0
\$\begingroup\$

I am designing an energy harvesting system that runs off of a couple of solar cells. Each cell is a Dye-sensitised solar cell and gives out around 0.5v. Because of the placement of the cells around the casing, the different panels might be under slightly different lighting. What would be the optimal strategy to combine these panels? Is there some balancing circuit that I can use?

Edit: adding more details

Right now I am planning to use 3 cells, arranged roughly as shown. enter image description here

Each panel is roughly 2cm x 8cm

\$\endgroup\$
2
  • \$\begingroup\$ This would be easier to answer usefully with a ballpark number instead of a couple - 3? 13?. Does placement […] around the casing mean for every cell, there will be one facing in opposite direction ("cylinder")? Angle difference about 30° (flat cone)? Lighting/insolation? Voltage level of consumer/storage? \$\endgroup\$
    – greybeard
    Jan 3 at 9:30
  • \$\begingroup\$ @greybeard I've updated the question \$\endgroup\$
    – raider0ne
    Jan 3 at 14:15

2 Answers 2

0
\$\begingroup\$

Just connect the panels in parallel and you'll be fine

\$\endgroup\$
3
  • \$\begingroup\$ Are you sure about this? From what I've read, just connecting things in parallel won't be optimal \$\endgroup\$
    – raider0ne
    Jan 2 at 16:21
  • \$\begingroup\$ Please expand why this answer needs to be better \$\endgroup\$
    – Voltage Spike
    Jan 2 at 18:52
  • \$\begingroup\$ If unequal (on the basis of light exposure here) panels are connected in parallel, the output current will not simply add up. The under-performing panel might act as a sink and reduce current or voltage \$\endgroup\$
    – raider0ne
    Jan 3 at 5:30
0
\$\begingroup\$

You're going to want to put them in series. If you put them in parallel, you can at best only get 0.5V from the system. That low voltage is going to be hard to work with for any downstream convertor. The total voltage will be the sum of each cell voltage at any given time. Typically, you would put a bypass diode (reverse biased) across each cell to pass the current due to source imbalance. But at 0.5V open-circuit voltage, you would have to use Schottky diodes (0.3Vd) to be effective. The downside is they have higher reverse leakage current which may or may not be tolerated in you energy harvesting application.

\$\endgroup\$
6
  • \$\begingroup\$ Will the current output be severely impacted if one panel is shaded in the parallel configuration? Will the shaded panel act as a sink? \$\endgroup\$
    – raider0ne
    Jan 3 at 18:42
  • \$\begingroup\$ @raider0ne The output will not be severely affected by the shaded cells acting a sink. There will be some (negligible) leakage current do to diffusion across the PN junction. This is intrinsic of all semi-conductors. \$\endgroup\$
    – MOSFET
    Jan 3 at 19:14
  • \$\begingroup\$ No PN junctions here, As I've mentioned, the panel is DSSC type so I'm afraid the it is quite different compared to regular Si panels. And one of my main concerns is possibility of damage to the cells due to reverse flow of current \$\endgroup\$
    – raider0ne
    Jan 4 at 6:38
  • \$\begingroup\$ If the cells are connected in series, I don't see how there could be a reversal of current under normal operation. Unless you are worried about the load/storage mechanism back-feeding the panels? Even if that's the case, just use a diode to block a potential fail mode of the controller. \$\endgroup\$
    – MOSFET
    Jan 4 at 8:25
  • \$\begingroup\$ I was talking about the parallel configuration there..... So if the cells are connected in series and one cell is shaded, the shaded panel will be safe as long as the bypass diodes are present... right? \$\endgroup\$
    – raider0ne
    Jan 4 at 12:23

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.