Isofoton -150/24 photovoltaic panel

[mah]

I have Isofoton -150/24(Vmax=34.6,Imax=4.35,Voc=43.2,Isc=4.7 at STD) photovoltaic panel and i need to do a model for it but i don't understand what was written about current and voltage temperature coefficients (Ki,Kv) it is written in datasheet Ki=.042%/c and Kv=-.323%/c what is that mean ?
if any one have the datasheet please attach it cause the one i have is for current source array (Imax=8.7 A, Vmax=17.3).

another question

could i use lm35 to measure surface temperature of photovoltaic solar cell ? or should i use temperature sensor specially for that purpose ?
thanks

[inetdog]

I have Isofoton -150/24(Vmax=34.6,Imax=4.35,Voc=43.2,Isc=4.7 at STD) photovoltaic panel and i need to do a model for it but i don't understand what was written about current and voltage temperature coefficients (Ki,Kv) it is written in datasheet Ki=.042%/c and Kv=-.323%/c what is that mean ?
if any one have the datasheet please attach it cause the one i have is for current source array (Imax=8.7 A, Vmax=17.3).

another question

could i use lm35 to measure surface temperature of photovoltaic solar cell ? or should i use temperature sensor specially for that purpose ?
thanks

The Ki tells you how much the current increases as the temperature of the panel rises. It is, as the units indicate, the percentage amount by which the current increases for each degree Celsius. Probably using 25C as the base, since that is the temperature for STC measurements.
The Kv tells how much the voltage decreases (since it is a negative number) as temperature increases. The result, since Kv is much greater than Ki, is that the output power decreases with temperature.
The other important effect is that the open circuit voltage, Voc, can be much larger when the panels are cold and this can affect how many panels you can safely put in series into the input of a CC or inverter.

The same temperature coefficients apply equally well to all of the voltage or current parameters. That is both Imp and Isc and both Vmp and Voc.
Just try to make sure that you are measuring the temperature of the cells rather than either the surface temp of the glass or the reflected IR temperature of the sky or whatever the panel is facing. Measuring the temperature of the back of the panel may give a better reading than the front glass.

[mah]

Okaaaaaaaaaaaaaay , what are the values of Ki and Kv for this panel. i need to use it in simulink by matlab so i need numbers.

[inetdog]

Okaaaaaaaaaaaaaay , what are the values of Ki and Kv for this panel. i need to use it in simulink by matlab so i need numbers.

I though from you post that you had the data sheet:

it is written in datasheet Ki=.042%/c and Kv=-.323%/c what is that mean ?

The values depend almost entirely on the nature of the cell chemistry (i.e monocrystaline, polycrystaline or amourphous or non-silicon entirely) and not on the way the panel is assembled.
So you would get a good approximation from any similar cell type panel.
If your panel is mono-crystaline, the following data should be close enough for your needs: http://www.enfsolar.com/pv/panel-dat...ystalline/1612

[mah]

I had a similar datasheet not its one. i still don't understand what is % after the number mean ?

[inetdog]

I had a similar datasheet not its one. i still don't understand what is % after the number mean ?

% is the symbol for "percent" in most countries.
So 1% = .01. and .01% = .0001 as raw numbers.

[mah]

% is the symbol for "percent" in most countries.
So 1% = .01. and .01% = .0001 as raw numbers.

in any country any children will know that , i mean will i write Ki=.042 divided by 100 (%) , i think no body here mention that in datasheet

[inetdog]

in any country any children will know that , i mean will i write Ki=.042 divided by 100 (%) , i think no body here mention that in datasheet

Some people just make the assumption when writing documentation that 1% is good enough and that writing 1/100 (%) is less clear rather than more clear, since 1/100% would be different from 1/100 (%).

Similarly, I would expect the notation used in the data sheet to show some symbol for Celsius degrees rather than just "c", which could be misunderstood as "100".
Example: -0.334 %/°C.
(This is actually technically incorrect too, since the divisor is an offset of so many Celsius degrees (C°) from a reference temperature rather than an absolute temperature in degrees Celsius (°C)

When you already know what the value is supposed to represent, it is easier to work around incorrect representations.

[mah]

any body help me please and give me a direct answer.

[inetdog]

any body help me please and give me a direct answer.

Temperature coefficient of Imp is approximately the same as temperature coefficient of Isc, which is 0.048 %/°C
So Ki = .00048.

Temperature coefficient of Vmp is approximately the same as the temperature coefficient of Voc which is -0.334 %/°C.
So Kv = -.00334. The minus sign is important!

[SunEagle]

I believe the OP has the data sheet for a 150watt panel with a Vmax=17.3 and Imax=8.7.

Now he wants the Ki,Kv temperature data for an Isofoton 150 watt panel with a Vmax=34.6 and Imax=4.35.

[mah]

I believe the OP has the data sheet for a 150watt panel with a Vmax=17.3 and Imax=8.7.

Now he wants the Ki,Kv temperature data for an Isofoton 150 watt panel with a Vmax=34.6 and Imax=4.35.

exactly I have looked in all datasheets on their site for all modules they have the same Ki and Kv so i will postulate that my panel is similar.but the problem here is that the written number in datasheet can't be divided by 100 because it will be very small coefficient , i tried it in simulation it gave almost identical curves for different temperature and that isn't true.
i hope somebody get me and give a hand.

[SunEagle]

exactly I have looked in all datasheets on their site for all modules they have the same Ki and Kv so i will postulate that my panel is similar.but the problem here is that the written number in datasheet can't be divided by 100 because it will be very small coefficient , i tried it in simulation it gave almost identical curves for different temperature and that isn't true.
i hope somebody get me and give a hand.

The value for Kv = -.323%/c is the amount of voltage loss for every degree Centigrade above a specific temperature. The -.323% is not divided by 100.

According to a specification sheet I found for the Isofoton ISF-150, The Voc = 22.6v at 25 C. There is a chart showing that the Voc = 20.0v at 55 C. So the panel loses 2.6 volts for a 30 degree Centigrade increase.

[mah]

The value for Kv = -.323%/c is the amount of voltage loss for every degree Centigrade above a specific temperature. The -.323% is not divided by 100.

According to a specification sheet I found for the Isofoton ISF-150, The Voc = 22.6v at 25 C. There is a chart showing that the Voc = 20.0v at 55 C. So the panel loses 2.6 volts for a 30 degree Centigrade increase.

okay you knew the loss from the curve , i want to calculate it depending on Kv so give me a value for Kv i don't know what is .323% mean how to use it in m file matlab?

[inetdog]

The value for Kv = -.323%/c is the amount of voltage loss for every degree Centigrade above a specific temperature. The -.323% is not divided by 100.

According to a specification sheet I found for the Isofoton ISF-150, The Voc = 22.6v at 25 C. There is a chart showing that the Voc = 20.0v at 55 C. So the panel loses 2.6 volts for a 30 degree Centigrade increase.

.323% would be .00323. Multiply that by 30 and get .0969. Multiply that by 22.6 and get 2.18 volts. What is the problem? I agree that 2.2 is not equal to 2.6, so they probably either messed up the number or the coefficient also changes with temperature.
But it is not going to give "the same" curve.

The % is indicating two things:
1. You must divide the number by 100, and
2. You must multiply the coefficient by the panel voltage spec you are applying it to. It is not a volts/c number is just a 1/c number dimensionally. That allows the same number to be applicable to all similar cells, regardless of the number of cells in the panel.

Taking one more stab at it, the coefficient lets you calculate V_T1/V_T2 = 1+ (K_V x (T1 - T2))