Levelized Cost Of Energy Primary Driver For Choosing Right Solar Inverter Size

Inadequate inverter sizing can stress both DC and AC components, causing overheating issues

December 14, 2023


As solar power installations continue to grow, it has become crucial to optimally size the solar photovoltaic (PV) inverters to maintain their efficiency and performance to manage power generation in high ambient temperatures.

Mercom India hosted a webinar titled “Optimal Sizing of PV Inverters for Robust Performance in High Ambient Temperatures” on December 12, 2023, where industry experts discussed the factors involved in optimally sizing solar PV inverters for diverse locations and temperatures and achieving higher performance.

The panelists in the webinar were Dipak Patel, Director Technical, InSolare Energy; Ashish Upadhyay, COO, Essens Renewable; Sunil Panigrahi, Country Manager, Hopewind; and Anuj Mathur, Regional Manager – North India, Hopewind.

Priya Sanjay, Managing Director, Mercom India, moderated the session.

The experts discussed factors like the total cost, different geographical conditions, and grid stability that come into play when choosing the right inverter size.

Speaking about considerations for the optimal sizing of PV inverters, Upadhyay said that the primary driver for choosing the right inverter size is the Levelized Cost of Energy (LCOE), a decisive factor influenced by various aspects.

“The decision-making involves a trade-off where paying more for the inverter needs to be justified by increased energy yield. Consequently, designers and techno-commercial experts evaluate multiple factors such as module technology, string sizing, DC-to-AC ratio, weather data, and ambient temperature.” Upadhyay stated.

He added that in the Indian context, where high temperatures and relatively low overall costs and tariff ranges prevail, optimization and value engineering become paramount. The sizing of inverters is derived from the goal of achieving optimal limits. While an inverter with a ratio of 1.1 may be welcomed, the preference often leans towards maximizing inverter size, guided by considerations of LCOE and generation benefits.

Patel highlighted why InSolare used string inverters for optimal performance at its 70 MW solar park in Maharashtra. He said, “Given the diverse project capacities installed ranging from 2.6 MW to 14 MW, string inverters were preferred over central inverters. The decision-making focused on achieving the best fit for varied solar capacities, optimizing costs, and contributing to overall LCOE.

According to Patel, various challenges were addressed, such as the thermal behavior of modules and changing temperature patterns across the field due to soil types, stones, and climate variations.

“Tests and evaluations were conducted to understand the limitations of multi-power point trackers (MPPTs) of string inverters, particularly in power and current heating scenarios. In instances of technology overlap within one inverter, multi-MPPT features were utilized to optimize loading,” he added.

Mathur explained the relationship between the size of the PV inverter and its performance in higher temperatures, “When it comes to the size or power of a PV inverter, increasing its capacity amplifies the heat loss. This, in turn, requires more effective cooling to maintain optimal performance, especially in higher temperatures. To tackle this challenge, Hopewind has enhanced the heat dissipation system in high-power inverters. This improvement involves advanced cooling circulation technology, effectively managing heat from inside and outside the inverter.”

Panigrahi stated that Hopinwind’s 385 kW inverters have an advanced heat dissipation system and can maintain an output of 320 kW at 50oC, making them the highest-rated in the market.

He further added that the company’s string inverter is designed to handle the Indian grid efficiently. Specifically, it’s built to maintain a low structure tilt ratio of 1.3 to 3. This design allows their inverter to operate smoothly in the conditions prevalent in India, addressing factors like heat and grid quality.

Inadequate sizing can have severe consequences, imposing stress on both DC and AC components, particularly on cables, leading to potential overheating issues. Proper inverter sizing is emphasized for efficient heat dissipation in cables, which is crucial for preventing operational challenges. Top of Form

The adaptability of inverters, coupled with effective heat dissipation systems, is a critical factor in maximizing energy generation and ensuring optimal efficiency across varying environmental conditions of the country, thereby reinforcing the integral role of proper inverter sizing in the success of solar projects.

You can watch the full webinar here.