I'm designing circuit based on a microcontroller, powered by a solar cell. As an experiment, I wanted to add an energy harvesting IC (bq25504). When programming, I'd like to be able to charge the battery through the USB port as well.

I thought of also feeding the current from this port to the input of the harvester.

But the problem is: I can't use a diode in series with the solar cell. The energy harvesting IC is so efficient it can harvest energy from voltages as low as 80mV, so if I add a series diode I'd be losing that ability.

What would happen if I put the V of the programming port in parallel with the solar cell? Will the solar cell get damaged because of reverse-biasing?

  • \$\begingroup\$ -5V is safe , -6 is not \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Apr 18 '18 at 13:17
  • \$\begingroup\$ @TonyStewartEEsince1975 is it the same for all panels? There are single-cell ones rated for 0.5V OC, can I put -3.3V across them? \$\endgroup\$ – hjf Apr 18 '18 at 14:12
  • \$\begingroup\$ show me the datasheet \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Apr 18 '18 at 15:34
  • \$\begingroup\$ @TonyStewartEEsince1975 well, it's a Shenzhen Special so there's not really much info. Guess I'll have to test them myself. \$\endgroup\$ – hjf Apr 18 '18 at 17:20

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