“Central inverters still offer the best LCOE”

You have announced the release of a new PV3750 high-power central inverter. What’s your schedule regarding availability?

The official launch is at Intersolar Europe. We are planning to finish the certification of all the versions like the IEC but also the UL versions. That will be somewhere in the last quarter of 2019, but will accept orders earlier than that.

Where are you planning to market the product?

The PV3750 is addressing the large utility-scale market. We will be addressing all global markets in which this type of application is demanded: We are talking about the countries in which large utility-scale plants are already deployed, or will be in the coming years, namely Spain and European countries, but also MENA and LATAM markets. At SPI 2019, we will present a new variant of the product for the U.S. market. Lest we forget, India and Australia remain in focus for us.

There are many EPC companies that have moved away from using central inverters. Why is Gamesa continuing to bet on its central inverter strategy?

Gamesa Electric is happy to see competition in the market. The fact that different technologies like string or central are proposed is good for customers in general. But having said that, our commitment to central inverter technology is very strong and we see that for the majority of utility-scale solar projects central inverters still offer the best LCOE. One point is the reduced capex. On this argument there is not too much debate.

However, opex is a little bit more controversial. Typical strategy of string inverter manufacturers is based on a “rip and replace” concept. According to Gamesa Electric, this strategy does not guarantee a lower opex over the PV plant life expectancy. Materials costs could be similar for both technologies but labor costs would definitely be higher in the case of string inverters. And concerning yield, we at Gamesa do not share some of the messages conveyed assuring that PV plant production is higher with string inverters. Well on the contrary, we can certainly state the opposite in the majority of large utility scale projects.

Additionally, there are points which are not directly factored into the LCOE calculation, but are having a very strong impact on the economics of the plant. We have to talk about multiple technical risks associated with string inverters ,such as grid code compliance.

It may be easy to replace a string inverter, but what happens in twelve or fifteen from now? Will the equipment still be available in the market? String inverters are relatively new in the utility-scale market and nobody really knows how they will be behaving in the long-term. PV modules’ PID is another risk.

What are the LCOE advantages with your new central inverter compared to your existing model? Let’s take a project in Benban complex you delivered recently as an example.

The new version is more compact and we achieved a higher power denisty. The first consequence is a great reduction of the cost per megawatt. But higher power density is a way to reduce the number of units you need to install for the same power plant and this is impacting many other economical factors. If we are considering a 100 MW project based on 5 MVA PV stations, like the ones we used for the project in Egypt [Benban], we would need roughly 20 units for the whole project. Using the new 3.75 MW inverters on the PV stations allows us to use only 14 PV stations instead of 20. This is a 30% reduction in terms of units and thus has a direct impact on LCOE (less transportation and installation costs).

Doesn’t the higher power density have a direct effect on heat management?

The new PV 3750 includes a hybrid cooling system that is the key. We use air and liquid, in this case water and glycol. The liquid cooling system dissipates the heat from the IGBTs [insulated-gate bipolar transistors], semiconductors, and inductances. This is a new feature of the product and allows us to do something that is extremely important: 80% to 85% of the losses are removed through the liquid cooling system and this reduces mathematically the need for air exchange with the environment. Reducing air exchange in environments in which dust and sand are prevalent has its benefits. It also allows us to reduce the number of fans required to remove the heat, further lowering opex cost, as less fans need to be serviced or replaced. In addition, the PV inverter’s key components like inductances, semiconductors, and capacitors can work at a thermal regime that is very, very far from the limit. This allows us to increase PV inverter life expectancy within a normal context of 20-25 years of PV plants operation.

You mentioned a smaller skid onto which the PV station can be mounted. What are the advantages of reducing the footprint of the skid?

Footprint is helping a lot in transportation and logistics. If you reduce the footprint of the inverter, you can integrate two inverters with MV switchgear and MV transformer, auxillaries in a 40 feet plug-and-play skid and this is important to reduce costs in terms of logistics, contruction for better capex and O&M (opex).

Leading me to the next question: Why would I buy a complete PV station from Gamesa, rather than buying the parts separately?

If we deliver the complete PV station, the end customer can be sure that we are responsible for the complete PV station, in terms of warranty. Separate procurement, however, could imply warranty responsibility dilution. There are many things that can happen to a PV plant equipment, but with the Gamesa Electric PV station there will be a type of one stop shop. They will call us and we come and fix the problem.

Product reliability is a buzzword in the industry and it appears that the Gamesa is picking up on that.

Product reliability is part of Gamesa Electric’s DNA. The entire Gamesa Electric product portfolio pivots around reliability because we consider that it is critical for our customers, for the financial viability of PV projects and in the end for the solar PV business grwoth. In a time where many people only talk about cost reduction, mainly capex, at Gamesa Electric we really do be lieve on product reliability as the key to assure PV project sustainability over their life expectancy and in the end, contribute to drive down PV plant LCOE.

In summary, the key elements of Gamesa Electric PV 3750 impacting reliability are the hybrid liquid/air cooling system mentioned earlier, the use of tier one suppliers for critical components, the “easy to support” design concept and the fact that all units manufactured at Gamesa Electric are 100% tested at full power in our first-class test bench capabilities up to 10 MVA, reducing dramatically the probability of failure afterwards and being a real plug-and-play solution for our customers.