In the past the value proposition of solar modules has been primarily about the lowest price ($/Watt) via the lowest manufacturing costs of conventional multi-Si modules. In the last few years, PV system cost has decreased significantly. In the meantime, PV module costs had dropped at a faster pace than Balance of System (BOS) costs, resulting in PV modules accounting for a smaller and smaller percentage of overall PV system costs.
PV industry will continue driving down module cost, but its impact on overall system cost reduction has become smaller and smaller. High efficiency mono-PERC modules not only help to reduce module cost, but also leverage to reduce BOS cost.
In basic terms, higher efficiency modules mean fewer modules are required for a given system power output leading to less electrical and mechanical hardware required, as well as savings on land and labour.
Cost savings using high-efficiency mono-Si PERC modules on commercial and residential projects, can be more significant than on utility-scale projects. The chart below highlights those potential savings on a cost per-watt (US$/W) basis.
Better Energy Yield with Mono-PERC Modules
LONGi Solar was a winner in the recent TÜV Rheinland “All Quality Matters” awards, having modules undergo energy yield simulation at different environmental conditions: Cologne (Germany), Datong (China), Kumamoto (Japan), Chennai (India) and Los Angeles (USA).
Using randomly selected module samples from production, TUV Rheinland established a module PAN file with performance measurement under different irradiance, temperature and incident angle conditions. LONGi Solar’s 60-cell monocrystalline PERC module (Hi-MO1) became the winner of the “PV module energy yield simulation (Mono group)”, the only award for monocrystalline products.
Real-world tests by China Electric Institute, which included two sites with very tough environments for PV modules, compared the energy yield of the Hi-MO1 modules to multi-Si modules from a Tier 1 supplier.
A small test plant (8 x 290W Hi-MO1 modules and 260W multi-Si modules, 3kW inverter) in Sanya, China, which is in the south of the country and experiences hot and humid conditions, demonstrated an average power generation that was 3.77% higher with Hi-MO1 modules compared to the multi-Si modules.
The other test site was in Tulufan in Northwest China, which experiences hot and dry environmental conditions. There, the Hi-MO1 modules produced on average a 3.64% increase in power generation when compared to the multi-Si modules.
Contributing factors to the superior performance of the mono PERC modules include better performance at low irradiance, slightly lower operation temperature and lower temperature coefficient, as well as improved voltage staying within the inverter MPPT (Maximum Power Point Tracking) range longer, enabling longer inverter operating time.
Slower Power Degradation
Extensive testing by the US National Renewable Energy Laboratory (NREL) has shown that mono-Si modules demonstrate lower long-term degradation rates than multi-Si modules, resulting in more electricity being generated over the long-term by mono-Si modules with the same power rating (Pmax) than by multi-Si modules.
In conclusion, the value proposition of using high-efficiency mono-Si PERC modules are:
• Higher efficiency/power density results in BOS cost savings (lower system cost.
• Mono-PERC modules demonstrate higher energy yield.
• Mono-PERC modules show a slower long term degradation rate.
It is clear that lower LCOE can be realized by using mono-PERC modules.
At Solar Power International 2017 trade show in Las Vegas, LONGi Solar introduced its 300W+ solar module series, with 60-cell modules delivering over 300W nominal power and 72-cell modules exceeding 360W.
This effectively marks the entry into the PV 3.0 era, which is based on solar modules with nominal power ratings above 300W becoming available in HVM (High Volume Manufacturing production. LONGi, can be seen as a pioneer in producing high efficiency, high quality solar cells and modules like mono-Si PERC, which is reaching multi GW-scale production levels.