I have always been interested in alternative power, and my interests have particularly focussed on solar power. Over the last few years I have managed to get my solar power setup working pretty efficiently and have managed to move a lot of my small power requirements off the grid. I would love to move everything off the grid, but that is just not realistic in a normal rental apartment in Tokyo.
With my current setup I find that I can charge most of my small devices using solar energy. I am currently charging my iPhone, GoPro 2, Eneloop batteries (used in various things), Knog Blinder Road 3 and Blinder Rear lights, Garmin 800, and my DSLR batteries. I do occasionally charge my iPad as well but it really draws too much power to be able to charge it entirely off solar while charging my phone everyday.
So, as you can see, I am by no means off the grid but a lot of my convenience devices, all of my electronic bike gear and my cameras are charged with solar. As for emergency use, assuming a moderate number of sunny days I would be able to keep enough lights, a radio, iPhones and other little bits running pretty much indefinitely. Along side a gas stove, a good supply of water, sufficient food and emergency toilet supplies I would be reasonably comfortable in the short term as long as I could stay at or near my apartment.
What is my setup? Well, I am running 3 portable solar panels (2 Goal Zero Nomad 7s and a Nomad 13) in series for a theoretical total of 27 watts. I really expect no where near that output in anything but ideal conditions. I have a Goal Zero Yeti 150 solar generator, which has slightly upwards of 150Wh of power storage and a supplementary 10.4Ah Li-ion battery pack with 2 USB outputs. All together it has cost me about $450 over the last few years for the hardware. I find that using the sun to trickle charge the Yeti 150 and then using it to charge the Li-ion battery pack works pretty well. That way I can top off my Yeti 150 regularly with good run of sunny days while using the Li-ion battery pack for my daily iPhone and small device charging needs. I very rarely lose any solar power that my panels are pulling in through this setup. The only time I would lose any potential power is if I were to go on a vacation of some kind and be away from home for 5 days or so. Even then I would come home to nice full batteries!
As for the charging time for the system, it seems to take anywhere between 12-30 hours to charge the Yeti 150. I am generally using the panels behind glass in my room which really cuts down on efficiency. Luckily, the windows in typical apartments here in Japan are thin, single-pane and do not appear to have any UV or other coatings. My apartment bedroom window is facing 165°S so the panels can get direct sun exposure from sunrise until around 11am or so. I do find that even on cloudy days my panels pull some charge but really not enough to do much more than charge 2 AA batteries in a morning.
I do hope to have a proper solar system in place one day, but for now I will just make the best of what I’ve got 😉