Ralph Oborn said:
> How close do you have to match the voltage and current?
Very. The things you listed will probably take +/- 5% on voltage but
the same total power will be required. Powering a laptop requires
either a big panel or a working battery in the laptop, plus the supply
requirement is a worst case one for the most part. My laptop power
supply is rated at 4.5A but rarely draws more than 3. Not that that is
much relief, it's still 50W. But in practice if it's shut down it will
charge quite happily at about 1A so the 20W panel is adequate.
ja "dotty" hackett is at best ill-informed. If you buy cheap junk it
will not work, leaving you out of pocket the "cheap" price and still
wanting to fulfill the original requirement. Especially with solar
gear, the iron law of engineering holds very true - light, cheap,
reliable: pick any two.
If cheap is the main criteria buy naked amorphous panels and wire them
into a home-built housing, then get a cheap solar regulator and an old
car battery (often available free, but very low joules/kg rating at
that point), then find 12V supplies for all your stuff. A setup like
that could be almost free if you're good at scrounging, especially if
you can find some discarded solar toys (ideally a 12V car battery
top-up charger (these are fairly common in Australia)).
For lightweight, a 1kg li-ion battery fed by a flexible panel via a
supercap and smart charger, powering the laptop directly and the other
stuff via custom-built smart regulators would be very light (but
around $1000 in parts alone, you'd need to arrange access to a surface
mount fab yourself).
The compromise I used works for me and was a balance between
affordable and what I was willing to carry.