell and module level – and it is happening.’

 LONGi Solar’s director of product marketing Hongbin Fang, explained why he believes that ‘Mono PERC is the Better LCOE Solution.’ First of all, Fang emphasized that a mono wafer simply offers the better quality material than multi, which results in higher cell efficiencies. Combined with drastically reduced mono wafer manufacturing costs in the last few years there is only upside using mono PERC, he added. Higher power densities lead to balance-of-system and total system cost savings, the technology shows better energy yields and slower power degradation, which results in what everyone is looking for – lower LCOEs.

LONGi’s April 2017 Hi-MO2 bifacial mono PERC module series with over 300W for a 60-cell panel has shown in a field test a 14.3% higher yield compared to standard multi modules with both crystalline varieties being mounted on trackers. This year, LONGi has introduced its new Hi-MO3 bifacial mono PERC module, which is based on half-cut cells that due to reduced resistivity losses increase module power ratings by 5-10 W. The new 60-cell equivalent panel (120 half cells) has a power rating of 320 W and a bifaciality of over 75%.

Half cells are one way to improve module power ratings, but there are many more methods to tweak the cell-to-module efficiency, as presented by Harry Wirth, division head PV modules and power plants at Fraunhofer ISE. With the module cost share in total system cost having dramatically declined, a strong lever has been created to improve efficiencies on the cell and module level as well as performance ratio. And that’s why today the proper focus must be system yield and not module STC power anymore, Wirth emphasized, which in return means a move to bifacial technology.

There are, however, some teething troubles that need to be overcome before bifacial can fully tap its potential. A missing common testing standard is one of these issues. Markus Schweiger, team leader performance and analytics at TÜV Rheinland noted in his presentation that the stated power rating of bifacial PV modules on the market is often inconsistent, while bifacial coefficients of PV manufacturers vary significantly. Moreover, the advantage in energy yield performance depends strongly on site-specific conditions. Schweiger asked for stabilization procedures, reliability and qualification testing to be adopted. While an IEC testing standard is anticipated to be published in 2019, TÜV Rheinland has its bifacial standard test conditions up and running and will even issue a first energy yield rating label this summer.

 The ‘Next Generation Solution of Solar Renewables and Energy Storage’ conference was a side event at Intersolar Europe 2018. It was organized by the Global Solar Council (GSC), Asia PV Industry Association (APVIA), New Energy Industry Association for Asia and the Pacific (NEIAAP), Shanghai New Energy Industry Association (SNEIA) and co-organized by LONGi Solar.