A German-American research group has proposed a new model for treating photovoltaic installations as permanent assets, with maintenance carried out at regular intervals. With the new metric, he found it more convenient to run a module with 0.5% annual degradation for 35 years and a module with 0.2% degradation for 50 years.
A group of researchers from Forschungszentrum Jülich in Germany and the US manufacturer of thin-film solar modules First Solar have developed a economy model operate a photovoltaic installation as a permanent asset with maintenance being carried out at regular intervals.
The model was presented in the document The value of stability in photovoltaics, which was recently published in Joule, where the research group pointed out that the renewable energy industry is currently considering a lifespan of 25 years as the benchmark for the operation of solar power plants, noting that this parameter is strictly related to the performance guarantees set by the manufacturers and the political decisions that have supported these claims.
“I wouldn’t say solar module stability is more important than efficiency, because you need both, ”corresponding research author Ian Marius Peters said. pv magazine. “In research, however, I see a much stronger emphasis on effectiveness and, right now, journals are also asking [the] proven stability of these cells, but I still do not see the demonstrated record stabilities in the same way. According to him, the focus today only on the effectiveness of the panels should raise concerns in the industry, because the importance of stability for the commercial success of a solar product is not yet fully appreciated, in particular the implications for the durability of the devices.
Scientists cited the US solar company SunPower as a supplier that currently offers a 40-year performance guarantee for some of its products, based on low degradation rates which make them capable of reaching more than 70% of the initial yield after four decades. “A PV system owner has no reason to remove a PV system while it is operating safely and generating a profit,” the scientists said. “From this point of view, there is no reason why a PV plant should be taken out at all. “
Three economic models were initially considered by the research team: the updated cost of energy (LCOE), which balances the efficiency and cost of a photovoltaic system over its lifetime; discounted cash flow analysis, which estimates the value of an investment based on its expected future cash flows; and the steady-state model, which considers an energy asset to be in use indefinitely and includes all income and expenditure. “The change in mindset that continuous operation requires is a shift from focusing on recouping an initial investment to maximizing profits by dealing with degrading components,” the researchers said, referring to the report. third approach.
The compromise between degradation rate and efficiency was analyzed by ttechno-economic calculations in a large-scale photovoltaic project located in Arizona and a rooftop installation in Germany in which all modules are replaced with more efficient panels, a move which, due to the increase in capacity, requires an increase in the number inverters and cables. “Given these effects, we numerically adjust the efficiency until the economic performance is the same as that of the initial installation,” the academics said. “The results depend on the choice of system cost parameters but are independent of the specific performance. “
The American-German team discovered that the LCOE approach is the most sensitive to trade-offs between degradationutilization rate and efficiency, while the cash flow and steady state models were found to be slightly less sensitive. These two methods, on the other hand, treated power maintenance in the same way. “In the spirit of the transition to a long-term perspective, power maintenance is no longer seen as a single event but as a repetitive event with a fixed maintenance period,” he explained in Further, noting that the steady-state model allows, in principle, that more money can be spent on maintenance of electricity compared to the other two approaches. “In steady-state thinking, there is no particular optimum maintenance time, as there is when the system life is fixed.”
With the proposed mindset, maintaining the energy of a solar installation should be implemented whenever damage or technical issues arise. In order to help owners of PV assets decide when to perform maintenance activities, scientists have introduced the concept of the minimum economically useful lifee (MEL), which defines when replacing solar panels becomes more cost effective than not replacing them, specifying that higher degradation rates reduce MEL values and higher discount rates increase value. “The price cuts for photovoltaic modules reduce the MEL,” they added. “If the modules become cheaper, replacing the old modules becomes economically attractive sooner. “
The academics assumed learning rate for solar module prices of only 2.5% for the next three decades and found that the ideal lifespan of a photovoltaic asset could increase to 35 years by 2050. “By estimating the lifespan economically ideal, we find that a module with an annual degradation of 0.5% should work for 35 years and a module with 0.2% degradation for 50 years.
Importantly, one of the authors of the article is a researcher who works for First Solar, which announced in April that its cadmium telluride thin-film modules have reached what the company claims to be the rate of. lowest modulus degradation in the industry. “Achieving the SunShot target of 0.2% annual degradation further increases the ideal lifespan to 50 years,” the scientists said, referring to the target set for the degradation efficiency of solar modules by the US government as part of the Sunshot initiative.
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