Solar Patent Wars: Tigo Takes On SMA

Solar power conversion and storage product manufacturer Tigo Energy Inc. has filed a lawsuit against inverter giant SMA in relation to Tigo’s rapid shutdown technology patents.

Tigo Energy manufactures inverters and optimisers, the latter a form of Module Level Power Electronics (MLPE) also known as Panel Level Optimisation (PLO). An optimiser is a small box of electronics installed on the back of a solar panel or attached to the mounting rail beneath it that enables panel level monitoring and ensures the current provided by the panel is always optimal for maximising energy output.

Optimisers can be added to one or all panels in a string. They can be handy in installations in which only a few panels are impacted by shade, minimising the otherwise significant impact on the entire string.

Tigo Energy Inc. was founded in Silicon Valley, California in 2007 and has accumulated more 115 patents relating to various aspects of its optimiser technologies. Some of these patents relate to rapid shutdown technology that reduces the voltage of rooftop PV systems in the event of an emergency at the panel level.

In the USA, NFPA 70, National Electrical Code (NEC) is the benchmark for safe electrical design, installation, and inspection. It requires solar systems include a rapid shutdown function to reduce shock hazard for emergency responders¹.

Tigo’s rapid shutdown solution for residential applications for its TS4 line of optimisers consists of two hardware components:

• Rapid Shutdown Device (RSD), which stops the voltage at the module level. The shutdown command can be issued over PLC (Powerline Communication) or wirelessly with the initiator.
• Rapid Shutdown Initiator. Often installed in the solar inverter wirebox, it initiates the rapid shutdown process when the keep-alive signal it transmits is no longer detected by the RSD.

Yesterday, Tigo Energy announced it had filed a lawsuit against SMA Solar Technology America LLC, alleging SMA and some of its suppliers have infringed on six patents² relating to innovations that comply with US rapid shutdown requirements.

“The complaint was filed in the United States District Court for the District of Delaware and includes all SMA legal entities in the U.S. and around the world,” said Tigo.

SMA Silent (So Far)

An interesting twist in this situation is SMA Solar Technology AG acquired a 27% stake in Tigo Energy back in 2016 in order to upgrade its portfolio in the area of MLPE. SMA stated at the time:

“Around the world, over a billion solar modules have been installed that cannot be individually monitored. With this stake in Tigo Energy, we can for the first time give all solar modules intelligence—in both existing and new plants.”

There were a couple of hiccups following this in terms of compatibility.

Usually in these patent wars, the company accused of infringement is pretty quick to pump out a press release generally denying any allegations and pledging to vigorously defend against them. But at the time of writing – as far as I’m aware – SMA hasn’t issued any public statement. This post will be updated if/when SMA does.