Current solutions for Module Level Shutdown (MLSD) compromise the reliability of systems by placing a vast number of sensitive electronics in the harsh rooftop environment. In a typical residential installation with 6 kWp, the number of power electronic devices needed rises from one (string inverter) to around 20 (micro-inverters or DC optimizers) - each device consisting of many electronics components, with every components being a potential point of failure in itself. On top of that, the number of connection points, which are the weak points in a system, increases by 2-3 times.
Since every component has a certain failure rate, as well as a 100% wear rate over time, it means that the reliability of systems is compromised. This can turn into a big liability for solar installers and potentially cause distrust in our industry.
In addition, PV systems with DC optimizers add components, complex software routines, and communication channels to a system. All these factors increase the noise levels they emit. These increased noise levels can cause nuisance tripping of the Arc Fault Current Interrupter (AFCI), compromising reliable operation of the system even without component failure.
Facing these reliability challenges, let's fix module level shutdown now and make solar simple, safe, and more reliable.
What to do when DC Optimizers Interfere
Arc-fault unwanted tripping survey with UL 1699B-listed products
Sandia National Laboratories
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