Solar array maintenance: why are costs falling?
Solar array maintenance costs are at their lowest point yet, making large-scale solar projects more economically competitive than ever – but what is solar array maintenance and why are costs declining?
It has often been thought that solar is maintenance free, but this is not strictly the case.
Maintaining solar photovoltaic (PV) operations may typically be considered simpler and cheaper than competing energy sources, such as wind power and natural gas; however, the relatively small profit margins associated with solar makes it necessary to keep operations and maintenance (O&M) costs to a minimum to keep projects commercially viable.
Projected low O&M costs reduce financial risk and therefore increase the much sought-after investor appetite.
Over the last decade, the cost of solar power has rapidly fallen in-line with the demand for the carbon neutral, renewable energy source. Efficiencies of solar cells in producing electricity have also increased from 1%-2% up to an average 15% today.
As more projects are becoming financially viable due to lower expenses, it is only natural that O&M expenditure should fall too.
Costs halved in a decade
Based on a compilation of published reports, Andy Walker from the US-based National Renewable Energy Laboratory (NREL) estimates that, for old solar PV systems, O&M was on average $20 per kW a year, whereas now it is closer to $7.50 per kW a year.
"I think O&M costs are about half of what they were ten years ago," he says.
Christoph Reiners, head of solar at solar services company BayWa r.e which operates in Europe, agrees that O&M costs have 'more or less reached their lowest point'.
This is due to a number of reasons, such as improved reliability of inverters - one of the main electrical components in solar PV that changes the electricity created from DC to AC. According to a report by the Desert Research Institute, inverter breakdown is one of the most common causes for solar PV system performance loss.
"It is clear that inverters have become more reliable with lower O&M requirements and fewer failures," says Walker.
Many companies now also offer ten-year-plus warranties for inverters reducing the cost burden for owners.
Throughout the life of a PV system there are multiple issues that can lead to panel failure or loss of optimal efficiency, including panel cracking, decolourisation, and extreme weather and panel soiling.
At the new 53MW Broken Hill solar plant project in New South Wales, Australia, AGL, the company that delivered the project in January, installed 677,760 solar PV modules that self-clean from rain over an area of approximately 140ha.
Panel cleaning is essential to ensuring optimal energy output.
Adam Mackett, project manager for solar at AGL says the self-cleaning panels help with maintenance in dry, dusty locations, such as Broken Hill.
Broken Hill and the 102MW Nyngan solar plant project, also in NSW and delivered by AGL last June, has given rise to the large-scale solar industry in Australia.
Getting rid of inefficient and poor solar PV systems has also helped reduce O&M prices.
Walker says that some module types, such as flexible amorphous silicon, have shown significant failures and have skewed historic data to the high side.
"Those products are no longer available so that partly explains why costs are coming down," he adds.
People management and logistics handling
Better data management and new tools for the task have also helped reduce the maintenance costs of solar arrays.
"Profound remote data analysis has reduced the need for on-site personnel and measurement systems," says Reiners.
A plant of 40MW or over can justify one person being involved on a project full-time, according to Reiners, with this person requiring occasional support from additional technicians.
The daily routine for solar power maintenance typically involves visual inspections and torque tests. By using remote data analysis system issues can be better predicted and mitigated, for more effective management of people and resources.
Improving logistics for those working on-site by having key maintenance and repairs components available at a spare parts depot on-site or nearby, and having technicians situated close to a site can also reduce solar panel downtime, says Reiners.
"Matching availability and performance ratio guarantees can only realistically be achieved by reduced travel times to guarantee swift interaction times," he says.
"Our technicians take full ownership and responsibility for the projects that they manage, this provides a proactive approach to maintaining their plant."
Another way O&M costs are being reduced and operations streamlined is by engaging those responsible for maintenance in the initial stages of the project.
At Broken Hill solar plant, AGL involved maintenance workers early on.
"The employees maintaining the plant were involved during the construction and are very familiar with the equipment and site which has aided the transition into operations," says Mackett.
"Maintenance of the second largest solar plant in Australia will involve proactive management of all the electrical connections and equipment," he adds.
AGL will be responsible for the operation and maintenance of Broken Hill for its 30-year life and has engaged First Solar, the EPC contractor, for the plant's upkeep for the first five years.
Four full-time employees will manage O&M at Nyngan and two at Broken Hill over their 30-year lifespans.
Just as the solar industry is evolving so are best practises, particularly in the US. NREL provides an annual best practise guideline, co-authored by Walker, and the reduction of soft O&M costs has been the subject of projects by the US Department of Energy's National Nuclear Security Administration (NNSA) initiative, the Sandia National Laboratories, and other US organisations.
However, solar PV O&M challenges still remain, one being the low availability of skilled workers in Europe, due to massive installation rates in recent years. Reiners explains that, "Qualified experts are hard to find."
Walker also warns that efforts to improve PV modules by using thinner glass and cells may increase O&M expenditure in the long-term, as the units may be more susceptible to breakages, although, he says, "the evidence is not in yet".
Solar PV O&M costs are expected to fall further, but Reiners believes this is not necessarily a good thing and could negatively affect maintenance providers.
"Further cost reductions will influence negatively on the maintenance quality and will impact on the production yield," he says.
"We have witnessed price falls recently in Germany and Spain where investors heavily cut the operating costs in the last years."
However, as the industry has shown in the last decade through continually reducing its costs and improving efficiency -both for production and O&M - it is not engineering obstacles and high costs that hamper the solar industry but financing uncertainties, a lack of access to subsidies and private financing.