photovoltatic model simulation in proteus

[h1368]

hello
this is my first post in this forum.
I have designed an MPPT (maximum power point tracker) in proteus and need Photovoltatic model for test the circuit .
I know PV model consist of diode and current source but i pick those model from proteus's Library and the result of it is not correct for me
the I-V characteristic is like below picture

i found a diode model in proteus that i think , it can help me but don't know how set advanced properties .

 

[BradtheRad]

A PV panel can produce its maximum voltage at low current, or its maximum current at low voltage.

Its greatest watt output is at a middle point on the graph.

The best model I have been able to come up with is a voltage source and a resistor inline. If the panel is rated 12V, then I make the voltage source 19 to 22V (a realistic figure). I adjust the resistor value so that it will send the expected amount of amperes into a 12 V battery. If the panel is rated low W then I use a higher resistance. If the panel is rated high W then I use a lower resistance.

I believe this is sufficiently realistic, in the sense that (a) it has the ability to charge a battery bank (or capacitor) to the panel's maximum output voltage if left connected indefinitely, and (b) it has current limiting.

 

[h1368]

A PV panel can produce its maximum voltage at low current, or its maximum current at low voltage.

Its greatest watt output is at a middle point on the graph.

The best model I have been able to come up with is a voltage source and a resistor inline. If the panel is rated 12V, then I make the voltage source 19 to 22V (a realistic figure). I adjust the resistor value so that it will send the expected amount of amperes into a 12 V battery. If the panel is rated low W then I use a higher resistance. If the panel is rated high W then I use a lower resistance.

I believe this is sufficiently realistic, in the sense that (a) it has the ability to charge a battery bank (or capacitor) to the panel's maximum output voltage if left connected indefinitely, and (b) it has current limiting.

I used this model before but need a non-linear I-V characteristic like the figure im my last comment.
Because i am using ( Perturbation&Observation ) method for tracking maximum power point and the program that i wrote is just for non-linear I-V.
If i use a linear model like voltage source and resistor , the output W result is not maximum and it's wrong .

 

[BradtheRad]

Right, it's because the MPPT needs a model that behaves like a real PV panel.

To show what to aim for...

Here is real data I measured from PV cells. I hooked up various ohm loads and read the resulting volt level.
Then I devised a computer program to calculate amperes and watts, and plot all the data.

Four small cells wired in series:



Three graphs are superimposed: V, A, W.
The peak in the middle shows maximum power output (0.58 W) occurs with a 2 ohm load.

A 64W panel:



The maximum power plot looks as though it is missing its rounded peak. That tells me I should have tested it with loads between 5 and 10 ohms. Because I think I could have gotten 50W into an 8 ohm load.

The plots are crooked where I drew maximum amps. The connection may have been bad, etc.

The above data can give us something to shoot for, in simulating a PV panel.