Electricity + Control November 2019

ENERGY MANAGEMENT + ENVIRONMENTAL ENGINEERING

at Energy Partners, points to some of the important factors to be considered before entering into power purchase agreements of any nature. Insist on a savings guarantee To start, van Eetveldt says that every PPA should be based on a predetermined performance agreement. “The agreement should state explicitly how much the service provider’s rate for electricity will be and provide a guarantee that these rates will always be meaningfully less than the tariff of the grid alternative.” The installation at the Longmeadow Distribution Centre was commissioned as part of Pick n Pay’s fifteen-year campaign to halve its electricity consumption by 2025.The PV system is designed to reduce the retailer’s total grid usage by a significant 6%, and the savings guarantee ensures that the service provider reaches this production target. In addition, the client needs to ensure that the PPA contract guarantees annual energy production targets. If production targets are not met for any reason, the client should be able to claim penalties from the service provider. Ensure a strong track record According to van Eetveldt, the track record of the service provider should also be an important deciding factor when entering into a PPA. “PPAs are typically long-term agreements and it is important to partner with service providers who will be there in the long run in this fast-changing industry. This means choosing a partner that has adequate financial backing, and has already built up a reputation as a reliable service provider.” Another aspect where a strong track record is advantageous is in the drafting of contracts with new clients. “Contracts need to be updated regularly to ensure that they are watertight for all parties involved and you need a service provider who

has enough industry experience to understand that a one-size-fits-all approach does not apply to PPA contracts. Each business has unique requirements, which need to be worked into a contract.” On the Longmeadow project, for example, Energy Partners Solar had to ensure that transparent buy-out values were written into the contract. This affords Pick n Pay the option to exit the PPA at any time, if the need arises. Operation andmaintenance efficiency is key Any investment in solar power is a long-term (25 years and more) commitment. Solar power generation in the South African corporate and industrial market has grown rapidly over the past five years and currently exceeds 700 MW of embedded generation capacity. “As many of these system owners have come to realise, the efficient operation and maintenance (O&M) of these assets is crucial and best handled by specialised O&M teams,” says Dewaal van Heerden, Head of O&M at Energy Partners Solar, who will soon be monitoring and maintaining more than 50 MW of rooftop and ground-mount solar systems across Africa. He points out that, “If the performance of a PV system decreases by as little as 12%, beyond the expected panel degradation, the losses to cost-savings will exceed the price of the entire system over its lifetime. Dirt and pollution can hypothetically reduce system performance by up to 40%, while micro cracks, potential-induced degradation losses and physical damage can cut performance by a further 32%.” The most important driver of savings on a PV system (apart from the avoided grid supply cost) is the actual solar yield that can be achieved. The O&M team’s task is to ensure that this number is always as close as possible to the yield for which the system was modelled. When judging solar yield a number of aspects should be considered: - The original yield estimation without any soiling losses - The allowance for soiling (especially difficult to estimate on rooftop systems) - The weather patterns for the period under review - The effect of factors outside the solar provider’s control (load shedding or client shut-downs). Van Heerden notes that since commissioning, the Longmeadow system has achieved the exact modelled yield (actual weather patterns delivered

The efficient operation and maintenance of embedded power generation assets is crucial and best handled by specialised O&M teams.

28 Electricity + Control

NOVEMBER 2019