Agree, those panels are very optimistically rated. I have 10 of them wired to a small grid-tie inverter, and while I don't know the efficiency of the inverter, I would assume that "150 Watts" worth of panels should be producing a bit more than 50-60 Watts in full sun...
On Tue, Jul 25, 2017 at 10:23 AM, Lee Hart via EV <ev@lists.evdl.org> wrote: > From: paul dove via EV <ev@lists.evdl.org> > >What is the wattage on that Lee. I calculate 3Watts. 0.25 X 12 V = 3 W > >Harbor freight sells a 15 watt panel. > >15 Watt Solar Panel > > I don't recall what wattage was claimed. But many of these panels will do > things like advertise the short-circuit current, and open-circuit voltage, > and multiply them together to get the claimed wattage. > > That's completely bogus. First, it assume perfect full sun, at the optimum > angle, and a low ambient temperature. Second, you can't even get half the > short-circuit current into a real load. Third, the voltage under load is > substantially less than the no-load voltage. > > The more honest vendors will provide a voltage, current, and wattage under > realistic conditions, driving an actual load. > > Even then, you have to consider how you will actually use the panel. In my > case, the PV panel sits horizontally, on the shelf under my car's back > window. Thus it is never at the optimum angle, the glass reduces the light > intensity, and the temperature inside the car is always hotter than ambient. > > -- > Excellence does not require perfection. -- Henry James > -- > Lee A. Hart http://www.sunrise-ev.com > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > Read EVAngel's EV News at http://evdl.org/evln/ > Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/ > group/NEDRA) > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20170823/5e4e2135/attachment.html> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
