solar panels with diodes between each cell

FWC wrote:

rlw999 wrote:
There are specialty low loss "diodes" made for applications like this. They aren't traditional diodes but use a controller that switches a MOSFET. Essentially it acts as a switch that turns on when it senses forward voltage and off when it senses reverse voltage.

Here's an example that has a 26mV forward voltage.

Bypass diodes can use standard P-N or Schottky diodes, they are only forward biased (on) if a cell/string is shaded to allow the current to pass around the shaded cell. Definitely no need for a MOSFET 'ideal diode'.

They can, but as I said, there are specialty diodes made for applications like this that limit the power loss due to high forward voltage. The manufacturer even says that's why this product was developed:

Texas Instruments SM74611 Smart Bypass Diode is used in photovoltaic applications and provides an alternate path for string current when parts of the panel are shaded during normal operation. TI SM74611 Smart Bypass Diode has a lower forward voltage drop than PN junction and Schottky diodes. It has a typical average forward voltage drop of 26mV at 8A of current. This translates into typical power dissipation of 208mW, which is significantly lower than the 3.2W of conventional Schottky diodes. The SM74611 is also footprint and pin-compatible with conventional D2PAK Schottky diodes, making it a drop-in replacement in many applications.