Dummy inventor needs help

Hi There
I have filed for a patent on my idea / invention. It is a solar powered consumer electronics device; approximately the size of a digital camera. I have identified 3 potential designers through to suppliers (all in China); they can each take rough drafts and design, tool up and produce.

I have decided to offer a really basic unit for as little $ as possible, plus an enhanced version. Actually, I want it to be the same unit available with or without extra components / functionality, so as to keep my costs down and perhaps allow an upgrade path for basic unit customers.

OK, I need to make a decision regarding the basic design, whether to incorporate all the electronic components into one casing / unit being driven by one solar panel, or should I put the components into two interlinked units and thus be fed by two solar panels.

Each unit could / would have a double / two AA size rechargeable battery unit for when the clouds come out / night falls. Of course these can be charged from an external power source as well as from the solar panels. Or, without any batteries fitted, the solar panels would directly supply the unit.

So my questions are;
1) How realistic would it be for me to have all the electronic components in one unit being fed by a single solar panel..
2) With no sunlight, how long would the batteries would last a) if there were 2 AA batteries or b) 4 of them.

Can you help this electronics dummy out ?

Let me tell you what I have.

1) A single solar panel uses a 0.7W cell and produces 5.5v 800ma
2) Electronics component "A" uses 5v 100mA
3) Electronics component "B" uses 5v <80mA
4) Electronics component "C" uses 12v 90 mA
5) An AA battery is 1.2v 2100 mAh
Of course, there will be electrical resistance from the board, etc.

Any / all help / guidance appreciated.
Cheers
Mark

assuming an efficiency of 80% your total power need would be

A => 0.5W/0.8 = 0.625W m
B => 0.4W/0.8 = 0.5W
C => 1.08W/0.8 = 1.35W

Also the power of the solar panel is for theaximum daylight. de-rate it by 70% to account for average light flux through out the day.
also battery will loose 5 to 10% charge during storage as they grow old.
hock

Hi Hock
Thank you very much for replying.
So the solar panel calculation to W is 5.5v x (800mA ÷ 100) = 44 W, is that right?
So the solar panel is able to support 44 W x 70% = 30.8 W, is that correct?

I am confused as the specification of the panel is 0.7 W, what am I missing here? :roll:

Finally, how do I calculate how long the batteries will last? Presuming they are new, fully charged and driving all three components?
Please help
Mark

the power consumption of the circuit is 0.625W+0.5W+1.35W = 2.475W
if it needs to run for 10 hours a day then the rating of the battery is 2.475*10 = 24.75WHr
Divide it by batt voltage of 1.2V you get Capacity in MaHr 20.625Ahr.
Take a 80% safety margin you get 25.78AHr.
so you will need 25.78Ahr/2100mAhr =~ 12Batteries.

one better choice would be to use cell phone batteries, which are avalable in 3.7V and up to 5000mAHr, and are very cheap.
you can do the calculation for them on similar lines.

hock