Inverter Revamping Leads to an Unexpected Surge in Productivity

2nd May 2017 by: Solar 21

Last summer we revamped the solar inverters in our three Italian PV plants in an effort to improve productivity. We have now completed inverter revamping in three more plants and the results speak for themselves.

The inverter is a critical part of solar PV technology because it converts the current output of a PV solar panel into the specific type of current necessary for injecting into the electrical grid (utility-frequency alternating current).

Aging inverters

The inverters installed in the heady days of the so-called installation race of 2010/2011 when Italy’s generous feed-in tariff for solar energy was announced, were not always of the highest quality, or came with the best warranties. Now, six or seven years on, they are underperforming in many cases.

As anyone involved in the solar industry knows, the fact that we are paid a tariff for every KWh injected into the grid means that when any part of the plant is not working at its optimum we lose money. This reality drives our asset management strategy.

Inverter revamping has other advantages

Revamping a solar PV plant obviously involves upgrading the original system with the latest models but it has other advantages too: It gives us the opportunity to tackle any design or technological limitations that may have dogged a plant in the past (we purchased operating solar plants rather than developing them from scratch so we inherited some design flaws). The revamp also gave us the opportunity to simplify the design – we have replaced four inverters with one modern one.

Always looking for ways to boost productivity

The inverter revamping is just one of a series of optimisation activities that Solar 21 is carrying out to boost the productivity of our PV portfolio. For instance, we are currently evaluating the revamp of PV modules for other plants where modules have shown hotspot issues causing, on average, a 40% reduction in their power output which could potentially lead to a loss of approximately €30,000 per year per site. Addressing this issue will be a priority for us.

In addition to larger projects such as inverter revamping, we actively look for ways to increase revenue by identifying and analysing profitable optimisation opportunities in the day-to-day management of the assets. We do this by:

• Improving technical performance

We remotely monitor and analyse data on the asset output so as to immediately identify any production ratio drops.

• O&M supervision

We have developed strong, collaborative partnerships with reputable O&M (operations and maintenance) providers. We take cost-effective decisions while understanding the scope of work required.

• Contract management

We are negotiating existing contracts to reduce current operating expenses.

And now for the productivity results!

We based our decision to go ahead with the revamping on a conservative evaluation of a 3% increase given the technical specs of the new inverters, but the results in the last few months suggest a 10% increase in production.

This is an excellent result given that nothing else changed; the modules are the same ones that were installed initially, and though they are guaranteed to work for 20 years, we would expect a slight degradation due to their age (six or seven years old).

I am pleased to report that the new inverters are working beautifully, showing an availability of 100%.

We are in this for the long term

We have taken a long-term view. We need these assets to produce at their optimum output for the remaining term of the 20-year incentive scheme and we understand that to achieve that, we need to engage in proactive asset management, which in turn assures our investors of a good return. I should also say that having a collaborative partnership with a good O&M is critical to the achievement of our goals and we must thank BFP group for its excellent service in that regard.

Silvia Raineri is Energy Engineer at Solar 21.