The changing economics of solar power generation are generating cost pressures within the photovoltaic (PV) sector, and while it began with robust specifications, these have been trimmed as competition has increased.
“Although the steelwork supporting solar panels comprises a relatively small fraction of the overall investment, it is the foundation of solar plant success - and the selection and quality of steel and corrosion control have not received sufficient attention,” warns Executive Director of the Hot Dip Galvanisers Association of Southern Africa (HDGASA), Robin Clarke.
Where sun meets steel
Having encountered multiple instances where a ‘cut and paste’ of the generic specifications (applied when the industry launched in South Africa some 10 years ago) does not apply to the environments in which some solar plants operate today, Clarke says that the HDGASA is working alongside various photovoltaic industry installers to improve quality standards through the correct specification of support structure materials.
“Corrosion protection ensures that structures achieve service life expectations and meet baseline return-on-investment calculations. The steel structure should remain serviceable after 10 or 20 years to house the next planned electrical upgrades. It should outlive the electrical plant, so that upgrades can be done without disturbing what has already been mounted or planted. On this basis, hot dip galvanised technology is an excellent choice, since corrosion control in most environments can exceed 40 years.”
However, specifications must be carefully considered: “Mount systems for ground installation were originally thicker steel. However, once the sectional thickness was trimmed down, hot-dip galvanised coating pick-ups decreased. This sufficed when systems were installed in fairly benign soil and atmospheric conditions - but not in more hostile environments,” Clarke continues.
“The HDGASA has repeatedly appealed to project owners to perform baseline environmental and geological soil assessments, checking designs for appropriate material specifications. We engage with many suppliers, designers and engineers who recognise this - but pressure remains, driven by cost considerations - to select less-than-optimal materials,” he notes.
Another challenge has emerged with the growing popularity of rooftop solar systems amongst commercial and residential property owners. Initially, installations were carried out with seemingly scant regard for the condition of the roof sheeting. Nowadays, roof sheet assessments ensure that installations are not fitted to roofs that require extensive maintenance or replacement within the time frame required for the solar plant to deliver a return on investment.
Shining a light on localisation
Clarke says the HDGASA is disappointed that solar plant steelworks are still imported when capacity exists in South Africa: “We encountered one plant where material imported from Europe was at variance with the specification required for the installation, had suffered damage during storage and should not have been installed. However, the ability to hold a company accountable that is 15,000 km away is absolutely zero. We had the same problem with components from the Far East, which were utilised in a coastal application.
In South Africa, we have capacity, quality and accountability on our doorstep. This would circumvent some of the problems we encounter in the field.”
Clarke believes that many companies in the solar sector wish to operate sound, sustainable businesses and have benefited from HDGASA training and advice; however, they face challenges from other solar operators that undercut on price, either by compromising on standards or by lacking knowledge of appropriate specifications.
Solar-powered solutions
“This is a growth curve. Companies competing solely on one-off capital investment figures have little incentive to present robust specifications as an alternative. We are working with suppliers to ensure customers get real value for money,” Clarke explains, adding that there is a greater need for accountability across the entire steel supply chain as demand and volumes grow.
He cautions that in a diverse environment such as South Africa, a single standard will never apply to all: “Design criteria must be specific to where a plant is built. There has been a lack of understanding of regional requirements. We are encouraging project owners and designers to consult corrosion control experts, who can provide accurate information on the corrosivity of the soil and the overall environment,” Clarke concludes.