With the market now dominated by the competitive auction process, new solar PV projects need to seize every opportunity to reduce costs and improve performance. Developers are used to negotiating the best contractual and commercial terms, but many miss out on opportunities for technical optimisation. 

For one recent project, WSP ran over 500 scenarios to find the optimal techno-economic solution for our client. This led to a reduction in the bidding tariff of around 1.5% compared to the base design, which could be the difference between winning and losing a bid (in this case our client won the bid!).

Optimising energy performance through modelling

So how do you optimise the energy yield from a solar PV plant? The answer lies in technology selection and design optimisation in the face of often-conflicting factors such as capacity limits, bankability and long-term performance. And since the advent of bi-facial solar modules, it also involves accurately quantifying and maximising the additional energy this technology offers.

Until recently it’s been difficult to accurately simulate bi-facial PV performance. For example, the over-simplified methodology used by tools such as PVsyst can underestimate performance of bi-facial PV by as much as 5%. At WSP, we’ve developed more advanced modelling tools to overcome the drawbacks of off-the-shelf packages. 

Our approach significantly reduces the uncertainty of the bi-facial PV yield estimate, which improves the bankability of the overall project. We recently reduced the cost of a project in Sub-Saharan Africa by circa 4% by analysing multiple mounting structure options. 

This is an important question, given that construction accounts for the bulk of the cost of a solar farm. 

The simple answer is to avoid overbuilding but that is easier said than done. Understanding the minimum functional specifications, grid code requirements and the provisions of project agreements is key to achieving a competitive, yet compliant, solution. 

For a recent 300MW project, we found that, based on the project’s specific techno-economic parameters and available prices, oversizing the inverter’s capacity was a better solution for providing the required reactive power support, instead of using Static Var Generators (SVG). The solution improved the project’s levelized cost of energy (LCOE) by circa 2.3% while remaining compliant with the reactive power support requirements. 

Having a good understanding and a clear picture of the price reduction and efficiency improvement path from the equipment manufacturer is also key. This helps ensure the modelling is performed for the right year, when the new PV modules and inverters ranges will be available. 

Reducing operation and maintenance costs

While opex is not typically as critical as capex to the financial viability of a project, there are still significant opportunities to improve financial performance. 

Then there is the question of whether you should use a maintenance reserve account or an inverter warranty. Depending on the location and operational environment, full-wrap lifetime warranties may be cheaper and more effective. String inverters make operation and maintenance easier in locations with low-skill, low-cost, plug-and-play solutions especially in countries where the supply chain is its infancy.

Ultimately, an operation and maintenance methodology tailored to site-specific maintenance and cleaning requirements will minimise the cost of water and labour, robotic cleaning and other factors.

There are other options to consider too – such as using batteries to maximise returns or replenishing degraded capacity over the years. 

A comprehensive understanding of how these different technical optimisations might benefit your project could be the difference between success and failure.

To learn more about these, contact us for a copy of our Making Solar Work report – or get in touch with Ahmad or Luca.