Solar Clipping and why it is happening

I’m Justin and today I am going to be discussing Solar Clipping. In this article, I will show you what it looks like on a graph and discuss the impact it is having on my solar power production. Welcome and thanks for stopping in, don’t forget to leave me a comment below.

Will Solar Clipping Damage the System?

No, clipping doesn’t damage the solar array or inverter. Clipping doesn’t damage your battery storage if you have a battery backup. When clipping occurs you are simply losing power that was generated but you could not capture.

My Solar System Components

A quick rundown on the setup I have here. I design, permitted, sourced, installed, and commissioned the system. I even become a certified Enphase installer during the whole project. By doing this I saved 10’s thousands of dollars. I made a video on what the total system cost me down to the penny. If you are interested in that here is a link to the YouTube video I made on that. ( https://youtu.be/oNew5HiQicE )

After months of research and trying to find the absolute best bang for the buck I picked up 27 – S-Energy SN370M-10T Solar panels. Each rated at 370w. For a total of 9990 watts. I paired the panels with Enphase IQ7+ microinverters. To be very transparent and honest, I was finding awesome deals on the IQ7+’s so my judgment was heavily influenced by the amount I would save going with those. Price had a drastic impact on me picking the IQ7+ model over the IQ8+ or even the IQ7A and definitely the IQ8A.

What we all need to take into consideration is that solar panel’s likely to peak at around 90% of their rating straight out of the box. Then degrading about between .6% and 1% annually. That is why the IQ7+ made sense to me for my design. For those of you that are just learning about all this – The IQ7+’s are compatible with solar panels that rate all the way up to 440w. Don’t get that confused with its output rating though. The max peak output for an IQ7+ is 295w and the continuous max is 290w.

You also need to factor in things like the tilt of the array, time of the year, clouds, dust, number of peak sunlight hours, even bird droppings, and so on. Under perfect conditions, in real-life usage, a solar panel rated at 370w would most likely peak around 330w.

What Does Solar Clipping Look Like?

Let’s take a look at a couple of examples using my Enlightened Manager. I choose Sept 29, Sept 30, and Oct 1^st. You will see flat tops on each of those days. Generally, the max production is happening from around 12:45 pm until around 2 pm. Flatlining at just around 7900w.

If we take a little longer view we will see that we only peaked on those 3 days out of the 7 day. Although my system is clipping some, I am still very happy with the production we are getting out of this setup vs the cost we paid for it.

If we take a little longer view we will see that we only peaked on those 3 days for that week. Although my system is clipping some when it is extremely sunny, I am very happy with the production of the IQ7+’s paired with the 370w S-Energy panels.

Pairing Solar Panels and Microinverters

A typical DC to AC ratio (array to inverter) is around 1.1 -1.2 to 1, i.e., the array is slightly larger than the inverter capacity. This means that DC power from the array is maxed out on a bright sunny day, there is energy lost because the inverter is not capable of converting all the DC power into AC power.

If you want the system to be fully powered for 20 years, you want to be at least 13% oversized because of lifetime loss and sun variability. At latitudes farther from the equator with less available sun, up to 30% excess panel capacity is advised.

There are so many variations to consider when designing a solar system. Sizing your panels and micro-inverters is one of the most important elements.

How often will clipping happen?

In a properly designed system, clipping should only happen for a small percentage of time each sunny day, so energy loss is kept to a minimum due to clipping.

Is solar clipping normal?

No, solar clipping is not “normal”. However, some systems may clip and others may not. It’s the difference between how much solar power you have available and how much you can process.

Let me be clear, I didn’t know much about clipping when I started my solar project. Probably still don’t as much as I should but I want to share my experience with you all so that we all can learn.

The Conclusion

Although my system has clipped the cost differences in hardware made up for the loss of production on those days the system clips for about an hour. I don’t worry about that because although I showed you an example where it has happened 3 times in a week if my software would let me graph 30 days it would show that it only happened 5 times in 30 days. That is not terrible. Being that I saved nearly $3000 going with these IQ7+’s I would have not recouped that over 25 yrs at this rate.