© Annelie Bortolotti

You’ve just had shiny new photovoltaic modules installed on your rooftop, and they’ve started piping electricity into your home. That’s all there is to it, right? Maybe not. David Moser tells us how the Solar Bankability project crunched the data on the potential risks of PV plants to demonstrate how to improve their performance over their lifetimes.

Solar energy seems now like it is the “next big thing”, after it was heralded as the “next big thing” back in the 1990s. What took it so long?
 Moser: We needed to have a few things going at the same time to get to this point: first, policies that promoted renewables at the country and EU level, like the 2020 targets, for example. Secondly, we needed economic incentives to encourage industry and homeowners to install PV plants. And thirdly, we needed to reduce the cost of the plants themselves. There is a rule in the industry that when you double the worldwide cumulated module production, you decrease its cost by around 25%. As the technology has improved, we’ve seen massive cost reductions over the lifetime of PV plants.

What is their lifetime?
Moser: The standard response is 20 years, but this is a very artificial number because the business model was based on initial economic incentives that lasted for a limit of 20 years. There are some plants which have been in operation for more than 30 years.

These economic incentives dried up in Italy in 2013. When a homeowner installs a PV plant now, one of their first questions might be: “Will I ever make my initial investment back?”
Moser: The short answer is ‘yes’. With large PV plants, the return on investment depends on the framework of how the electricity is valorised, and this is more complex. The private homeowner will see reduced electricity bills rather than actual income. It’s now possible to produce energy at a lower cost over the lifetime of a PV plant than what you would spend in the same period getting your energy from the grid, and this is a fact anywhere in Europe.

As manager of the Solar Bankability Project for Eurac Research, your team was trying to quantify the risks that impede the return on investment. What did you find?
Moser: There are many potential technical failures for PV plants: incorrect installation, glass breakage, hotspots caused by cells working at higher temperatures, soiling of the panels from dust and pollution, ‘snail tracks’ which are an indication of the presence of cell cracks, rodents that eat through the electrical cables, and so forth. We tried to quantify the economic impact of these potential failures and then propose strategies to help the different actors in solar energy provision make informed investment decisions.

Can this help the average homeowner who wants to install solar panels?
Moser: These same technical risks can be there for smaller systems, but they are generally not detected until it is too late.

Why is that?
Moser: Large PV plants typically (but surprisingly, not always!) have built-in monitoring systems and maintenance packages that would be too expensive to include in smaller PV plants. The challenge is that unless there is constant monitoring of what is happening with a PV plant, the problems are unlikely to be detected in time, and this can have a negative impact on cost-efficiency over the lifecycle of the plant.

What can we do to avoid them?
Moser: We propose effective preventive measures: for instance: make sure you have certified or qualified installers, and for small PV plants, get proposals from two or three installers to compare their designs. There are also cheaper basic monitoring systems on the market for residential plants. We are not suggesting that residential owners can create a risk-free set up because that would cost too much, but at least they should have a certain regard for quality components and installers. What can seem like an added cost in the moment can save you money in the future. It’s like insurance—it might seem like a waste of money at first, but you’re sure happy you have it when something goes wrong.

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