Mixing different solar panels

Hodgepodge of solar panels
Hodgepodge of solar panels

Like many people starting out going off-grid, your pocketbook is being pulled in many different directions, so you buy a few solar panels to get started, then later on you add to them, it’s easy to end up with a hodgepodge of different solar panels on your roof. We are certainly guilty of that ourselves. We started out with four 55 watt Siemens solar panels, we bought them used on Craig’s List. We added a few Harbor Freight solar panel kits, eventually ending up with many more HF kits (thanks Seth!).

Hooking up the different sizes and types of solar panels has worked for us, it’s kept us going for nearly 8 years now, we did purchase a good charge controller, it’s a Xantrex C35 so it can grow with us. But now it’s time to start focusing on upgrading our solar panels and getting the same size and kind to work together. We will “retire” our current panels to another building on the property.

Why is this a problem? Well, it’s not a game stopper, but it is not ideal, we aren’t getting the most out of our system. It’s the weakest link scenario, your solar panels are only as good as your smallest/weakest panel, same thing goes for batteries, it’s not good to mix different types and sizes, it’s not good to mix different sizes and types of solar panels.

It’s not forbidden, but it’s not recommended, it will work, but overall it will drag your system down, your bigger panels will not work at their peak performance, think of putting tiny tires on a race car, it can work, but not at its best.

Here are the ones I’m looking at as replacements:

Another upgrade I’ll do is to get a MPPT Charge Controller, these squeeze more juice out of your existing system, IF your panels are the same size, apparently having varied panels on a MPPT charge controller will still drag the entire system down. I have been reading about this type of charge controller and they have come down in price, I’m very interested. How about you? What are you using and how is it working for you?

You can learn more about the pros and cons (mostly cons) about mixing solar panels here:

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4 Responses

  1. I can’t claim that one as my wife did those. She uses two android apps on her phone, all part of being minimal and getting the most out of your devices. She uses Photo Grid mainly, but also uses PhotoCollage.

  2. The MPPT controllers only give maximum benefit when you use solar panels that have a large Vmp. These are usually the 200W and over. They are also good if you wire your panels in series to reduce cable size. Hope this is useful.

    1. Thanks Mark, that is good info to have, didn’t know that, chances are I’ll be upgrading my panels first, then later going for the MPPT controller…

      Love your site BTW, what do you use to make the image mosaics?

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