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PV replacement calculator

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This work (other than the webtool) has been published in this RIVM brochure

Calculation method background

We have used calculation methods from Rajagopalan et al (2021), and combined this with the data provided by the IEA factsheet using the updated data from the IEA PVPS life cycle inventory. We perform the analysis on a mono-Si PV system, since it is expected this technology will dominate the market in the short term future, and environmental data availability is much higher compared to other technologies.

In the IEA factsheet, for span of 30 years, the total carbon emissions per generated kWh for a mono-Si PV system are 42.5 g CO2-eq, with the following scope and conditions:

Equation 1. Taken from Rajagopalan et al (2021)

Rajagopalan et al (2021) provides an equation to calculate the yield for a PV system over a span of 30 years, including the effect of replacing panels before its expected lifetime (equation 1). With this equation, we calculate the 30 year yield of the PV system described earlier: 78536 kWh. Together with the carbon coefficient, we find that this system takes (42.5 g CO2-eq /kwh * 78536 kWh = ) 3337 kg CO2-eq per panel (to produce, maintain, and discard the panel by recycling).

For the same system, we can calculate the carbon coefficient for an installation in the Netherlands. The irradiation in the Netherlands is around 1044 kWh/kWp, so this results in a baseline of 39.7 g CO2-eq/kWh. This result fall within the range of carbon coefficients calculated by TNO, being 29 g CO2-eq/kWh and 55 g CO2-eq/kWh for a system produced with a European and Chinese energy mix profile, respectively. This system and its performance forms the baseline for this study.

Equation 2. Taken from Rajagopalan et al (2021)

With the given baseline, we can assess various replacement scenarios based on the equation 1 in combination with the equation 2. In replacement scenarios, where the system will be replaced with newer panels before its expected lifetime, it is necessary to take into account future technological development (especially for the rapidly evolving PV technologies). Newer panels are usually more efficient, and can have a lower carbon profile over its life cycle due to efficiencies in production or higher circularity (e.g. higher material recycling or higher modularity). Equation 1 includes a, the yearly projected power rate improvement (in %), which is expected to be around 1.4%. Equation 2 includes b, the 5-yearly projected environmental improvement rate (in %), which is expected to be around 5% every 5 years. With equation 2 we calculate the total carbon footprint associated with the used PV system over 30 years. With equation 1 we calculate the total electricity generated over 30 years. We compare the performance by the functional unit g CO2-eq/kWh, so; dividing the result of the total carbon footprint with the total electricity yield.