These systems are easy and really inexpensive. Utilizing a “dead” car battery will cut the cost drastically. Many car batteries that cannot deliver enough amps to start a car can still be used to store power in a low current solar system. My 20 watt system has been running for years on a dead car battery. There are also applications for solar power that run only during daylight hours so no battery is needed.
Uses for Dead Car Batteries And Sealed Lead Acid Batteries