only bit thats the issue is Bigger = better
bigger Mah (milli amp hour) battery = better (more run time)
bigger wattage solar panel = better (faster charging of battery)
bigger lumin light out put = brighter aka better
So most people will now be familiar with USB plugs on computers/ car stereos phone chargers the standard size usb is called USB - A and the standard micro usb as most phone chargers (unless your on apple use)
thats the only bit of technical stuff you need to know
so on to the bits

can of coke to give idea of size.....
so a USB solar charger plenty on the market
type "Solar USB charger" into ebay or amazon and loads come up
http://www.ebay.co.uk/sch/i.html?_from= ... r&_sacat=0
higher the wattage the faster it will charge your battery bank.....
this is mine i got last night in Lidl for £30:

http://www.lidl.co.uk/en/our-offers-249 ... 3695&ar=10
again ebay or amazon" USB battery bank "
http://www.ebay.co.uk/sch/i.html?_odkw= ... k&_sacat=0
again heres mine £7.99 from lidl last night

http://www.lidl.co.uk/en/our-offers-249 ... 3667&ar=10
according to the blurb the 5200mah battery Can fully recharge an iPhone 5s up to 3 times or a Galaxy S5 up to 1.8 times
so its rather powerful again you can get bigger ones in terms of capacity
so plug the usb charging lead into the socket on the charger and into the charge plug on the power bank place outside in the sun and it charges up....

(you can also use a usb mains charger or car charger to charge the battery up)
so now we have a nice fully charged battery after a day of it sat in the sun / cloud (just beware its not water proof)
so you can now charge you phone /tablet and any other usb chargeable device

but its got dark.... now some bright spark has made a USB powered light bulb.. which are about £2 on amazon...
https://www.amazon.co.uk/Well-Goal-Camp ... light+bulb

they draw about 1a for the techy people reading this and give about 40w light
so then cobble them to a usb A type extension cable £1.50 for a 5m one i paid on ebay
and you can run 3 off my battery at one time if you wish:
heres 2

i just need to work out the run time now and charge time for the average uk conditions
total cost about £45 all in