The landscape of the inverter market is changing. Falling equipment costs and greater price parity between central and string inverters is giving project managers more flexibility than ever to select inverter architecture based on the particular characteristics and constraints of photovoltaic (PV) sites.
Recently, at the PV Power Plants Turkey conference in Istanbul, I had the chance to moderate a panel in which representatives from major inverter manufacturers Bonfiglioli, LTi REEnergy and SMA sat down to discuss the evolving economics of the inverter market. The panel was initially set to discuss where there are opportunities for further reduction in “day one” costs, i.e., the price of purchasing and installing inverters during PV site construction. However, the conversation quickly took on a more expansive view focusing on inverter reliability over the lifetime of a system.
All three representatives brought their own perspectives on improving inverter reliability. Several key takeaways came out of this. First, while falling costs are certainly a positive trend, manufacturers should not overemphasize lowering costs in a “race to the bottom.” Second, there was agreement among all three manufacturers that increasing availability and lowering operations and maintenance costs should be a core R&D initiative. Lastly, much emphasis was also placed on improving “plug and play” and inverter replacement capabilities to maximize uptime.
Turkey proved to be a highly relevant setting for the debate surrounding the prioritization of lowering day one costs versus improving reliability. Like many countries looking to spur growth in the early stages of solar development, the country has instituted feed-in tariffs for solar energy production. This strongly incentivizes maximizing output and minimizing the costs associated with getting PV sites online.
The presence of tariffs will be motivation to produce as much energy as possible out of Turkey’s expanding solar infrastructure in the short term. While this mentality is understandable for fledgling solar markets, the entire lifecycle of a PV site must be considered in order to help the market mature and become a significant part of the energy sector. In the long term, PV power plants must be viewed as decades-long investments. This is why inverter reliability must remain a top priority. Reliability must not take a back seat to cost reductions if Turkey and other emerging solar markets want a viable solar industry.
Distributed Power Optimization
Yet, delivering lower day one costs and inverter reliability prove not to be mutually exclusive. Through the efforts of the HDPV Alliance – an industry group that Ampt and several of the inverter manufacturers I met with in Turkey belong to – a new approach to inverter architecture is available to project developers. Distributed Power Optimization (DPO) delivers advantages throughout the lifecycle of a system: lower day one costs and greater output and reliability in the long run.
DC optimizers are fundamental to DPO architecture. DC optimizers are power converters that are distributed throughout a PV system. By applying voltage and current limits to each string of PV modules, the DC optimizers enable central inverters to operate within a higher and narrower voltage range than is possible with traditional inverters. With DC optimizers in a PV system, the rated power output of central inverters increases by as much as 60%. In turn, this allows sites to implement fewer inverters, significantly reducing initial equipment costs. In this way, DPO systems achieve the goal of lowering inverter costs without having to sacrifice reliability.
In addition to lowering upfront capital costs of PV plants, DPO also maximizes value over the long term thanks to its higher maximum power point (MPP) tracking resolution. By placing DC optimizers with MPP trackers on each string of PV modules, systems deliver 2 to 4% or more energy than traditional large-scale PV systems. That means greater revenues over the life of the system and higher returns.
While cost reduction is a core consideration for Turkey and similar early solar markets, reliability is also a mainstay of discussion. Experienced global players are encouraging developers in these younger markets to view PV installations less as a short term opportunity to cash in on high incentives and subsidies and more as an effort to build a sustainable, clean and technologically-advanced energy sector. Inverter manufacturers will have a large role to play in this effort as groups like the HDPV Alliance continue to develop innovations that reliably generate more energy while also saving on system costs to serve these emerging markets.
Written by Levent Gun, CEO of Ampt, a provider of power conversion technology designed to reduce the cost and increase the efficiency of solar energy generation. Ampt is a founding member of the HDPV Alliance, a solar industry consortium of companies devoted to the development and adoption of distributed power optimization solutions that lower the cost of solar energy.