Unless one is focused on increasing landfill, or way-the-hell out in the boonies and so off the grid, or the locations are very far from any source of mains power (such as in orbit), I can see no reason for solar-powered (or even wind powered) lights. These devices are very popular in our neighborhood, everything from the little stick-in-the-ground lights to the devices similar to what was linked. However, I have _NEVER_ seen one of these devices last more than a year, mostly only a few months. Cheap cells, cheap batteries, cheap electronics, cheap housings and normal mid-Atlantic weather chews them up and spits them out. If one must have low-voltage, go for a transformer-served system - our next-door neighbor has such a system that has been in place now for over 6 years without a failure. Otherwise, take the trouble and install a mains-powered system. Some other observations:
a) Exterior lights - most especially those on motion-sensors - will not protect one from criminals. First, most of them operate by daylight - complete with uniforms, marked trucks and clip-boards - know that you are not at home, and know exactly what they are doing. They will be in and out in less than 10 minutes mostly 5 minutes or less.
b) And should you have that unique night-time burglar, all you are doing is giving them light to work - remember, they KNOW that you are not home already.
c) Overall in the United States, only 14% of all burglaries are home invasions - that is the breaking in to an occupied house. Of those the majority are seeking confrontation, usually related to drugs, and they usually know their victims. However, those home-invasions tend to be incredibly violent, and seldom motivated by simple greed.
d) The average police response time in the US by location is over five full minutes from the time called. So, an alarm system notifies a security company, which in turn attempts to reach the owner, and then only dispatches the police.

So, ask yourself:
a) All sorts of lights at a cost and of dubious utility?
b) A loud, but well-trained dog? Size does not matter.
c) A shotgun with some basic training in its use, and a strong dose of common sense so that someone dropping in on a surprise visit is not damaged?
d) A burglar alarm system - knowing that the most useful part of it is the sign outside? Aside: Alarm systems that are tied to smoke and heat detectors do have a function in the protection of real-estate. Otherwise, not really, again other than the sign.

Hand guns are long guns are neither legitimate nor very useful for home defense other than perhaps as a club.

Peter Wieck
Melrose Park, PA