Not so much a question as a possible answer to those of you worried about the temperature of your Victron MPPT.
I have a 6.4kW array driving a Victron 250/85 MPPT. By design the MPPT clips the array power at around 5kW which ensures the system reaches this level for more of the day as per several papers on the subject of clipping. I noticed fairly quickly that the MPPT got uncomfortably hot to touch particularly when operating in clipped mode. I don't know if the heat is additional and gets worse when clipping but that was my reasoning. Perhaps a Victron guy could comment?
I purchased the optional MPPT display which allows a readout of the internal temperature and found the device regularly hit over 50C. Not ideal although within the specification.
Many of you have queried solutions to the issue and my career in electronics tells me that high temperatures in electronics should be avoided if you can. Reliability drops off rapidly as T increases.
I spent a while looking for a fan solution but thought a simple test might point me in the correct direction wrt the amount of air I needed to blow over the MPPT.
I purchased from eBay two 50mm x 50mm x 15mm centrifugal cooling fans which each ran off 24V. These are pretty small but produce a good airflow. The cost of the two was just under £3.50 so definitely worth the experiment!! I've powered the fans directly from my 48V (nominal) battery with both in series. Of course the battery voltage is more like 53V so the fans are running a little faster and perhaps less reliably. I've also connected them via the MPPT relay which activates when the device is producing power so they are only on during the day.
As you will see in the photo I've placed them above the MPPT heatsink without any particular mounting as yet.
In the UK we rarely get air temperatures around 30C so I've yet to do a severe test but today we got up to 20C. I left the fans off and the MPPT got up to 51C. With the fans turned on the temperature dropped to 26C after an hour or so. Excellent!!
So, in conclusion, you don't need much of an airflow to dramatically reduce the operating temperature. I intend to purchase two more fans and more permanently mount the four of them above the MPPT heatsink.
Hope this helps.
