Does the MPPT power the load in "The Minimalist Solar Package diagram"?

[Jacko]

Hi everyone,

I very much like the minimalist circuit wiring presented on this website, because re-using the fuse box for the MPPT makes it really compact.



However, I wonder if the MPPT in this case is not just used to charge the battery but also to power the load directly. Following is the diagram of the relevant pieces of the circuit, with a main switch to cut off the battery. For the load, I added the symbols of a LED (resistance + diode).



When the main switch is closed (left), the MPPT charges the battery, but doesn't it also powers the LED directly? Especially when the main switch is open: there will be no current in the wires connected to the battery (green), but it looks to me like there will still be current pushed through the LED by the MPPT.

If this is the case, is it problematic? I believed MPPT should only be used to charge batteries and not power loads directly.

 

[HRTKD]

Most MPPT solar charge controllers require a connection to the battery. No connection and they're "Off". In fact, there are significant warnings that you should never disconnect the connection between the solar charge controller and the battery while power is coming into the solar charge controller from the solar panels.

The solar charge controller could be thought of as powering devices on the circuit. Power from the solar charge controller doesn't go to the battery first and then come back out for consumption by devices on the circuit. Instead, the solar charge controller puts power into the circuit (a bus bar) where any device can consume it.

 

[Austan]

In the included picture, the load out of the charge controller (two screws furthest right) is not connected to anything. I'm not sure if I follow your question. If you are asking if power coming in is redirected to the load out (assuming there was one) then yes it powers that and the excess goes to the battery.

 

[Jacko]

Thanks for the quick answers!

Most MPPT solar charge controllers require a connection to the battery. No connection and they're "Off". In fact, there are significant warnings that you should never disconnect the connection between the solar charge controller and the battery while power is coming into the solar charge controller from the solar panels.

I see - so a main switch at this position is not the best idea then. Similarly if the fuse at the battery blows up, if I understand you correctly, this should be caught by the MPPT which will turn off automatically.

In the included picture, the load out of the charge controller (two screws furthest right) is not connected to anything. I'm not sure if I follow your question. If you are asking if power coming in is redirected to the load out (assuming there was one) then yes it powers that and the excess goes to the battery.

The load is symbolized with the resistance (blue rectangle) and a LED (blue triangle), connected to the fuse box and therefore also connected to the MPPT. Unless you're referring to the missing connection between the two +/- battery terminals of the MPPT - here I am unaware of the circuit within the MPPT itself, but it can be thought of as a powering device (a battery) as pointed out by @HRTKD

 

[Jacko]

In the included picture, the load out of the charge controller (two screws furthest right) is not connected to anything. I'm not sure if I follow your question. If you are asking if power coming in is redirected to the load out (assuming there was one) then yes it powers that and the excess goes to the battery.

Oh - silly me - I see the confusion now. The MPPT drawn here does not have load terminals, only battery terminals. As I now understand, battery and load terminals can both be seen as providing power (like a battery), but the MPPT detects and turns itself off in case there is no battery when connected on the battery terminals.

 

[Austan]

Yes sorry, I was looking at the picture only and not your schematic. As was pointed out, removing the battery connection should shut off the MPPT.