SunSynk 3.6kw Inverter cooling and longevity

[klondike]

Quick Intro

A brief word for any visitors who may find this post...

LetsChat is a forum primarily intended for friendly pensioner chat. Full members will see more boards than casual visitors or new members. You may or may not have any interest in that but perhaps you know a pensioner who may like to join us - if so please send them a link to https://letschat.club/ Should they join us they will be made very welcome.

Inverter longevity and efficiency.

The SunSynk 3.6kw inverter has only passive cooling. I believe the bigger models are fitted with fans.

As I use Solar Assistant I checked the temperatures under the Charts tab.



The Inverter Temperature chart shows steep temperature rises during import and forced export as well as when there is plenty of PV power being produced.



The temperature graph shows a curved rise during export and charging. Sometimes there was a double peaked top when the temperature rose above the green area. These seem to be signs of the inverter throttling back. For that reason I have set my Grid Charge Rate and Solar Export Rate at the lowest levels needed to complete those functions within the three hour time slots.

I have added a couple of 120mm PC type fans above the inverter heats sink on a timer covering those high use periods.



The fans which I bought from AliExpress run from a USB charger. The control in the lead had to go as it defaults to off when powered up. I mounted the fans above the inverter in a housing made from 3D printed fan mounts glued together and gaffer taped to the inverter. This serves its purpose but isn't getting a photo in this write up. Running it from a timer produces a big change in the temperature graph.



Those curves still show up so maybe it's the BMS battery management doing the throttling. The rise between 05:00  and 07:00 is when the fans are turned off as they are again from 19:00 to 02:00.

I don't think the cheap fans are going to last being on half the day and I'm happy to let the inverter run a little warmer.

To that end I bought a in thermostat control like the one pictured.



This has resulted in a decent reduction in temperature except during charging which still runs a bit high.



To reduce that temperature rise when there is only a modest amount of charge needed which can be spread out over a longer period I have added an extra automation that reduces the maximum charge current. This just gets set at 02:00 and reduces the charge current based on how much will be put into the battery based on the solar estimate. It is set back to a high value at the end in case there is an Octopus free power day when a fast charge will be needed.






Guest posts on the topic may be made here - https://letschat.club/index.php?board=28.0