The solar sector has become a mature industry within a decade, and all stakeholders have a clear understanding of the different technologies and components used in a solar project. The inverter, one of the key components of solar projects, has witnessed several interesting developments. This article charts the key trends in the solar inverter market…
Higher capacity of inverters
Inverter capacities have been on an upwards trend. A decade ago, the biggest inverter available had a capacity of 100 kW. Now there are 5 MW central inverters. For string inverters, the biggest capacities available a decade ago were in the range of 10-15 kW. Now string inverters for the commercial and industrial segment are in the range of 100-110 kW. Technological advancements in the semiconductor space have prompted this change.
Shift from central to string inverters
A key trend in the sector has been the increased focus on balance of systems (BoS) to maintain a high return on investment. To this end, inverters can play a significant role given that they are smart technology that generate a lot of data. Efficient utilisation of inverters can assist in reduction of total operations and maintenance (O&M) costs. String inverters, for instance, generate data on the amount of maximum current a string is able to draw from an array. This assists in deciding whether O&M activity is necessary or not, considering the weather conditions in that particular area. With this, the optimum frequency of module cleaning can also be decided, resulting in savings on O&M costs.
The biggest challenge that the industry faces for inverters is constant breakdowns, leading to loss of power generation. Because of this, there has been a shift to greater use of string inverters. Other key advantages of string inverters include their ease of design and O&M. With this technology, even breakdown time can be minimised, resulting in greater revenues with enhanced power generation. With competitive tariffs being discovered, there is no room left for developers to lose out on this crucial revenue.
Another concern with central inverters is that they mostly need to be upgraded or repaired and not replaced, as the raw material used for making them keeps on changing, making old inverters obsolete. Therefore, systems that can easily adapt to the available technologies in the market are needed. String inverters, again, are a preferred alternative, as they are more flexible and easily replaceable.
Considering a central inverter of higher capacity, the per watt price is always lower compared to that of a string inverter. And the capex of string inverters is around 2-3 per cent higher than that of central inverters. However, given the higher generation yield and lower O&M costs possible with string inverters, the capex gap can be recovered in the long run.
Upgradation of inverters with high watt peak solar panels
Another key trend in the sector has been the upgradation of the size of solar modules. Inverters thus need to have the capability to synchronise with high watt peak solar panels. Earlier, the maximum operating current of a PV panel was close to 9 ampere. With bifacial technology, this was increased to 11-11.5 ampere. Now modules are being built with 210 mm wafers, which are able to generate 17 ampere of current. To deal with this trend, inverters also need to be upgraded.
Introduction of arc-fault circuit interrupters in inverters
Inverters will also need to become smarter, as they will be the key information generators for solar projects. In addition, inverters will need to become safer, with an increased focus on enclosures to ensure that they operate even in harsh climatic conditions. Another key focus area would be the introduction of arc-fault circuit interrupters in inverters, which will be able to determine whether an arc fault is at the inverter or the module level. This functionality can trigger an alarm in 0.05 milliseconds, allowing the inverter to disconnect the circuit. This will be especially useful for rooftop solar projects, which have the most trouble with addressing arcs at the DC end.
All in all, the inverter market is experiencing many dynamic developments to become smarter and safer and more flexible in adapting to the developments in the solar sector.
Based on remarks by Idrish Khan, Chief Technology Officer, Solis, at the “BoS for Solar Plants” virtual conference organised by Renewable Watch
