Energy harvesting: micro power measurement

[Tweepy]

I'm designing a hand-held system with 4 solar panels on every side of the case.
As the sun exposure is not constant, and handling the device interfere, I would like to know the typical energy available during a full day of use.

What's the best approach among:

• 2 cheap PC multimeter, one with a good uA range, like the UNI-T UT 61E
• 2 cheap PC multimeter plus a uCurrent

I'm looking for a sub 200$ solution, ideally running Sigrok or at least linux to run it with a laptop in my backpack logging U and I in a spreadsheet.
The voltage is from 1 to 8 volts, current from 1uA to 30mA.
This bench will be also used for evaluating the power drained by the system (MP430, sleeping at 50Hz, from 1uA to 5mA @ 3.3V)

Is recording U and I from different device (not sync) a problem?

I'm looking for any hint in this setup, but also recommendation for 2 nice multimeter reference fitting the bill (and my budget). (I dont like 9V battery, I would prefer 2xAA and USB of course is nicer than RS232 to avoid converter)

[taemun]

(This might be better suited to the Projects, Designs, and Technical Stuff forum, not sure.)

Four solar panels, one each side? Are you planning on putting those in serial or parallel? Either way, you'll probably be doing more harm than good:
http://en.wikipedia.org/wiki/Photovoltaic_system#Shading_and_dirt

You may be able to get away with summing diodes.

[Tweepy]

(This might be better suited to the Projects, Designs, and Technical Stuff forum, not sure.)

Yes, maybe, but it's more about measurement than project design itself

Four solar panels, one each side? Are you planning on putting those in serial or parallel? Either way, you'll probably be doing more harm than good:

Of course, there will be bypass schottky diode on each solar panel. The device has many mounting possibilities and cannot rely on one panel.

[Marco]

The voltage is from 1 to 8 volts, current from 1uA to 30mA.

Why would the voltage vary? Won't you use it to charge a battery or something at fixed voltage?

[Tweepy]

Why would the voltage vary? Won't you use it to charge a battery or something at fixed voltage?

Simple answer: http://en.wikipedia.org/wiki/Maximum_power_point_tracking

[Tweepy]

I think the UNI UT61E is fine for this job: 20kcounts, 2 values per sec, and run USB/HID on Linux :
http://translate.googleusercontent.com/translate_c?depth=1&hl=en&ie=UTF8&prev=_t&rurl=translate.google.com&sl=auto&tl=en&u=http://diyftw.de/wiki/doku.php%3Fid%3Dprojekte:ut61e&usg=ALkJrhho3tD4oG25B4KTU-jEOLJxMVXiBg#links