Inductorless Solar Charging Controller ?

[azaxi]

I have few of these T40 40A MPPT solar chargers. Tried one and seemed to work. Planned to use them for my solar setup but was not too impressed, compared to Renogy Rover 30A this produced about 30-35% lower current from same panel.

Opened one to see how easy would be to hack and read values from it, and was surprised with lack of power inductor. See pics. The plugin board with LCD has only MCU.

Would this be using PV wiring inductance for voltage conversion? This is a step down converter, what kind of step-down converter can use inductor in series with power source, without secondary inductor ?

UPDATE: found something, there is a relatively new design using parasiting cable inductance called S-Hybrid. It uses 3 switches which would correspond to number of power transistors (there are 6 but each pair is in parallel).

 

[rjenkinsgb]

It looks like just a PWM series current regulator?

If so, it could optimise for maximum load current up to the set voltage, but not do any power conversion - hence the much lower efficiency.

 

[azaxi]

You may be right. I bought them as MPPT and now I realize those I received do not have MPPT marker on them. The sales pic has MPPT and unit is exactly the same size as mine.

So basically I just been scammed, they accidentally sent me wrong ones.

And here I thought they are using the newest 3yr old tech utlizing parasitic wiring inductance )))

 

[fourtytwo]

I had to comment on this one as there is so much fakery and false claims surrounding MPPT & solar in general. Your quite right to look for inductors as it's pretty much the only way of doing efficient energy conversion. I am afraid this tomfoolery regarding wiring inductance is just another load of fakery. For a start the inductance required at any reasonable switching frequency (<500Khz) to avoid excessive switching losses is huge relative to an air cored wire not formed into a coil and secondly the resulting EMI created by such a device would blot out just about any reception of anything over a substantial radius and would have no way of meeting any nations EMC regulations with the possible exception of China (who I assume have none).

 

[Nigel Goodwin]

I had to comment on this one as there is so much fakery and false claims surrounding MPPT & solar in general. Your quite right to look for inductors as it's pretty much the only way of doing efficient energy conversion. I am afraid this tomfoolery regarding wiring inductance is just another load of fakery.

I would agree, it sounds like a load of rubbish - and even if it did work, it would be much less efficient.

I would also say, they didn't send the wrong ones - he was scammed - typical of Chinese suppliers. But if you got them from Aliexpress or similar, then they will refund you the money - they are well aware that a number of their suppliers are scam artists.

 

[azaxi]

Thanks fourtytwo and Nigel Goodwin.

I got these from Amazon.ca, still within 30 days, so perhaps will return. Bought last two of the listing, they were $21+tax/each - delivered next day, I thought wow perhaps a pricing error, what amazing deal. They look nicely built inside, unlike other electronic products from China, fiberglass PCB, terminal blocks and heatsink correspond to advertised currents. Ad on Amazon says MPPT, pictures have MPPT marking, but as you can see on my pictures, the ones I received do not have MPPT marking. Otherwise everything else is same. Perhaps there are two products in same case.

Going to stick with Renogy for now, their Elite 40A is similar size as T40 so I am curious how Renogy fit 1kW inductor in that size. Elite has RS485 Modbus interface and protocol description is available on Renogy forums.