>> I can't convince myself that it isn't rubbish because their basic
>> premise is wrong.


                 http://focus.ti.com/lit/an/slua394/slua394.pdf

> The bq24030 appears to be a linear charge controller. =A0Their scheme
> concentrates on obtaining maximum power output FROM the solar panel
> (which it may well do) but the whole point is to deliver maximum power
> INTO the load which isn't going to happen when your controlling elements
> are simply burning off power in order to perform the matching between
> source and load.

Yes - that was my point - they seem to have built their app note
around the idea that you want the panel to be at the maximum power
point, not realising that a PV panel invariably makes MORE current at
voltages below this point, so that if the battery loads the panel
below Vmpp it will provide MORE battery charge than if held at Vmpp.

ie they have replaced a Schottky diode with an expensive IC that
provides less charge than the diode alone would.

Going in the other direction, if Vmpp is below the battery voltage
then the panel is mismatched and will again provide less than maximum
charge. In that case more panel cells in the same area are  required
OR a boost converter.

If a panel is reasonably well matched to a battery (more usual in
smaller than large) then an MPPT controller has to be quite efficint
to be of any great value.


       Russell

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