The best solution to repair at the uncertainty of the incentives scheme experienced recently in Italy is to increase solar productivity hours during the year: this is the experience of Tredi Elettronica, the owner of one 1MWp plant near Piacenza where energy output reached 1740 hours in one year, a high number compared with productivity of other plants nearby, with an average of about 1000 hours per year.
That is a photovoltaic plant using solar tracking systems, on a five hectares field, with 98 biaxial solar trackers, each one with an array of 72 square metres and at a distance of 20 metres the one from the other.
The plant, connected to the grid in 2010, has been designed with an Inverter for each tracking pole, to have the control on any single part of the plant and to be able to find the exact point of failure.
The plant has 98 Inverters: 48 of them are KP100L from Omron, with efficiency peak 97,5%. The other 50 inverters are from another supplier, with a higher peak efficiency (98%), confirmed by real measurements on field. At that time Omron did not have enough pieces on stock to satisfy the whole request.
Daniele De Gaspari, the designer of the plant, is the owner, together with his brother, Danilo de Gaspari, of Tredi Elettronica. After five year of real experience, he says: the efficiency of a photovoltaic plant should be measured in a period. In my experience the portion of the plant with the Omron Inverter produces in one year about 5% more energy output. Thats why we are going to install the Omron Inverter on the whole plant replacing step by step the non-Omron inverter present, to have a higher number of solar productivity in one year
The reasons why the portion of the plant with the Omron Inverter has better performance are:
The wider range of input voltage (225-850 Vdc), thanks to which the Omron Inverter can start producing energy very early in the morning, even if voltage is low, and switch off later at evening.
The 3 MPPTs, which provide three different inputs of the Inverter which can be connected to three different strings and then guarantee the best productivity at each time of the day, even early in the morning or late in the afternoon when the shadows of the other arrays of the plant are present.
We have a very good relation with Omron, which has high quality products and a very professional post-sales service. The inverter is the heart of the PV plant, and when the plant uses tracking systems the inverter works for many hours a day. Failure occurs, but Omron has a very efficient post sales service and failed inverters are back in field in 2 or 3 days.
Incentives are not stable, but our plant has a very good design and this is the best way to keep a good return on investment. Our winning choice to have a solar tracking system, with one inverter for each array, gives us the opportunity to have only 1 % of productivity downgrade in case of inverter failure, always solved in a very short time.
