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# How to compensate for the cosine losses? Answered

I am working on a project related to Solar panels. I am measuring the Isc and I need to compensate it for the cosine losses. Can some body please tell me how to do it. Heard that it if fixed for every panel and is related to the geometry.

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Its "compensated" by aiming the panel normal to the sun ! That meand the panel has to track the sun.

Steve

Thanks for your reply, but I have the 3 years data from a PV module that is fixed and I need to compensate cosine losses for it. Any mathematical expression

First, please include those details back in the original text of this Question. As written, your question seems to be asking what you could build so that the panel doesn't get cosine losses when you operate it.

Second, how fine-grained is your data? Every few minutes? Hourly?

Do you know the location (latitude and longitude) where the module was installed? If you know that location, then you can (do a Web search) convert local civil time (what the clock shows) to local solar time (where "solar noon" is when the Sun is at its maximum height).

If you have fine grained data, then you can easily plot the current vs. local solar time and see the cosine structure, with maxima at solar noon and minima towards dawn and dusk. you'll also see the annual modulation as the Sun's height changes around the year.

Combining the annual modulation with the known latitude should be
enough for you to derive the tilt angle at which the module was installed.

If you do not have fine grained data (for example, you just have the total energy or charge output per day), then you have to take a more theoretical approach. Use the local time function computed above to create the local cosine function for each day. You can then integrate that to get the average (which for a perfect cosine is 0.5, of course). The reciprocal of that is the compensation factor you need to deduce what the maximum output was each day.

What you wanted wasn't clear from your original question.

Very tricky, unless you have accurate infomation about the panels original orientation.

You could actually estimate that, knowing the long and lat of the original location, and deconvolving the maximum output with the local noon/solar time.

Steve