the solar panel i am presenting here was patented by Nikola Tesla in 1901, and really only consits of a few parts, the panel, the capacitor and the switched load.
the idea came from an older copy of wikipedia's "Photoelectric effect" article (most images from wikipedia pages).

at this point its just an idea, so dont be critical as i havnt built it. but for those considering building, it should be constructable from household bits.

Step 1: Photoelectric Effect

The photoelectric effect occurs when short wavelength electromagnetic radiation (commonly known as visible light and UV light) strikes a surface causing elecrons to be emitted, making the surface positively charged.
according to the patent (i mean wikipedia reference), the surface struck is covered with an insulator (i would suggest black electrical tape) and is shiny or polished. it shouldnt be a perfect insulator, maybe megaohmic.

the metal beneath the insulator replenishes the lost electrons in the insulator and grows positively charged.

Step 2: Capacitors

as seen on the intro page, it has a capacitor, i would suggest the simple Leyden Jar as a good one, though i highly reccommend caution as these can store high voltages and i reccomend research before using one. if enough used it can be lethal. My tip would be to have a significant load on so it cant go so high or clearly mark High voltage and exercise caution.

they can be constructed by a layer of alum foil lining the inside and outside. a self charging one could be made with salt water on the inside (charged by shaking).

if you want to use electrolytics then remember the solar panel side is positive charged, the electrons are attracted from the earth connection to fill the negative side, i dont know if that would allow low volts/high current.

Step 3: Load

the patent suggests a motor but it shouldnt be limited to this however its recommended that something that uses high voltage is connected (low amps), the motor needs many turns of wire. you could try other loads of course. because of the low amps try to minimise the contact to the positive pole of cap (panel supports etc) else it will discharge through your supports.

supporting the plate on top of the jar could be ideal, as shown, or you can be adventurous and design more compact designs. like another insulator under the top plate (no light to go on that one) with another plate under that for the capacitor. possible water cooling but that could hinder electron emission as the old valves needed a heater to emit the electrons.

i hope you enjoyed it, as i said its an idea, perhaps the cheapest solar panel with the most output that you can get.