Kent Whitfield from Nextracker raises and answers tough questions regarding hail and wind risks

Hail vs other catastrophic risks

Tough questions regarding solar power plants.:
1. How do you protect a PV plant from hail damage upon loss of utility power?
2. How do hail and wind risks compare?
3. What is the impact energy difference between mono-facial PV vs bifacial modules for cell breakage, and glass breakage? And front vs back impact? And how have module cost reduction efforts, with thinner glass and frames, affected module durability?
4. When should you turn into the wind, and away from the wind, to protect PV?
5. How does an owner and EPC responsibly manage extreme weather risk to ensure a single event doesn’t vastly exceed single-event insurance coverage?

Cherif Kedir, CEO of RETC (Renewable Energy Test Center), and Kent Whitfield, VP Quality and Reliability at Nextracker Inc., presented a landmark webinar which presented empirical lab, field, and detailed analysis that answered these and other questions. The session was moderated by Tim Sylvia of pv magazine USA and you can watch it and download the materials, with no registration, via the link below.

As Cherif explained, RETC has developed a test protocol, the RETC Hail Durability Test (HDT) sequence, which subjects different PV modules to a range of hail impacts with varying kinetic energies based on hail size, mass, and velocity at impact, with a variety of different impact angles. Insightful results were presented for a range of module designs.

So how do you protect a PV plant from hail when utility power is lost? With extreme weather FAIL-SAFE. Here’s how it work…every NX Horizon tracker features an integrated battery…when site power is lost, the tracker will rapidly (<1.5 min) move to a defensive stow position, typically 60 degrees...with zero operator intervention or active communication command. This functionality was recently validated on a utility scale power plant which lost its main transformer. Recently insurance rates have skyrocketed for PV plants, and some insurers cap "single event" losses so that the owners is liable for damage above the cap. Kent presents the data to support "both hail and wind risk need to be assessed, individually and together, and both a passive and active risk reduction plan must be in place as part of a comprehensive risk mitigation strategy". Extreme weather is increasing. It is essential to characterize the risks and apply technology solutions to mitigate them. Fantastic work and insights Cherif and Kent, it is an honor to be working together. Shug