Solar power and rechargeable batteries

I'm looking at buying a thingy called PowerBank so that I will have the setup shown here , which is a 12w solar panel (already bought) , an Ansmann DigiCharger plus (already bought), and now the PowerBank to take a charge from the solar panel and to then pass it on to the charger. The reason for this is to stabilise the voltage/current as the DigiCharger cuts out easily and does not restart whenever the voltage varies by much. BUT, the PowerBank output is 5v and my camera batts are 7.4v. Can it do it? The shop tells me it can, that it's not really the voltage so much as the milli-amps, which are well matched at about 7-800mAh.

The shop also quotes a report from a happy hiker on his way through Scotland with pretty much the same setup who says:

"heres a quick test ( of the 12w solar panel), I'm blown away with this truly, gawd it
ridicules my old 6.5w! it saves me taking the battpak, hand winder, mini
invertor and also the old dbl20 batt charger now (i.e saving weight in
my rucksack).
So far it looks like 30 mins to charge 1000 mahs AAA's, 40 mins to
charge 2500 mahs AA and approx 50-60 minutes to charge my DBL20
camcorder batteries, what is nice about the Ansmanns is the audible
alarms, 10 seconds after insertion to say "yep I'm charging these
puppies" to a secondary one upon completion. This is way cool, as it can
be placed in the top of my rucksack, left and just hike, once their
charged I'll hear the alarm and know when to change OR plug in the
powerbank which runs my kypton at night and also doubles as a handy
phone charger.
I've ran some quick volt checks and all is cool, approx 15.14 volts
output at 600-800 mahs depending on sunlight. Avg so far 650 approx.
I can not envisage any problems with this when i'm away Unless it
hammers down for 18 days solid, which I doubt..I only need to recharge
my Camcorder batteries every 3 days as I have calculated 1 per day and 2
in reserve (i.e taking 5) - wow is basically all I can say....Oh roll on
Cape Wrath now...."

Another question, are rechargeable AAs and AAAs now as good as throwaways? I last recall that the ni-cads were not as strong but the mAh figures on the side of rechargeables I see nowadays look much higher. If so I could carry rechargeable AAs as well as camera batts and make the solar panel charge all sorts of things.

Any help most welcome. I'm also looking for an idiot's guide to physics or electricity as I forget the stuff I learned 30 years ago. Any leads on what book is best most appreciated as well.
thanks.

A good AA NiMH will last longer than an equivalent disposable - unless the disposable is a lithium based cell (like the Energizer Lithium range).

The only thing you need to beware of is the self discharge rate. Some cells go flat very quickly, even when they're not in use. Look for something like the Sanyo Eneloop range - the capacity isn't as high as some of the others, but they maintain charge well over long periods, whilst some of the cheap ones might go flat in a week.

A lot of electricity basics are covered on wikipedia - just type the terms into it ;)

Can you provide a link to the PowerBank? There seem to be a number of things by that name...

Try this link instead, for the 6.5w Sunlinq panel sold with the PowerBank: HERE I have the larger 12w panel, it seems to charge things twice as fast but Solar Equip tells me the PowerBank is for charging small things less than 3.5w in capacity.

thanks for the tip as to choosing good quality batts. I help a retired neighbour with all his IT stuff and he's forever choosing cheap bit he can buy at a street market, and wondering why his camera only gets 20 shots per charge!