LCOE of monofacial, bifacial solar modules


From pv magazine USA

Clean Energy Associates (CEA), in an attempt to answer one of its most commonly asked questions, has released a new case study that compares the levelized cost of energy (LCOE) of bifacial and mono PERC solar panels and outlines scenarios where each makes the most sense.

CEA said the crux of the issue is that bifacial modules promise an energy yield that is 6% to 10% greater than traditional mono PERC modules. But they also come with higher dollar-per-watt module costs, as well as higher expenses for balance of system (BOS) and installation. So when do the benefits outweigh the costs?

The answer can change depending on project location, size, and the other hardware used, especially trackers. Capturing bifacial’s value and its impact on a project’s bottom line over a 25-year to 30-year life cycle begins with the basic LCOE formula, (life-cycle cost of the project divided by lifetime energy production) but a litany of factors can change the values in both cost and production.

To make a base evaluation, CEA used PVsyst to model optimized layouts for the modules and locations they analyzed. After that, they priced all equipment, labor, design and engineering, permitting, overhead and margin, and other costs – except for the modules.

Their formula also inputs the estimated annual kilowatt-hours generated, the power purchase agreement (PPA) price, the investment tax credit, and operations and maintenance (O&M) costs. Variables in the equation include the longer life cycles of bifacial panels – 25 to 30 years – and their higher BOS and installation costs. For the sake of simplicity, degradation and O&M were set at about 0.5% per year.

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Once the full gauntlet of factors was accounted for, a “hurdle price” – a price below which a bifacial panel provides additional value, based on the LCOE of a sample single-face system – can be established. The hurdle price is then used to back-calculate the price-per-watt module value for one or more bifacial panels.

CEA prepared a hypothetical comparison between monofacial Module A, and two bifacials, Module B and Module C, for projects in Massachusetts and Mexico. For this hypothetical scenario, the goal was to see whether purchasing a large supply of one of the selected bifacial panels would make financial sense for the two locations.

Image: CEA

Even with the very large differences in production and base LCOE related to location, Bifacial Module C delivered higher and comparable module value.

To wrap up the case study, CEA said that the model still has room for improvement, as it does not yet incorporate comparisons for the increasingly popular large-format modules that have hit the market. Larger modules require wider row spacing, which in turn could mean longer wire lengths and a resulting voltage drop. An LCOE module comparison can reveal the positive or negative value of these trade-offs.

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