The global solar energy market continues to grow. Renewables are in greater demand than ever as the climate crisis takes hold and as governments increasingly provide incentives for renewable energy solutions. Total solar capacity worldwide reached the landmark milestone of one Terawatt (TW) capacity in April 2022. To put that growth into perspective, it took almost a decade for global solar capacity to reach 1 TW, from a combined capacity of just 100 GW in 2012. Yet it is predicted that solar capacity worldwide will more than double to 2.3 TW by 2025, i.e. in just three years.
There is significant money at stake: the value of the global solar energy market should reach $223.3 billion by 2026, equating to a compounded annual growth rate (CAGR) of 20.5% between 2019 and 2026. There is no doubting the continued expansion of new farms, with the fastest growth expected not in the usual ‘solar behemoths’ of China, India or Australia, but in the European Union (EU).
However, even with all these glowing growth projections, there are a number of challenges in setting up and operating solar farms. Not only is their installation expensive and logistically complex, but, once in operation, the inspection and maintenance of solar farms can be challenging due to a number of factors, ranging from the geographic to the demographic. This article will provide an overview of these challenges and how autonomous robot inspection is a viable and cost-effective solution for each of these issues.
The Imperative of Clean Solar Panels
There are a number of factors that can create challenges regarding inspections and maintenance of assets in solar farms. First and foremost, solar panels (which, for the purpose of this article, can include solar mirrors and heliostats) need to be as as spotlessly clean as possible if they are to maximise their power generation capacity. They cannot convert 100% energy from solar energy received if they are dirty or obstructed in any way. This is due to lower levels of irradiation, which is, along with higher temperatures, the leading method by which solar panels are able to efficiently convert light into energy.
It is also important to note the interconnectedness of solar panels in a farm. An under-performing panel will mean that an entire ‘string’ or chain of panels will be affected. The result is a solar farm not operating at maximum efficiency and output. It is therefore of paramount importance that every panel work to its maximum capacity. Not surprisingly, any physical or natural elements that can accumulate on solar panels are problematic, and can include everything from dust and mould, to bird droppings and ash from forest or grass fires. Popular Mechanics has cited studies that have estimated that output power generation from dirty solar panels can decrease by up to 25%.
The sheer scale of having to ensure that every solar panel is clean becomes apparent when one considers that 3,125 solar panels (at an average of 320 watts per panel) are required for just 1megawatt of power. That means a solar farm with 1 Gigawatt capacity will house approximately 3 million solar panels. That does put the maintenance and cleaning imperative into stark perspective!
The Autonomous Inspection Solution:
Robots can be used in a variety of ways to help combat solar panels becoming excessively dirty and, thus, impaired. Condition monitoring is one solution, by which robots fitted with infra-red sensors can monitor important factors that help assess the condition of panels such as voltage, current, temperature and humidity. Deviations in these readings can flag the potential of panels being dirty or otherwise impaired due to natural elements. Thermographic reports generated by robotic and drone inspections can be helpful. Wear and tear of panels due to time and environmental factors can also be monitored.
There are also a number of autonomous robots for cleaning already available in the market. The downside is that the majority of these are remote-controlled, and thus still require human labour (and time) in order to be operated. However, 2022 did see the arrival of autonomous robots capable of cleaning solar panels in all types of conditions, and drawing their power from an embedded PV panel and battery.
Factors That Impact Solar Farms
Water for the purpose of cleaning solar panels can be a significant factor in any solar farm, particularly depending on location. Water for cleaning purposes in arid regions such as southern Europe, India and Australia, can be especially high, with up to 24,000 litres of water needed to clean a small 1MW solar farm. Furthermore, the use of ‘hard water,’ such as that from boreholes or wells, can cause residue deposits to accumulate on glass panels, which will inhibit uptake of light energy.
Vegetation is another key environmental factor at many solar farms. These facilities are, due to their land requirements and being in the open air, invariably in remote locations surrounded by vegetation. This can cause maintenance headaches. Animal intrusions are a further risk at solar farms. Mice and other burrowing rodents and small mammals can cause expensive damage to panels and other equipment.
The Autonomous Inspection Solution:
Regular and reliable inspections of solar farm equipment will result in more timely recognition of the condition of solar panels. Water can thus be used sparingly and only when needed for the purpose of cleaning said panels. Importantly, cleaning of panels will only be required when actually needed, rather than at pre-scheduled times when cleaning may not be required or not opportune, either due to climatic or other factors.
There are grass-cutting robots on the market for the upkeep of surrounding vegetation, similar to those used to cut grass in French vineyards. They are certainly a far better option than the use of herbicides at a solar farm which causes soil erosion and eventually destabilises solar-panel mountings.
Human-Related Challenges For Solar Farms
As with any industrial facility, employees or contracted specialists are needed at solar farms in order to undertake much-needed maintenance work and inspections.
This need for labour at solar farms can be problematic for a few reasons:
Ø Safety: as previously noted, most solar farms are in remote locations. This means inspection and maintenance teams have to travel long distances to get to solar farms. Working in extreme cold or hot conditions can also affect the health of workers.
Ø Labour shortages: maintenance and inspections at solar farms requires skilled labour. However, the aftermath of the COVID-19 pandemic has witnessed a dramatic labour skills shortage worldwide, including in the maintenance and inspection fields.
Ø Demographics: many countries are experiencing severe shifts in their demographics, particularly in affluent societies, such as those in Europe, Japan and South Korea. The number of working-age people is shrinking due to the demographic shift. This puts further pressures on labour, with smaller pools of skilled people being able to do perform inspection and maintenance tasks.
The Autonomous Inspection Solution:
Autonomous inspection is the antidote to the labour-related factors listed above, including the ongoing skills crisis worldwide, not to mention the looming demographic crisis. Not only does autonomous inspection plug gaps in the workforce, it also relieves humans from dull, dangerous and repetitive roles. Thus, increasing work safety standards and freeing employees to perform more fulfilling work.
Securing Solar Farms
Security is another key risk factor at many solar farms. Being typically remote or in rural areas means that breaches are easier. Also, these farms can be quite large and sprawling in size and scale, with the largest farms being thousands of acres in size. Ensuring adequate surveillance equipment for such large areas can be expensive and almost impossible. Solar farm thefts are a real threat, with solar panels, inverters and cables having potentially high resale values on the black market.
The Autonomous Inspection Solution:
Unsurprisingly, autonomous robots, especially when coupled with drones, have an excellent role to play in security management at solar farms. Not only can they be used for the general, 24/7 surveillance of assets and perimeters, but they can also be used to detect unwanted intrusions by wildlife and people alike. Perhaps most importantly, the very same system of robots and drones acting in unison for security purposes can also be used for inspection purposes.
To conclude, the trend in solar energy is strongly upward, but so too are the threats to solar facilities, be they human or natural. It is for those reasons that autonomous robots can play a pivotal role in the maintenance and inspection of solar farms.
