Solar panels

[Mrcoolabah1au]

How do you read the back of solar good and bad brands

[pet-els]

Send photo's to T1.

PeterH

[T1 Terry]

Put the glasses on first
The information printed there is the STC recorded data the panel produced .... as long as the manufacturer is reputable and reliable and that they wouldn't falsify these figures
STC information is what the panel produced the most on the light box when flashed for 5 secs at a controlled 25*C. This test is used for comparing one panel with another, it has bugger all to do with what it will produce in the hot Australian sun. You need to understand that reading is the equivalent to the sun being perfectly angled at the face of the solar panel, so flat mounted on the roof you won't get these outputs unless the sun is directly over the top of the panel, no angle east/west/nth or south, directly over head. Now think about what time of day and yr that would occur, mid summer at midday, what are the chances of the panel still being 25*C inside under the glass and between there and the backing sheet. That is panel temperature, not the air temp or temp in the shade.

Remember, all these readingas are STC, not real life, I'll add the calculation figures to get an idea of what the hot panel will produce.
Vmp is the highest voltage the panel
Imp is the most amps it will produce as long as the Vmp is less that the maximum after the adjustment for panel temperature is made
OVC is the voltage between the positive and negative cable not connected to anything. There is zero amps output at this voltage.
ISC is the short circuit amps when the positive and negative cables are joined together, there is zero voltage available at these amps.
OVC and ISC is only used to check if the panel is doing what it should, allowing for panel temperature and sun angle etc. A good guide for testing second hand solar panels or if you think a panel might be dead or performing poorly.

Calculations for adjusting the STC Vmp to suit panel real temperature when in full sun.
This is available from the website of quality panel manufacturers, but even better, they will have a graph that shows the effect temperature has on the panel.
Have a look at this Australian solar panel manufacturer, Tindo, has publish on their site. https://www.tindosolar.com.au/wp-conten ... -sheet.pdf
If you scroll down to the graph on the left hand side showing the effect the temperature has on the panel output

Tindo Irradiance chart 3.jpg

The black line shows the STC results, up to roughly 30vdc the panel will put out its max Imp (amps) Any voltage less than that 30*C the current output will be still at the Imp rating .... as long as the inside of the panel doesn't get hotter than 25*C
The brown line shows the effect of the inside of the panel reaching 50*C, the Imp starts to fall off at 27vdc, 3vdc less than the STC rating.
The tan coloured line shows the effect of the panel internal temperature reaching 75*C. This is not an unrealistic temperature, even with the ambient temperature at 40*C. This shows the Imp start to drop at around 25vdc, 5vdc lower than the voltage advertised on the panel sticker.

As we start to see ambient temperatures reaching mid 40*C and higher, the temperature effect on solar panels will only increase, so even if the panels are in full sun, if it's hot standing in the sun, don't be surprised if the solar isn't working as well as you would expect.

T1 Terry

[supersparky]

T1, thanks for the concise technical explanation. As usual, correct and to the point.

Wayne, what is it that you really need to know?

[Mrcoolabah1au]

Just checking as a friend is thinking of upgrading he look a stuff on gumtree and the other sites The big E