# Boost converter and solar cells

I have a solar cell with 0.5 V and 3.5 A output. Will a boost converter lower the current and raise the voltage? I would like to lower the current to max. 1 A and raise the voltage to max. 22 V.

A boost converter can't increase power. Your input power is 1.75 W maximum, so your output power will be less than that, maybe ~85% (due to conversion efficiency) so around 1.5 W.

That means at 22 V output your maximum available current will be about 68 mA. So no worries about having more than 1A available, but the load will dictate the current draw.

Note that it's very difficult to get a boost converter that will operate down to 0.5V input, so you might want to consider 2 or more cells in series.

Solar cells won't typically have set voltage and currents like you seem to have measured. Both measurements will vary with the load you are trying to draw, and amount of sunlight on the panel.

If you are charging batteries, then what you need is a maximum power point tracker (MPPT) that will find the right balance of current draw and voltage to pull the most power out of the panel possible.

It also sounds like you attempted to measure the properties of the panel while the output leads were shorted together - If you only draw 1A with your circuit, then the voltage will rise. How much it will rise is not something we can predict with the info you have given us, but a switch mode power supply that can do buck-boost will work to make your output a consistent voltage, assuming the sunlight is bright enough and the panel is appropriate for your draw.

• The maximum power point is usually found at half the open circuit output voltage and half the short circuit current. So for this cell it would be about 0.25 * 1.75 = 0.44 W. This is also where the source impedance equals the load impedance. Aug 22, 2022 at 19:28
• @PStechPaul is it really half? I thought more like 80% Aug 22, 2022 at 19:29
• @user253751 it would be half if the internal resistance of the solar cell was ohmic (linear). It is pretty well NOT ohmic, this is why MPP is where it is (at 70-85% of the open circuit voltage and 70-85% of the short current) Aug 22, 2022 at 19:48
• The MPP also depends on sunlight. The current increases with sunlight, but the voltage not so much. Aug 22, 2022 at 22:19