Microinverters make a move on multi-MW solar power installations

Tildy Bayar

A microinverter from iEnergy

Photovoltaic (PV) microinverters, traditionally used in smaller rooftop solar installations, are being used in a 2.3-MW commercial rooftop installation in Ontario, Canada, supplier Enphase Energy (ENPH) has announced. The installation is the largest commercial rooftop project under the province’s feed-in tariff (FiT). Analysis firm IHS Research has called the announcement a milestone in the microinverter segment’s progress towards establishing itself outside its biggest market, the U.S., and outside the residential solar segment.

According to IHS’s analysis, PV microinverter shipments are forecast to exceed 2 GW in 2017 — and penetration into larger installations, along with success in new markets, will be the key driver for this growth. IHS inverter analyst Cormac Gilligan cautioned that if microinverters are unable to move into new markets and lower their dependence on the residential sector, their success will be tested.

The U.S. accounted for nearly 75 percent of the shipments IHS recorded prior to 2013, but in many states the residential market for microinverters is approaching saturation. It will be increasingly important, said Gilligan, that microinverters are used by the third-party/solar lease companies which are very active in the country. While solar lease companies such as Vivint Solar and Sunrun have used microinverters in limited numbers, other large companies like SolarCity (SCTY) have preferred to stick with string inverters as the more proven technology, he said. IHS does forecast that microinverters will be used in greater numbers by solar lease suppliers in the coming years as the technology improves and new models are released.

Microinverter use in commercial installations will grow by more than 20 times 2012’s amount to over 700 MW in 2017, said IHS, with revenues of more than US$200 million and commercial installations accounting for over one third of total inverter shipments in that year.

In 2012 the world’s second-largest microinverter market was France, largely due to market leader Enphase’s penetration, said Gilligan. In addition to the U.S. and France, the company currently focuses on Canada, Italy and the UK. In future, IHS projects Australia, Japan and the UK as very attractive markets for microinverters, as all have large residential markets and smaller commercial ones.   

Although microinverters are currently more expensive than traditional string inverters, IHS forecasts that prices will decrease by 10 percent per year, on average, which will contribute to increased commercial adoption.

What’s Driving Microinverters’ Success? 

Features such as embedded module-level monitoring, increased energy yield and improved safety have enabled microinverters to successfully penetrate the MW-scale installation space in 2013, said IHS, and these factors are expected to drive the projected growth in commercial uptake. All are currently important considerations when choosing an inverter for a solar project, Gilligan said, but they will also grow in importance.

For example, he explained, safety features are particularly important on a rooftop commercial solar installation in case of fire, so that fire personnel are protected. Indeed, safety was a key concern mentioned by the owners of the Ontario MW-scale system.

On larger projects, costs such as installation and servicing can add up. With microinverters’ module-level monitoring an installer or electrician can quickly discover which module is underperforming and replace it, saving on labour costs. And, Gilligan pointed out, in commercial locations such as cities and car parks it’s likely that there will be shading from buildings or trees, in which case the microinverter for each module can carry out its own diagnostic, optimising energy harvesting and helping to pay for the extra investment.  

Gilligan said microinverters will be used less in larger (2 MW and above) installations because for these projects it may not be economical, as installing a microinverter for each module may become challenging or time-consuming. “There’s no particular limit,” he said, “but I’d say up to around 250 kW is where microinverters become attractive. Thereafter, for 101 KW — medium-sized commercial installations — and above, there would have to be unique circumstances or customer demand.”

In the case of very large PV projects, he said, the customer or installer usually needs to be familiar with microinverter technology and have used it in the past — for example, in the U.S. and Canada where customers are already knowledgable and comfortable with it.

Key Players

Enphase, which has dominated the market to date, holds a 15 percent share of the total U.S. inverter market, and the company has grown that share year-on-year over the past few years, said Gilligan. Other key microinverter suppliers are Enecsys, SolarBridge and two traditional inverter suppliers, SMA (S92.DE) and Power-One (PWER), who have now entered the microinverter space. These larger companies are likely to have the bankability and resources to promote and offer a microinverter solution, said Gilligan, with the U.S. currently their biggest target market.

The traditional string inverter suppliers, he continued, don’t seem to be running scared just yet — although they have realised that it is important to offer a microinverter solution as part of their portfolio. “So if they have a particular customer or installer or integrator who’s comfortable using microinverters, they will offer one to them,” he said. “But equally, if they have an electrician or installer who’s very comfortable with the string solution, they’ll offer that. Different customers have different requirements and if there’s a unique situation — for example, a lot of shading, or angled roofs, or space issues where a larger inverter is impractical — it makes sense to use microinverters.”

 

Tildy Bayar is Associate Editor of Renewable Energy World magazine.
This article was first published on RenewableEnergyWorld.com, and is reprinted with permission.

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