"What market requests more is high skilled value after sales service
What is the best solution for the obligatory nature of inverters with transformers only in Spain?
We need to offer a wide portfolio with low frequency transformer inverters up to 100 KW. Another likely solution would be high frequency transformer inverters, however, this technology has a technical limitation for power above 30 KW, and you can only set units in parallel which brings general reliability problems to the PV plant. Moreover, Spanish regulation requires the output nominal power of the inverter to be matched with the defined power for the installation; therefore, you need to offer inverter solutions at many different powers. Our SolarMax portfolio brings complete solutions by having transformer inverters within this range at: 20-25-30-35-50-80-100 KW.
Likewise, a few months ago, the Ministry of Industry released a Technical Note to define when transformerless inverters can be used within Low Voltage PV installations. Our string inverters S and MT serial inverters have been tested and successfully passed the test defined in this document and this would also allow the use of these transformerless inverters for LV installations in Spain.
Central or decentralized inverters? How are they evaluated before deciding on the option?
This is a very old debate, since both solutions have pros and cons and it depends a lot on the installers’ experience and preferences. On one hand decentralized inverters give more flexibility and redundancy, on the other hand, centralized inverters show a simplified AC cabling and installation and also have a higher overall reliability.
It is important to note that big land installations done with single phase inverters are over, as it was done in the past. The main reason is the P.O.12.3 dip voltage request for PV installations over 2MW since single phase inverters show serious hurdles to fulfil this REE normative.
How can you assure the quality and the security of the investment of decentralized systems?
After sales for small inverters should be based on a direct exchange system, since it enhances the availability ratio. Therefore, the inverter manufacturer chosen should be able to serve any exchange unit in a maximum 24h-48h. Likewise, decentralized inverters should be remotely monitored, as is usually done with central inverters.
It is also important to take into consideration the P.O. 12.3. compliance for small inverters, as depicted above, in case of use in big installations.
New concepts of interconnection, maintenance and spare parts. Is there a more open market now?
This is an investment to last above 20 years, and moreover, inverters are usually the most critical part. Therefore, what market requests more is high skilled value after sales service for having always inverters working properly and well fitted, rather than spare parts to act punctually by someone on it.
Could you tell me about new Technologies and microinverters?
This is a very interesting approach of having inverters embedded into the panels, however, at the moment it is not yet in a mature stage and there are some start-up companies partnering with PV panel OEM’s to come to a common solution. The main issue today is economic and also the after sales service approach.
What are the parallels of developments in the German industry, with the solutions adopted in Spain?
E-On in Germany and REE in Spain show similar constraints in terms of PV energy integration into the grid, since they have to fit their schema to a decentralized power source model. Therefore for instance, fault ride through request pointed out within BDEW German directive is not so different to P.O. 12.3 REE normative. Likewise, reactive/active power control injection is also a topic to get under control for both utilities.
On the other hand, for instance, German market does not show any kind of reluctance for integrating transformerless inverters.
Does Sputnik have solutions for maintenance?
We provide our premium service package “MaxControl”. Under this program, our own Sputnik skilled personnel provide any kind of maintenance or after sales service requested to guarantee a minimum of 97% availability for any inverter throughout the year. It gives all the drivers needed to rely on the right inverter working during all the PV plant life.
What are the particular needs for inverters as part of off-grid systems?
Inverters for off-grid or stand alone systems need specific firmware for balancing the battery system associated, and also, there is no grid to be synchronized. So, those inverters must be specific for an off-grid solution and grid connected inverters do not work in such applications.
What is Sputnik’s solution for overvoltage?
A year ago, Iberdrola launched a statement about overvoltage issues with some inverters which could cause damage to PV counters. They proposed fulfilling an overvoltage curve defined by ITI (CBEMA) to get those surges under control. Sputnik applies over voltage monitoring and protection at AC side which allows SolarMax inverters to fulfil this ITI curve.