No particular item in mind to power, just a fun alternative source of energy (9V are pricey as Hell lol). I was thinking charging a battery source might be best but im unsure what type of battery i should look into for this. Rechargeable ones sound like what i would need. Don't know much about capacitors but those sound more like on the fly quick storage than long term solutions like this.
Solar Cell Array ---> Rechargeable Batteries ---> Whatever voltage level regulator --->Power stuff