First of all the panels you buy (most likely online) should have a peak voltage output of about 18V. This will keep the panels from producing (during mid day) some voltage below the 14.6 or so Volts that the panels will need to push in order to put anything into the lead acid batteries.
Secondly, you want to consider how much storage you will buy. I'd recommend a 12Ah 12V battery as a minimum ($25) because that will be enough to push a LED outdoor flood light for 4 hours. So if you were inside during a power outage and wanted enough light to eat a meal in a pretty large room and have 4 hours to do so, a battery this size would do. If you go with a 26Ah battery ($49) at the same voltage, of course that same light would last all night.
Lastly, there's the charge controller. It's hardly worth mentioning on this system because they are so cheap and safe to use with lead acid batteries. The only thing worth considering is scale. You can get a 10A draw and charge rate controller for $10. The panels I'm listing have a 4.2W max power output at 18V. So you'd have to hook up about 45 of these panels in parallel before you blew the controller with your panels. For this build, I only have 2 in parallel for a total of .47 Amps of power at any given time.
So what I'm saying with this last point is you have plenty of room to scale this system with an entry level charge controller. You can add more panels and/or more batteries to this system, and the same charge controller will be appropriate.
On a rant-like note... scale is what makes this entry level system so attractive. You might be saying, why don't I just buy a solar flood light with batteries already installed and bundled? The answer is, for all the small PV systems you can buy, they are limited to a pretty specific use-case such as a walkway light, or a radio, or a USB cell phone charging system. The room to use the juice from these cheaper systems for other applications is more limited than what I'm listing here. Here's the bill of materials with pictures. Everything can be purchased on Ebay or Amazon.
1. 12 Volt, 12 Amp Hour SLA battery.... $24
2. 4.2 Watt, 18 Volt solar panel (x2)....... $17
3. 10 Amp, 12V solar charge controller.. $8
*all these screen shots are for reference only and there's no guarantee these sellers are honest.
I've built this myself with the items listed here (just form other sellers) and I'm using it to charge my electric bike batteries. So I'll have more to say on performance of the system later, but you will have your own use for this system such as lighting or heaters or water pumps. The only other thing to make this almost universally usable is a 12V AC inverter so you can run computers, TVs and appliances. You can purchase a 2000 Watt AC inverter for around $40 (but I would add more batteries in parallel before attempting to pull 2000 Watts... and use appropriate wiring as wires can get hot).
