Wow you do tend to overcomplicate matters! :o)

Let's try it the easy way. The GOAL is to get the
maximum energy out of the solar panel, and into the
battery system.

Now the purpose of the PIC PWM is to present a
variable load impedance to the solar cell. You did
understand this? That the PIC can adjust the *DC
current* drawn from the solar panel?

In a real world renewable energy system the energy
produced for use is easily given by the *current
into the battery* as NO MATTER what the battery
voltage is at any point in time the MAX performing
solar setup is the one that is putting the MAX
current into said battery at all times. Input and
output power become relatively useless terms, the
system needs to put the MAX CURRENT into the battery
for all available levels of insolation.

Which is why my proposed PIC MPPT design simply
dispenses with calculating or measuring power and
instead focuses on the one desired objective of
*putting max current into the battery* at all times.

To this end it only needs to measure current into
the battery as it's one sensor, and adjust the DC
current drawn from the panel up and down until the
MAX OUTPUT current is found.

It's assumed in any design that we use fast switching
times and suitable PWM speeds and inductor types etc,
so the efficiency of the buck or boost switcher is
basically as good as it gets. Nothing to measure.
An engineer's job is to find the simplest and best
solutions, not to argue semantics.
-Roman


Peter L. Peres wrote:
> *>Why??? This is not necessary at all. The only objective
> *>is to put the max current into the battery at all times

> Because the maximum efficiency power transfer equation requires that the
> charger present an impedance equal to the Ri to the panel at all times and
> at the same time the charger present an output resistance equal to the Ri
> of the battery at all times. A MPPT controller works as a self-tuning
> 'impedance matcher'. It can be shown that all attempts to do it otherwise
> involve using the perpetuum mobile principle if they are to achieve higher
> efficiency than the maximum efficiency power transfer equation predicts.
> For this it has to know Ri of the generator and load at all times.
>
> The m.e.p.t. equation simply says Zgenerator = Zload for maximum power
> transfer. There are no shortcuts around it. It is the same equation that
> governs transmission line and antenna matching.

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