Solar Hot water system (thanks to forum, Warpspeed and others)

Author	Message
phil99 Guru Joined: 11/02/2018 Location: Australia Posts: 3127	Posted: 12:23pm 06 Jun 2025         Quote   the safe operating area graph on the datasheet gives the maximum current at 200V to be about 0.9A That is in linear mode where the IGBT has 200V AND 0.9A. As it is switch mode the IGBT gets 187V OR 7.8A. When it is off there is no current so no heat, when it is on almost all of the voltage is dropped across the heater and almost 0 across the IGBT. The heater gets hot and the IGBT doesn't. During switching the IGBT is in linear mode which does heat it somewhat. The less often it switches the less wasted heat and stress on the IGBT. With a low switching rate an oversize capacitor keeps the panel voltage stable.