Owners of older renewable energy installations need to ensure that any system repairs or replacement parts do not jeopardise their eligibility for support payments.
It is 10 years since the first projects were accredited under the government’s Feed-in Tariff (FiT) scheme.
As systems age, the likelihood of technological faults due to manufacturing defects, sub-standard installation, poor maintenance, accidental damage or wear and tear, is likely to increase.
While FiT rules require systems to be kept in good working order, there is little provision allowing for major component failures or advances in efficiency.
Therefore, owners need to be careful when arranging repairs, says Gary Haines of solar adviser and installer NWT Energy.
“The main point to remember is that any repair or replacement part must not increase the total installed capacity of the system, otherwise FiT eligibility could be at risk.”
In the case of rooftop solar for example, the latest monocrystalline modules (black-coloured panels) offer greater efficiency than the old-style polycrystalline (dark blue) units. This must be considered if replacing old faulty panels, he says.
New modules typically generate up to 300-330 Watts, compared with 185-250 Watts for a comparable older version.
“If you’re fitting a higher wattage replacement panel, it may be necessary to remove other panels to ensure the system stays within the FiT generation limit.”
While major manufacturers have moved on to new technology, it is still possible to buy older polycrystalline modules. However, matching equipment exactly can be tricky, he says.
“A lot are similar in size, but dimensions can vary, notably depth, which could cause subsequent issues with clamps and mounting frames.”
Need for change
Jon Swain of the Farm Energy Centre says FiT regulations must change to give more flexibility for repairs or replacements in older systems without jeopardising eligibility.
Similar changes have already been made to the Renewable Heat Incentive (RHI), which means failed equipment (for example, a broken biomass boiler or blown CHP engine) can be replaced where necessary, with RHI support paid only for the lesser of the original capacity registered or the capacity of the replacement.
“This issue is only going to get worse as systems get older and more require larger repairs or investments.
“We would like BEIS [Department for Business, Energy and Industrial Strategy] and Ofgem to bring FiT legislation more into line with the RHI replacement regulations in this regard,” says Mr Swain.
Provision must also be made for complete system loss, such as in a fire, because current rules do not allow an FiT claimant to install a replacement system and continue claiming under the original scheme.
Ofgem is looking into the issue with BEIS, and advises any FiT claimants to ensure repairs or replacements keep installations within the appropriate generation capacity limit.
Solar repair solutions
Solar panel faults are comparatively rare and many issues are linked to installation, says Mr Haines, who cites figures from a leading manufacturer, which show just 40-50 of every one million solar panels produced by the firm over the past eight years developed a fault.
Faults often occur outside the main warranty period, but if panels are still under warranty, it may be possible to claim through this, although many installers and manufacturers are no longer in business, and even where they are, it can be difficult to make a claim, he says.
Causes of faults:
• Poor panel manufacturing quality
• Inverter failure
• Sub-standard installation of panels or electrical components
• Impact damage (for example, birds dropping stones, falling branches, hail, machinery accidents)
• Poor maintenance (lack of regular cleaning, especially in dusty environments or on shallow-pitch roofs).
Mr Haines outlines three options available to those needing to replace a faulty solar panel.
1. Source old-style modules
• Cheapest option (panels typically £200 each)
• Likely to get close match to original equipment
• Supply becoming more limited as technology advances, so prices increasing
• Old technology, less efficient
• Example cost for replacing two rooftop panels in a 50 kWp system: £700-900 (includes equipment, technicians, access, etc).
2. Remove failed panels entirely
• No need to find suitable replacement panels, but…
• Reduces overall generation capacity
• Electrical rewiring may be needed to balance power flow through inverters (each ‘string’ of modules feeding into an inverter must contain the same number of panels). This may raise other issues, such as if clamps are difficult to remove and other parts are needed
• Example cost: around £1,000
3. Replace string inverters with optimised inverters
• Optimised inverters balance the system’s power output, allowing different wattage modules to be fitted in the same system
• Helps mitigate shading effects
• Fire safety benefits and longer warranty
• Improves overall efficiency
• Significantly more expensive – optimisers must be fitted behind every panel or every other panel
• Example cost: £20,000-25,000 (based on a 50kW installation)