According to IHS, research and development initiatives to increase the efficiency of crystalline photovoltaic modules were not a priority until recently because the module manufacturing industry was focused on increasing production to meet surging demand. Higher-efficiency cells could produce a panel price markup of 10% to 15%, and in an industry fixated on price, performance takes a backseat.

This has changed. With crystalline PV module prices stabilizing, the stage is set for manufacturers to begin competing on the basis of performance. Furthermore, project finance due diligence is taking a closer look at expected lifetime yields, which makes module output more important.

Paul Dailey, product and technical sales manager for AEE Solar, says “high efficiency” with regard to p-type monocrystalline modules describes products with conversion efficiencies over 17%. For n-type modules, area efficiency is typically in the 18% to 22% range.

“When the term ‘high efficiency’ is used as a class, it’s most often referring to n-type cells and modules, which are inherently more expensive and have different design standards,” Dailey says. “Of course, there are also multi-junction cells that can reach over 40% efficiencies in concentrators, but those aren’t really relevant to this kind of discussion - at least not yet.”

Dailey says virtually all projects can benefit from higher-efficiency modules; however, there are cost trade-offs that must be considered. The cost-per-watt premium on modules with greater efficiency must be offset by corresponding cost-per-watt reductions in balance-of-system (BOS) and labor costs. When systems have space constraints, high-­efficiency modules can help meet the energy production goals.

“Often, a 265 W to 275 W 60-cell, p-type module is a good compromise between maximizing system output in the available space and minimizing total costs,” he says. “New fire codes are starting to limit the proportion of a rooftop that can be covered with a PV array, so space constraints may be a more common project challenge in the future.”

In AEE Solar’s experience, the area efficiency of standard 60-cell, p-type modules has been increasing at a fairly steady pace over the last several years, gaining roughly 10 W each year. Dailey says several monocrystalline module manufacturers he has talked to expect their production curves to favor 280 W or more by the end of this year.

“That starts to touch the lower end of the n-type module efficiency range, but at a significant cost advantage compared to n-type manufacturing,” Dailey says.

Manufacturers are under constant pressure to increase their cell and module efficiency because it is regarded as the best way to increase margins. A 60-cell module costs about the same to produce whether it has an output of 250 W or 280 W, but prices are typically set in cost-per-watt terms.

“N-type and other high-efficiency cell and module manufacturers are no exception to this, so I think we’ll continue to see meaningful differentiation as long as these modules can demand a sufficient premium in the market,” Dailey says.

Because of the premium price tag on high-efficiency modules, developers usually have to have specific reasons to justify the added expense.

“There are certain circumstances when I will specify high-efficiency modules, such as when the cost of the land or the solar racking is expensive,” says Scott Schumacher, project developer for Borrego Solar Systems Inc. “However, my choice of efficiency will always be dictated by which module delivers the best solution for my customer.”

“One instance in which high efficiency would be more suitable is a space-constrained scenario, with a goal or requirement to meet a certain system size,” says Joe Harrison, senior project developer for Borrego. “Some rebate programs have required minimum system sizes in order to qualify, and sometimes the project is trying to achieve a certain size but simply doesn’t have the space to get there without using high-­efficiency modules.”

Another example is if the developer is faced with challenging site conditions that impose expensive BOS costs - such as a landfill or a brownfield - where the racking solution and the site work are unusually expensive. In that instance, Harrison says it could make sense to pay more for higher-efficiency modules in order to reduce the footprint of the array and save on the BOS costs.

In many cases, the customer’s main objective is to obtain the lowest levelized cost of electricity (LCOE) over the expected life of the array. Factors such as initial purchase price of the modules and the cost to maintain the system may be more for a high-efficiency module, therefore increasing the LCOE. Furthermore, many high-efficiency modules are not yet compatible with 1,000 V systems or microinverters.

“Module efficiency is one of many factors that must be considered when designing a solar project,” Schumacher says.

Reaching higher

In a white paper, Stephen Shea, chief engineering officer for Georgia-based PV developer Suniva argues that cost-per-watt is a poor measure of value. In contrast, LCOE is perhaps the most important measure of the actual value of a system, based on its true power output in its installed configuration and over its useful lifetime.

“Importantly, the units of LCOE are dollars per kilowatt hour ($/kWh), a unit of value to which everyone who pays an electric utility bill each month can relate,” Shea writes. “Rating a PV system in this way not only immediately allows intuitive comparisons between different PV technologies, but also allows direct comparisons with conventional sources of electricity.”

More research money is being made available to explore how high-efficiency silicon modules can contribute to improved LCOE.

In December, the U.S. Department of Energy (DOE) awarded Suniva and its research partner, the Georgia Institute of Technology, a $4.5 million grant to deploy a low-cost, high-efficiency silicon PV cell technology into the marketplace within three years. Suniva’s 200 MW cell and module facility in Norcross, Ga., is the site selected for this grant provided by the Solar Manufacturing Technology program.

According to NPD Solarbuzz, the share of high-efficiency p-type monocrystalline and n-type modules is set to decline from 29.6% in 2013 to 29.3% this year, and production will increase due to overall industry growth. Specifically, demand for high-efficiency c-Si modules is set to increase along with the deployment of constrained-site solar PV projects. Much of this demand is coming from the expansion of projects in Japan, NPD Solarbuzz says.

A report by IHS says that demand for high-efficiency crystalline modules is prompting PV suppliers to invest in new technology upgrades in order to enable higher-efficiency products. Such equipment is also critical in allowing PV manufacturers to differentiate their products, IHS says. R