Solar Charge Controller running HOT

[JT87]

While camping during a sunny day in Anza Borrego, I noticed that my Solar Charge Controller was very hot to the touch. Hot enough that I could keep my finger on it for only a second.


A sunny day in Borrego may be an extreme situation in terms of solar energy hitting the panel on top of my van. Still, it does not seem correct that the solar charge controller should get *that* hot under any circumstances. I could understand it getting warm.


Thoughts?


THE EQUIPMENT:
“Blue Sky Energy” MPPT Solar Charge Controller, model “Solar Boost 3000i.”


The charge controller was installed by Sportsmobile West, but I did NOT have hem add any solar panels at the time.



See photo of install charge controller location.





Later, I mounted a Renogy RNG-300D panel to the roof of my van and wired it to the solar charge controller. The panel is a Renogy 300W Monocrystalline Solar Panel.


https://www.renogy.com/template/file...-300D_spec.pdf

[1der]

Your solar panel is just above the spec range for the 3000i controller both in terms of watts and voltage. A 60 cell panel is allowed up to 290w & Vmp of 31. Your panel is 300w and Vmp of 32.25. Add that you were in Anza Borrego w strong sun and you are asking your 3000i to handle a lot of current. Especially if you had just driven and your batteries had been receiving a charge from your alternator.

The solar panel is sending current to the SContoller anytime there is light on the solar panel. Strong light equals lots of current. The SC will use whatever current necessary to charge the batteries and run the running 12v loads but it has to dissipate the unused current somehow and that is via heat. The 3000i is mounted up high in an enclosed space with virtually no airflow.

My Midnite Solar The KID has a huge heat sink visible to dissipate heat. Doesn't look as "nice", though, but some situations require function over form.


I would be very cautious with your system. Please check all your electrical connections and wiring coming into your controller. Unwanted resistance at a fuse connection can heat that plastic block up to the point of melting.

[JT87]

1der, thanks so much for your very helpful post!


I wasn’t aware that my panel was beyond the spec of my controller, until you pointed it out. Taking your advice, I removed the controller from the mounting panel and checked the connections behind it. From what I can tell, the connections into the controller seem pretty tight/legit, and the wiring is 10 AWG which seems adequate(?).



By the way, I found this language in the manual for the 3000i:


PANEL TEMPERATURE AND THERMAL PROTECTION
Internal power control devices use the front panel as a heatsink. It is normal for the front panel to become quite warm to the touch when the 3000i is operating normally. Front panel heating will be the greatest when the 3000i is processing either very high power or very low power. When mounted to a vertical surface with good ventilation, the 3000i can deliver full output in an ambient temperature of up to 45°C (113°F). If an over temperature condition exists, the 3000i will simply cycle on and off to keep internal temperature within acceptable limits.

The cycle on/off feature sounds like a nice safety feature, but the controller did not seem to cycle while parked/charging in Borrego.



I hear your caution, and I’m open to suggestions. Off the top of my head, thinking of some options:


1) Install a cooling fan into to circulate air through the cavity into which the 3000i mounted.

For example, this:
https://www.amazon.com/AC-Infinity-A...EUG/ref=sr_1_1

2) Upgrade the solar controller. From what I can tell (admittedly, I’m out of my league here), your Midnite Solar “The KID” MPPT Charge Controller would be adequate for the power of my system. I don’t mind the visual appearance of the heat sink and I’m more about function than form. However, the dimensions of “The KID” appear to be quite a bit larger than my 3000i. So, I’d likely have to relocate the controller…which potentially opens a can of worms.


3) Leave the setup as is, while being aware of the 3%-4% overload. I imagine (please tell me if this is wishful thinking) the excessive heat issue might be limited to situations like a cloudless day in Borrego or Baja, with a nice clean panel on the roof. Does my panel actually put out 300W or is that just the theoretical max? So, under normal use, when the panel is just a bit dirty from road dust and so forth, am I then within the spec of my controller? I don’t know.



I suppose could always cover a portion of my panel with a sheet or something, though that a bit of pain to do, particularly when the CCV top is already up.



Thoughts greatly appreciated.

[REF]

Yup....an upgrade to your controller is in order and probably the easiest route, you can always countersink or mount a new controller so that it’s sunken into your overhead panel, but I wouldn’t enclose it, so as to provide it with as much heat dissipation as possible.
Many, including myself, have upgraded to a Victron unit, certainly smaller than the Kid unit. I got the Bluetooth capable 100/30, good for up to 460W I believe. I had your BlueSky’s little brother, the SC30, mounted in the same location, that ended up failing and created a similar scenario as you with excessive heat, except mine wasn’t charging at all.
When I upgraded to the Victron unit, I relocated it to under the bench seat, with more airflow and closer to the battery bank, and covered the hole left behind in the overhead console with a plate, where I mounted the optional remote charge controller monitor alongside the Victron battery monitor, only because I like redundancy and a hard mounted visual, even though both are Bluetooth capable. But in that scenario, you’d have to swap your solar input wires and battery lead wires.

[boywonder]

Originally Posted by JT87

2) Upgrade the solar controller. From what I can tell (admittedly, I’m out of my league here), your Midnite Solar “The KID” MPPT Charge Controller would be adequate for the power of my system. I don’t mind the visual appearance of the heat sink and I’m more about function than form. However, the dimensions of “The KID” appear to be quite a bit larger than my 3000i. So, I’d likely have to relocate the controller…which potentially opens a can of worms.


3) Leave the setup as is, while being aware of the 3%-4% overload. I imagine (please tell me if this is wishful thinking) the excessive heat issue might be limited to situations like a cloudless day in Borrego or Baja, with a nice clean panel on the roof. Does my panel actually put out 300W or is that just the theoretical max? So, under normal use, when the panel is just a bit dirty from road dust and so forth, am I then within the spec of my controller? I don’t know.

Upgrading the solar controller capacity still dissipates the same amount of heat from the controller heat sink when fully charged....but a larger heat sink will run a bit cooler temp-wise.


As a general rule of thumb....at a temp of around 135F you can keep your hand on a heatsink for a few seconds....



I personally wouldn't worry about the few percent over spec you are with your panel, since the panels are rated for max output under laboratory conditions....or the sun shining in Antartica surrounded by clouds. Have you ever seen current flowing above 30 amps when your batteries are low (bulk charge)?



I'd say be happy....lots of electronics run that hot....like class A audio power amplifiers...they are large heaters that make a little sound.

[moorefc]

Why not check the airflow in the back side to ensure it is an open space, and give Blue Sky a call.....Did you see the output current when hot, or what is the max you have seen? Temperature is the key....and as boywonder said, PV max output is really a lab test output with cool solar cells and lots of lumens...Deserts are hot, so the output is reduced from the lab (25degC 1000w/m2)....Renogy does not show temp vs output in their spec sheet, but the curves exist...

[JT87]

Thanks for the great responses! I was away in Baja for a bit and unable to reply.


Anyway, I buy the argument made my boywonder that, in the real world, my setup is probably within spec. And, for that reason, I don’t feel an urgency to change things right away.


Having said that, I don’t like that the solar/battery system in my van is such a mystery to me. SMB built the interior of my van. The downside to having them do the build is that I don’t always know how/why things were wired/configured. So, if/when I can find the time, I’d like to do REF’s idea of upgrading to the Victron unit (and relocating to under the bench seat) ---both for the benefits of increased ventilation/power capacity, as well as for the knowledge I’ll gain in the process.


Ideally, I’d upgrade the solar controller (and battery monitor) while ALSO upgrading my house batteries from AGM to Lithium. I’ve got (2) AGM batteries underneath my van, each 210Ah, weighing a combined 270 pounds. My van is nearing its load limit, so going to Lithium would allow me to shed weight without losing usable amp hours. A side benefit, assuming I run only a single lithium battery, is that the current location of one of my AGMs would become available (possible future location of a propane tank).


Am I crazy to consider such a project on my own? Which resources would you guys recommended I study before diving in to such a project?



Thanks again!

[REF]

Well now that you’ve dropped the magic word around here, at least to me.....Baja? where were you, did you drive down and what’s going on at the border, but maybe you either flew down or have a place down there, otherwise it looks like the border is closed to non essential and tourist travel, but we’ve heard that you’re able to get through and they’re not really stopping people. Looking at potentially heading back down if it looks ok for travel and closures aren’t extended.

[JT87]

REF,

I flew to Cabo for a last-minute surf trip, to catch the incoming south swell.

My understanding is that crossing the border on land is not encouraged, but also not forbidden. I think once you cross, the reality is that Mexico is dependent to a large extent on tourism, and so they are quite welcoming (as has always been my experience.) A few months ago, there were some towns (for example, Ensenada) through which you could not pass, unless you had some good reason to be there (resident, for example). So, you’d have to re-route to get certain places. I don’t believe those restrictions are still in place, but things could change quickly and without warning.



Crossing back in the US, as I understand it, is not a problem for US citizens, other than the prospect of long waits at the border.