Set it in the sun for one hour when completely dead and I got over two hours of light on the reading mode( which is the second highest level (approx 40-50 lumens) )
- They have a boost mode at 120 lumens, a 100% 60 lumen mode, and a 50% mode which they call the reading mode and that one is 30 lumens, not 40-50. My figures come directly from their website, not sure where yours come from? You wrote about 100% output for 2 hours after 1 hour in the sun. Are you now saying it does not run at the 100% level but the 50% level?
Then the panel is indeed a sunpower PV cell and the lines are what they call a bus line to mend the break of the pn junction.
-IT ABSOLUTELY IS NOT A SUNPOWER CELL. Grid lines do not mend breaks! They are to carry charge to busbars which would be the main contacts. SUNPOWER has NEVER made cells with gridlines on the front of the cell. I don't think they have even made a cell in the last many years only 18% efficient. That said, WakaWaka does not even claim that this is a SUNPOWER cell. They DO claim their new unreleased USB version has a SUNPOWER cell and the picture would indicate that is the case. No need for the solar primer .... I have been involved in cell production equipment.
You are right as perpetual motion does not exist but we are able to get to the point of only losing 30% and this is due to heat loss, reflection and impurities/properties in the silicon itself. Alternative energy is improving on the point of diminishing returns and in no way can solve it.
- Not sure what your point is here. A 0.75 watt cell is a 0.75 watt cell (at 25C, AM1.5, 1 SUN). Heated up, with electronics losses, battery losses, etc. it behaves effectively like a 0.5 watt cell. Your statement above is pretty meaningless w.r.t. this. Similarly a 0.5watt driven LED is a 0.5watt driven LED, but there will always be losses in driving it. 1 hour from a 0.5 watt effective cell will never run a 0.5 watt driven LED for two hours. Talking about 30% loss due to heat, etc. does not change energy in = energy out.
- Again, what is the point of this comment? We have long ways to go on solar panels. Sure single junction silicon technology will top out at 28% or so and with cells hitting 23-24% we are a good point of the way there, but that is why companies are working on multi-junction cells based on silicon technology to push that limit up to at least 35% and other methods are being explored to push that up to the 40 range. That is without triple junction gallium arsenide technology which is brutally expensive and requires concentration to achieve maximum efficiency.
I think you and lynx can stay under the bridge with trolling as its not needed ANYWHERE. As this is the last time I comment on childish behavior, I would appreciate it if you and lynx keep the smart @$$ remarks to ones self.
- I am sorry, but if you are going to post a review and claim expertise which others are going to base a purchasing decision on, then be prepared to back that up when the claims of your review and/or the product do not stand up to simple engineering and math review. That is not trolling, that is consumer protection. Your "review" was not critical, it was more of an advertisement.
- As I have said, I am not doubting that the product "works", only that the claims made are not possible. Those claims, which I have disputed with THEIR OWN SPECIFICATIONS ARE:
* 60 lumens (0.5 watts by their literature) for 2 hours with a 0.75 watt cell : Not possible as cell/electronics and battery losses make this not possible (see above)
* 60 lumens (0.5 watts) for 8 hours or 4 watt hours from a battery that is less than 3 watt hours
These are the manufacturer's claims which you stated are absolutely true.
You can call me and Lynx childish or trolls or whatever you want BUT --- Here is an idea .... Address the issues! Yes, address the issues.
- Show us the math that shows how a 0.75watt cell with charging and battery losses powers 0.5 watts for 2 hours after only 1 hour of charging
- Show us the math that shows how a <3 watt hour battery pack can drive 0.5 watts into an LED for 8 hours (4 watt hours). Please note the supplied graph shows 100% power for those 8 hours.
- Show any Sunpower cell literature that shows front gridlines (I think you confused their existing and new product here)
- Address the run time graph. Did you create it? I thought the WakaWaka2 was not released yet?? That would mean this graph was from WakaWaka would it not?
Semiman