The manual states 100mm clearance above and below the charge controller. As it’s convection cooling and not forced cooling the clearance must be important. During an upgrade with and additional battery yesterday I was sent a photo showing about 30mm clearance at the bottom (combiner box to MPPT) I immediately emailed the installer and asked for it to be rectified before cables were installed. Correspondence confirmed it would be addressed today. There are no obstructions above. Install completed today and I’m estimating the clearance at the bottom is now around 50mm. Unfortunately I only saw the image this evening. Email duly sent to the installer office and waiting to see what happens.
Previously a different installer covered the bottom of the charge controller with trunking to make it look nice. I had to cut the trunking away to rectify and enable the controller to cool itself. This is the same site so I’m a bit sensitive about cooling the controller.
Am I being too careful here? (Helping a widow take care of her plant from a distance)
Now I’m told that there is the required 100mm clearance but it’s between the actual bottom of the 250/70 heatsink and the combiner box below. The reduced clearance measured at 48mm is because of the wire box and the wire box doesn’t matter. My 1969 high school physics says it has to be taken into account as the wire box is an added accessory. MPPT WireBox - Tr - Victron Energy
Those MPPTs run quite hot. If you cannot adjust the clearance then an alternative would be to buy an off-cut of sheet aluminium and mount that between the MPPT and the wall. In my experience that brings temperatures down by about 20 degrees.
Thanks Pierre. I’ve had a reply from Victron and they confirm 100mm clearance below the wire box itself. I will now give this information to the installer. I don’t want to alienate the installer because his work is excellent other than this wire box issue where he is convinced that it has no shrouding effect. There is no reason not to move the controller up but I think he is resisting because there is no spare slack in the battery cables. The aluminium plate is simple and easy enough to do but I want the clearance as well.
If you space the MPPT away from the wall by say 40mm you won’t have to drill new holes. Just use longer screws and a spacer. I would cut some copper tube into 40mm spacers. They will then sit “proud” of the conduit. May look a little stange though
It took a moment to work out what you meant. In my case the obstruction below is a combiner box which would mean spacing the MPPT > 100mm away from the wall to clear the combiner.
I don’t want to “Make a plan” the clearance issue was raised as soon as the MPPT was installed before wiring. They did move it up a few mm to what is shown in the image but that was not enough. The installer says I’m not an installer, implying I’m ignorant of how it should be done, and assures me it’s good as is. I want it moved. He was called in as an official Victron installer to rectify the previous official Victron installers work.
This has got messy. It’s very difficult to get the needed information from Victron to show the Victron approved installer who resorts to ad hominem attacks and appeals to authority (his)
It does however make the window through which air is drawn smaller. But also not quite as much as you might think, since it also doesn’t block the sides.
In normal convection cooling, air flow rates are really low.
Now… I looked everywhere in the documentation but nowhere does it seem to address the spacing when using the wirebox. So this is a bit of an opinion, not stated fact. But I think you can probably get away with less than 100mm below the WireBox. The WireBox itself, the large one, is about 47mm high. So if there was 100mm to begin with there should still be more than 50mm, with the sides open and no real impeding of airflow.
I also see plenty of sites where trunking is fitted right up to the MPPT, so that the only air flow is via the sides anyway.
Again, I am no engineer, and I can probably spend some time to find one who knows, but my gut feeling is that the WireBox doesn’t obstruct it all that much.
What you can do, is accept it on his authority, and then monitor it and look for clipping. Those MPPTs are designed to run at 100% up to 40°C, and will then start to clip peak current. If it doesn’t clip, then you’re fine. If it clips (and removing the WireBox changes that), he comes back and moves it.
The manual states a minimum clearance below (and above) for optimal (best) cooling. Temperature affects the operation and design service life of the unit so it has to be cooled to operate effectively.
Any obstruction closer than the specified 100mm to the inlet of the heat sink will impede airflow as the “engine” driving the airflow is very weak (convection) It needs all the help it can get.
The plastic cover of the wire box is not the real issue but the mounting plate to which it is affixed which projects down reducing the specified clearance to objects fitted below it.
Victron don’t specify clearance with or without a wirebox so the logical conclusion is that whatever form the installed MPPT takes the clearance should be 100mm.In essence, maintaining unobstructed airflow at the inlet of convection cooling systems is crucial for optimal performance and component longevity
If it’s a working system then check the temperature of the unit when its working hard.
I do this by feeling the heatsink with my hands. Only if it’s getting really warm/hot do you need to fuss about it.
Also if your setup is in a small room/cupboard then an extraction fan is a good idea.
The previous “Victron” installer covered the bottom with trunking and I had to cut it away as it was overheating. The current “Victron” installer was told explicitly about the previous problem and our clearance requirement. He fitted it with 50mm clearance and this was pointed out before it was connected. It was moved but not enough as you can see from the image. I can see three faults in that image as a layman.
Thanks for taking the trouble to find out. I agree 100% with the engineer that the wire box itself does not reduce airflow significantly, however that has never been the issue. The issue is that the wire box significantly reduces the required free air gap dimension below the unit if there is an obstruction. Without the wire box the required air gap is 100mm. With a wirebox on this unit the required free air gap is <60mm (side air entry on one side is blocked by trunking in this case too)
Mostly I take the position that the customer’s preference should be heeded as much as possible (aka, the customer is always right, whenever he is asking for something that’s doable). So I don’t like hearing that the installer is making this an argument over who knows more.
I’m also pretty confident that the mentioned free air gap is fine, but that’s not really the issue here.
