View Full Version : How do you rate solar

09-09-2010, 09:02 PM
For all the electronics whizzes out there, how do you go about deciding what rating of solar electronic panel you need for tasks. I have been looking at solar chargers for AA batteries and or cellphones on trademe such as
this (http://www.trademe.co.nz/Browse/Listing.aspx?id=316179974)
this (http://www.trademe.co.nz/Browse/Listing.aspx?id=316168611)
this (http://www.trademe.co.nz/Browse/Listing.aspx?id=315865344)

but not knowing much about electronics I don't know if they are any good some constructive feedback is sought please.


09-09-2010, 10:46 PM
Taking your last example, I'd say that you may be frustrated trying to charge batteries purely using solar. Your typical AA NiMH has a capacity of 2000-2500mAh. If your charger actually puts out 100mA (as compared to my fast-ish mains-powered adapter that puts out 650mA), that basically means at least 25 hours to recharge, assuming bright (?) sunlight. That & the first unit look promising, as the 1st one has an internal battery & both of thos allow external charging via mains if you want to speed things up. The 2nd listing doesn't give much in the way of info, so I'd avoid it on that basis alone.

Having said all that, I haven't had any real-world experience with these things, so I can't say how they live up to their descriptions.

09-09-2010, 11:23 PM
I have also noticed there ain't much in the way of sunshine in caves or when it is raining for some reason. :devil

10-09-2010, 07:49 AM
Unfortunately your right there is no sunshine underground but then again Nelson is the sunshine capitol of NZ so it makes sense to make use of it when on other outdoor activities and in the summer I often am away for a week or so caving but based on the surface so some means of charging batteries would be ideal

10-09-2010, 12:51 PM
slow/trickle/'overnight' charging nimh is definitely NOT the way to go, you risk overcharging.
If the charge rate is to low, the peak detection (dV) doesnt work as well so the charger doesnt know when to stop.

Id imagine solar charger being so hopeless , overcharging nimh would never be an issue thou.

10-09-2010, 06:10 PM
To rate solar, assuming our Sun is 100 on the scale, other Suns will not even crack a 1 x 10^-6 for charging batteries. No matter what the Hitch Hikers Guide says, Betelgeuse is as much use for charging batteries as Nortons is for speeding up your computer.
This may change if you move from Nelson where even our Sun is a bit puny. If you go to Mercury, you will have plenty of zip from the panels.

I could not agree more with 1101, overnight charging is not the way to go with solar panels. ;)

11-09-2010, 08:39 AM
Solar panels of any size need a built in battery to store the power collected to be of much use.

P.S. We use 2 x 125W solar panels plus bank of 6 deep cycle batteries.