Hello,

Now let me explain why using a solar panel with multuple cells has advantages over a single cell.

Fisrt, as soon as your panel is rated for more than 0,5 volts when you buy it, you buy multiple cells connected in series. Voltage specified divided by 0,5 gives you the number of cells in parrallel panel has.

I rapidly did some drawings to explain more easily how it doesn't change the theory and why we benefit from multiple cells. Theory is : we MUST have cell operating to low voltage (0,1v) to have constant current and then current proportional to sun irradiance.

Fig. 1 shows 3 separate copies of a unique cell. I used the values from C. Wright. Each circuit has a short current 1.6 Amp, a 0,0625 resistance and the cell voltage is 0,1 volt. Voltage is low and require an opamp to higher the output level to have a good precision. These values being for 1 sun irradiance.

Now join the 3 circuits together like in fig 2. As you can see in the leg DE - CF and in the leg HI - JG we have 2 times 1,6 Amp in each leg, but one being the reverse of the other. So we have + 1,6 A and -1,6 A. In fact we can remove this leg as no current will go through it. They cancell each other. Same thing for HI and JG. Each cell has a voltage of 0,1 volt and current going through each cell is still 1,6 amp.

Now look at fig 3. We have 3 cells in parrallel, each one providing 0,1 volt and 1.6 A current going through. Now if you look voltage between B - C we have 0,3 volts. Like me, if you have a 5 volt panel, it has 10 cells in parraller (10 X 0,5 volts). To have each cell at 0,1 volts ( to keep the cell operating in constant current mode), we must have 10 X 0,1 volts = 1 volt.

As each cell in the panel should be really similar, we can expect good results with multiple cells. Having 1 volt swing voltage we do not need the opamp any more as it's job was to increase the 100 mv voltage.

J Guy

Now let me explain why using a solar panel with multuple cells has advantages over a single cell.

Fisrt, as soon as your panel is rated for more than 0,5 volts when you buy it, you buy multiple cells connected in series. Voltage specified divided by 0,5 gives you the number of cells in parrallel panel has.

I rapidly did some drawings to explain more easily how it doesn't change the theory and why we benefit from multiple cells. Theory is : we MUST have cell operating to low voltage (0,1v) to have constant current and then current proportional to sun irradiance.

Fig. 1 shows 3 separate copies of a unique cell. I used the values from C. Wright. Each circuit has a short current 1.6 Amp, a 0,0625 resistance and the cell voltage is 0,1 volt. Voltage is low and require an opamp to higher the output level to have a good precision. These values being for 1 sun irradiance.

Now join the 3 circuits together like in fig 2. As you can see in the leg DE - CF and in the leg HI - JG we have 2 times 1,6 Amp in each leg, but one being the reverse of the other. So we have + 1,6 A and -1,6 A. In fact we can remove this leg as no current will go through it. They cancell each other. Same thing for HI and JG. Each cell has a voltage of 0,1 volt and current going through each cell is still 1,6 amp.

Now look at fig 3. We have 3 cells in parrallel, each one providing 0,1 volt and 1.6 A current going through. Now if you look voltage between B - C we have 0,3 volts. Like me, if you have a 5 volt panel, it has 10 cells in parraller (10 X 0,5 volts). To have each cell at 0,1 volts ( to keep the cell operating in constant current mode), we must have 10 X 0,1 volts = 1 volt.

As each cell in the panel should be really similar, we can expect good results with multiple cells. Having 1 volt swing voltage we do not need the opamp any more as it's job was to increase the 100 mv voltage.

J Guy