I'm new to electronics and I wanted to try powering my ATTiny85 with solar. I know solar power will fluxuate with the lighting (clouds, or in the shade), but I didn't want to use the solar to charge a battery and the battery power the ATTiny85.
If I were to add a capacitor between the solar panel and the ATTiny85 could that power the ATTiny85 for 5-10 seconds (assuming the right capacitor) while a cloud passes? If yes, is there an easy way to figure out the number of farads I would need for the capacitor?
You need to estimate the amount of charge that the capacitor needs to provide and divide that by the amount of voltage change that you are going to tolerate in order to calculate the required capacitance. If it is something that will simply switch on and off, the charge could be calculated from average current times duration. I suspect that in practice the solar supply won't actually switch on and off but will brown out under some conditions with the capacitor making up the shortfall - you need to decide what scenario you're going to support, and calculate the charge that the capacitor would need to supply in that scenario, and work out the required capacitance from there.
Yes I want the capacitor to make up the short fall during a brown out. I'm still not sure where to go from here? Should I test the solar panel I have and see how much it fluxuates during a day and calculate based on the lowest "brown out" I want to support?
you might want to go even a little further than the lowest brown out, try to think worst case sceenario