all home built solar system

Author	Message
wiseguy Guru Joined: 21/06/2018 Location: Australia Posts: 1254	Posted: 11:15pm 25 May 2021         nickskethisniks said   There is a schaltbau dc relay between solar panels and mppt controllers, and I've got 2 more recycled but they draw a lot more current compared to those kilovac relais. For interest if you havent done the calculations here is what the Kilovac requires. The 24V Kilovac has a 40 Ohm coil so running from 24V for pull in draws (24 x 24)/40 which is 14.4W, the "economiser" hold in at 7V becomes (7 x 7)/40 which is 1.2W I agree that during soft start with an older compressor style fridge, it might struggle to get going - I have no evidence to support this.  A relay that operates either after a time delay from soft start begin or at a voltage threshold (why not use 200 or 220 as the threshold instead of 180?) I think would help ensure a good solid start. If you could turn it on close to the zero crossing (some wetting current is desirable) would be nicer to the loads & could help extend relay life.   nickskethisniks said   Peter, for the first time powering up the nanoinverter, do I need to be careful when doing AC calibration? Can I expect overvoltage on the output or will it be ok? From memory I think the nano requires around 3V feedback to regulate the output. My approach is to temporarily apply 240V to the sense/feedback/transformer and wind the voltage adjustment for maximum ie 4V that is fed to the nano input (pin 19, A0) before applying power to the inverter, that way the output at first start up would be at minimum around 180V. I usually try to scale the feedback components so the maximum adjustment voltage range cant exceed 255/260VAC, Usually covering the range of ~ 180 - 255VAC. Edited 2021-05-26 09:19 by wiseguy