Sorry Pericarp - that makes it worse for me
If the only benefit is that under USB conditions it charges as fast as an A/C Adapter then I really can't see the point to be honest - I'm not too sure how you would go to market with it when most people would probably say it's not something they have ever deemed to be a "problem"
If in people's eyes it is not a problem that needs solving, then usually that makes it 10 times harder to convince someone they need it.
I'm genuinely not trying to put you off - but I know how hard it is getting any charging device into retail/etail etc... and I can't see how someone like Maplins would ever want it unless it was a £1.99 product of which they were paying around £0.50p
You would only not need your A/C cable if you are somewhere with a computer (and therefore a USB port), and let's be fair the A/C cable for a phone is pretty small anyway - it's not like the block that comes with laptops etc...
The price of the Evo3000 is £39.99 - we have noticed there is an issue on 1 part of the site and are having it amended - however if you click to purchase it is £39.99
Obviously it depends which phone you have and the battery capacity as to how much charge it will give. An iPhone 4s will charge from empty to full around 2.2 times.
Obviously the point of having a solar panel is that it captures the light and charges the internal battery from it. How long that takes from UK sunlight really depends on how strong the light is - it's a bit like asking how long is a piece of string...
For example I leave one on the windowsill inside and it sits there charging away nicely, but can take a couple of days from empty to full if the sun is weak.
The other side to it is I have also been out in the garden with my iPad and it trickles enough power through to the iPad to keep it running all day - while still taking a charge from the sun into the battery
I guess what I am saying is that it is totally dependant on the conditions - wouldn't charge too well today from the sun