Photovoltaic Cells In LTSpice

We like to build things using real parts. But we do think the more you can model using tools like LTSpice, the less time you can spend going down dead ends. If you need to model a common component like a resistor or even an active device, most simulators have great models and you can tweak them to have realistic parasitic effects. But what if the component you want isn’t in the library or doesn’t have the fidelity you want? [FesZ] wanted to model photovoltaic cells and had to build his own model. The resulting two videos are well worth watching.

Building your own models in Spice isn’t necessarily very difficult. However, knowing exactly what to add to model different real-world effects can be challenging. The videos do a good job of showing how to mutate a simple diode into one that produces current when exposed to light.

The key, it seems to us, is to not fall too far down the rabbit hole. The default models, for example, do a good job of modeling major effects but not getting bogged down with subtle details that don’t make much practical difference. You usually want to capture major effects in normal operating regimes. The fact that your resistor will blow open if you draw 30 amps through it isn’t really important for most simulations.

We’ve looked at building transformers in Spice before. We also enjoy modeling test setups with LTSpice.

19 thoughts on “Photovoltaic Cells In LTSpice

  1. Headed down the renewable power electronics rabbit hole? There are buckets of educational resources, though one course I’m finding ‘just right’, hails from the Indian Institute of Science in Bangalore:

    1. Disappointed to learn that for one’s investment in solar panels, you merely rent utility for a short time. Accumulated UV light exposure then renders them so inefficient as to be of practically no use. No accident, but planned adhesive degradation, or ‘browning’.

      I have an archaic, adhesive-free, glass sandwich panel, that even today produces near it’s full specification.

      It is expected that we will have 78,000,000,000-kg of solar panel waste on our hands, by the year 2050! Thanks, you know who.

    2. Incredulous of the comments on media appropriateness. Do an awful lot of learning, and for varied purposes, and you’ll gain an acute appreciation of the ‘best’ method to acquire information. There isn’t “one”.

      As for FesZ presenting his tutorial as a series of videos; there may be textural presentations on the subject matter that some visitors will prefer, but as a means to also assimilate HUGE amounts of proficiency with LTSpice, in miniscule time, you won’t find better.

      FesZ has read the Spice manual for us, and anyone who has done the same, will understand what a great service to his following that is.

      Simulator manuals, in text form, suck to have to wade through as a first time learner, but then come to the fore when you do need specifics.

      DGMW, I’m up for a good read, too. The mastery of particularly scholarly topics is best achieved through multiple perspectives. That means 2, 3, or even more sources, that each cover the same material.

      Yet, ‘How to re-string a line trimmer’ is going to send me looking for a 2-minute YouTube video.

  2. I can’t believe it’s easier for people to make videos instead of just writing the stuff down. Why do they do this?

    Why are we seeing more and more content like this in video format? It’s slow, low information rate, hard to browse, hard to index, hard to search, voluminous to store

    It is inaccessible to many, and at least inconvenient to many more.

    Is the incentive monetization of youtube videos? Fame?

    Is there genuinely a preference for video over text+figures?

      1. Right. Now try to replicate the things from the video locally.

        See how much time you waste scrubbing back and forth in the video? Notice that you have to note things down from the video or make screenshots to refer to?

        It isn’t about being old. It’s about video not being well suited to teaching or learning.

      2. If “getting old” means preferring the intellectual equivalent of well-prepared meaty steak over spoon-fed watered-down pablum, then bring it on.

        Also getting old beats the alternative.

    1. I think you are right. And you don’t even mention the quality of the videos (wobbling cameras, poor sound, poor speakers with a lot of ähm ähm, not concentrationg on the subject, sloppy language, and very often formulations very close to being completely wrong). Writing on a subejct is a tedious and hard job. Writing is not a linear activity, you can move back and forward, to refine your formulation. But the result rewards the writer and the reader equally. Writing is one of the best quality control tools. Videos may be a valuable addition to show certain things (physical phenomena, …).

    2. The thing of it is that you really have to prepare a script and collect materials (pictures of diagrams and stuff like that.)

      Making a video includes all the work of making a written description, then videoing and editing afterwards.

      The video makers could just save themselves the hassle of making the video, and just concentrate on making the script and the other materials better. The final product (without the video) would be of more use and far more accessible.

      But, nope. It’s got to be video.

      As bad as sitting in a classroom, listening to the instructor drone on for an hour about things you could read and comprehend in 10 minutes. Fast forward and scrubbing helps a little, but not enough.

      There’s a place for videos. The transfer of detailed technical information ain’t it.

      1. I agree with you. But I understand the reason…

        I believe the problem really is the monetization of videos. They need to produce videos frequently (as far as I understand you earn more based on the visualizations in the first 24h…), and because of that, the quality sometimes is questionable (they have a short time to produce new material).

        I also do not like the excessive “segmentation” of content… For example, in a channel about microcontrollers, instead of having a logical sequence of content, they usually have random stuff like “heeey let’s talk about the Arduino millis function” (and they extend the subject the minimum time required for a video). That’s the only way they can produce videos 3 times per week.

        I also do not like that SURPRISED face on most thumbnails, hahaha, but that’s also part of the strategy…

        1. Oh, don’t get me started on the stupid looking faces of all those videos.

          I a very simple rule. If browse/search for videos and the thumbnail for a video shows a stupid looking face on it, I block the entire channel on Youtube.

    3. Everything is being done geared to today’s younger crowd. They eat and breath videos on their phones. That is why Despite blockers of all sorts, news sites insist on playing videos as soon as you open the page and the video parroting what you are reading on the page pops off to the side as you scroll down.

      It is annoying as f**k, but it’s the that demographic ingests. As a consequence of this, the list of URLs in my browser’s javascript blocker is super long. Because the only way around it is to entirely block javascript from those pages.

      Plus the potential for monetization.

  3. As far as I see the model is missing a capacitor in parallel to the current source. It has to be about 900nF*V/I at the MPP for common silicium-based cells, but may vary about one order of magnitude depending on the actual working point. This becomes relevant above about 2 kHz, and may affect the MPP-tracking if you are too fast with it.

    For further reading on the capacitance: Kumar, R.A.; Suresh, M.S.; Nagaraju, J.: Effect of solar array capacitance
    on the performance of switching shunt voltage regulator. In: Power Electronics,
    IEEE Transactions on , vol.21, no.2, pp. 543- 548, March 2006
    doi: 10.1109/TPEL.2005.869779

      1. Sorry, I stumbled into that problem a dozen years ago and followed that rabbit hole just deep enough to get a works-for-me approximation. Afterwards I put that paper into the bibliography, which led me in and out of it (as far as I remember the paper was more about the semiconductor properties than simulating a real PV-cell).

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