## 1 Introduction  
One of the most significant challenges for humanity is the need to shift away from using fossil fuel technologies for electricity generation and transportation needs with a transition towards the use of renewable resources. Without additional efforts to reduce greenhouse gas emissions beyond those already in place today, the projected emissions growth, driven by continued population and economic growth, is expected to result in an average increase of an alarming 3.7-4.8 \({}^{\circ}\)C by 2100, compared to pre-industrial levels [1]. Such increases in atmospheric CO\({}_{2}\) levels could lead to dramatic changes in the thermohaline circulation patterns that regulate the world's climate, with severe consequences for marine and terrestrial ecosystems [2]. As a result, significant cuts to anthropogenic greenhouse gas emissions are required by 2050 to avoid these dramatic changes. One promising approach to reduce greenhouse gas emissions is through the widespread adoption of photovoltaics (PV) for electricity generation. The PV industry is rapidly growing, with astonishing growth rates of 30-50% per annum since the 1990's [3; 4], alongside significant reductions in cost [5]. In 2016,approximately 75 GW peak (GWp) of PV power was installed, taking the cumulative installed PV capacity to \(>\)300 GWp [5]. One of the primary drivers for the increased uptake of PV is through the cost reductions achieved by improving the efficiency of the PV modules. However, approximately 95% of PV modules are fabricated using p-type silicon substrates [5], which are prone to degradation when exposed to sunlight [6; 7], even at temperatures as low as 70 \({}^{\circ}\)C encountered under typical working conditions of solar panels. In p-type Czochralski (Cz) grown silicon, such light-induced degradation (LID) has plagued the industry for decades and has been a driver for intense research into alternative silicon materials for PV production. This degradation is believed to be due to the formation of boron-oxygen (B-O) related defects [8], although the actual composition of the defect is still unclear and remains a contentious issue [9; 10; 11]. A thorough review of B-O defects by [PERSON] et al. can be found in [12]. B-O related degradation can reduce the 1-sun standard test conditions (STC) efficiency of silicon solar cells by up to 10% relative to the performance immediately after cell production [13]. However, in practice it is much smaller than this, typically plateauing at a value of 3-4%relative for conventional aluminium back-surface-field (Al-BSF) solar cells [14] and 4-6%relative for the passivated emitter, rear cell (PERC) structure [15]. Furthermore, this performance change is transient with an initial degradation cycle followed by a natural recovery back to the starting performance. The net impact on the total energy yield of an affected module depends on many factors and can last days, weeks, months or even years depending on the installation location and type [16]. This performance instability has created uncertainty in the minds of large-scale installers who from a bankability perspective prefer the issue be mitigated during manufacturing. With a prediction of 100 GW of global PV module sales in 2017 [17], B-O related degradation of p-type Cz solar cells could cost solar cell manufacturers $390 M for the year. This valuation is based on a 2016 market share of 20.5% (4.4%) for p-type Cz Al-BSF (PERC) modules [18] with a degradation of 4%relative (6%relative) and selling price of US 0.35 $/W (0.40 $/W) (12 December 2017) [19]. Despite the uncertainties surrounding the nature of the defect, significant progress has been made over the last ten years for the elimination of B-O related LID. This paper will review the progress in the understanding of B-O LID mitigation processes and the impact on the industry.