Estimating the Learning Curve of Solar PV Balance-of-Systems for Over 20 Countries

About the Project
Although the costs of solar modules have fallen precipitously and have, thus far, followed an 80% learning curve, balance-of-system (BOS) costs have not declined at the same rate. Today, the BOS represents the majority of the capital costs for solar installations. The growing share of BOS in the total cost of solar systems has direct implications on its competitiveness.
For the first time, and with the aid of an extensive dataset, learning curves of the BOS component for residential systems have been deduced for over 20 countries. In addition to computing a global average for BOS learning at 89%, this modeling exercise showed that there are a number of cost reduction opportunities that exist in the BOS segment, and these require no (or little) financial policy support.
Key Points
The capital cost of a solar photovoltaic (PV) system comprises the module and balance-of-systems (BOS). The latter refers to everything else that is needed to make the solar system functional including cables, mounts, labor, etc. While modules are priced internationally, the BOS is countryspecific. Price developments of modules, which have been thoroughly studied in literature, followed an 80 percent learning
The LC for BOS in residential PV systems is estimated for more than 20 countries via an extensive dataset. We show that the BOS LCs for these countries are typically lower than that of modules, affirming the few single-country studies reported previously.
Our calculations yielded a global LC for the BOS of 89 percent, which corresponds to a progress ratio of 11 percent compared with 20 percent for modules.
The data was then divided into two periods – pre- and post-2008 – to study the effects of the global financial crisis on LC development. It was found that many countries were able to sustain progress in the LC post-2008 despite reduced financial policy support, indicating that there are effective steps that could be taken by policymakers to reduce BOS costs without requiring (significant) financial policy support.

项目概述
尽管太阳能组件成本已大幅下降，且迄今为止遵循80%学习曲线，但系统平衡成本（balance-of-system, BOS）的下降速度却并未与之持平。当前，BOS成本已占太阳能发电装置总投资成本的大部分份额。BOS在太阳能系统总成本中占比的不断提升，对其市场竞争力有着直接影响。

本研究首次借助大规模数据集，针对20余个国家的户用光伏系统BOS组件学习曲线进行了推导。本次建模不仅计算得出全球BOS学习曲线的平均水平为89%，还揭示了BOS领域存在多项无需（或仅需极少）财政政策支持的成本削减路径。

核心要点
太阳能光伏（photovoltaic, PV）系统的投资成本由组件与系统平衡成本（BOS）两部分构成。后者指保障光伏系统正常运行所需的其余所有成本，包括线缆、支架、人工等。尽管组件价格为全球统一定价，但BOS成本具有国别特异性。光伏组件的价格走势已在现有文献中得到充分研究，其遵循80%学习曲线。
本研究通过大规模数据集，对20余个国家的户用光伏系统BOS学习曲线进行了估算。结果显示，这些国家的BOS学习曲线普遍低于组件的学习曲线，这与此前仅有的少量单国别研究结论一致。
本次测算得出全球BOS学习曲线的平均水平为89%，对应的进步率为11%，而光伏组件的进步率则为20%。
随后，本研究将数据集划分为2008年前后两个时段，以探究全球金融危机对学习曲线发展的影响。结果发现，尽管2008年后财政政策支持有所缩减，但诸多国家仍能维持BOS学习曲线的进步态势，这表明政策制定者可采取有效措施在无需（大额）财政政策支持的前提下降低BOS成本。