Five Ways to Mix and Match Solar Panels

Mixing and matching solar panels can be very useful at times. For example, a mixture of large and small panels might help you fit the most capacity onto a small roof. Or you might want to add extra panels to an existing solar panel system. However, mixing and matching solar panels can cause problems when not done correctly. Most likely, you’ll end up with sub-optimal power output. In the worst case you could even make your system unsafe. However, it is possible to make different models of solar panels work together safely and effectively. Read on to learn the five ways to do this:

1: Use a Microinverter for Each Solar Panel

A microinverter allows each solar panel to work independently of all the others. This means that with microinverters, you can mix and match solar panel to your heart’s content. This is the ultimate solution for mixing and matching solar panels.

Solar panels of with varying characteristics with a microinverter for each.  A tick mark indicates that using microinverters is a valid way to let you mix and match different solar panels.
Microinverters give you maximum freedom to mix and match solar panels. Image License: CC-BY. Credit: energyd.ie

2: Use Power Optimizers

Power optimizers let each solar panel in a string work at its own preferred voltage and current, regardless of what the other panels are doing. Power optimizers should work great if all of your solar panels have the same number of cells (all 60-cell or all 72-cell). However, you will need to check the datasheet if you’re planning on mixing 60-cell solar panels with 72-cell solar panels in the same string.

Solar panels of different makes and models connected in a string, each with a power optimiser.  A tick mark indicates that using power optimisers can let you mix and match solar panels successfully.
Power optimisers let you mix and match solar panels on the same inverter string. Just be sure to check the datasheet if you want to mix 60-cell panels with 72-cell panels. Image License: CC-BY. Credit: energyd.ie

3: Different Solar Panels on Different Strings

Many solar inverters allow for two independent input “strings”. This allows you to use two different kinds of solar panels, one on each string. Alternatively, you could use two separate inverters.

Two strings of solar panels connected to a solar inverter.  Each string is made up of a different kind of solar panel.  A tick mark indicates that using separate strings is a valid way to mix and match solar panels.
Dissimilar solar panels won’t interfere with each other as long as they’re kept on separate strings. Image License: CC-BY. Credit: energyd.ie

4: Different-Sized Solar Panels with the Same Cells

Some manufacturers produce two sizes of solar panels made with the same cells. For example, they might both 60-cell and 72-cell versions of the same solar panel. Panels with different numbers of cells work fine together as long as the cells themselves are the same.

A string of solar panels.  The string is made up of solar panels that have different numbers of the same cells.  A green tick mark indicates that you can use solar panels with different numbers of cells together, as long as the cells themselves are the same.
Panels made with different numbers of the same cells will work fine together. Image License: CC-BY. Credit: energyd.ie

5: Solar Panels that are Similar Enough

Did you know that no two solar panels are ever exactly the same, even if they’re the same model? While it’s best to match solar panels in a string as closely as possible, a very small difference between panels will only lead to a very small difference in power output. Sometimes, the differences is small enough that it doesn’t cause any problem. This makes it possible to mix solar panels from different manufacturers, as long you’re extra careful to make sure that they’re very similar:

Check the datasheets for both solar panels that you’re planning to use together. In particular, pay special attention to short circuit current, maximum power point current, and bifaciality. These numbers need to match very closely (within a few percent). Temperature de-rating values, the shapes of the I-V curves, and the power output guarantee should also be close. The two panels should work fine together as long as all of these values match. You don’t need to worry about voltage or number of cells.

Note that the performance of a solar panel string is generally limited by the panel with the lowest current. Therefore, if you’re adding one or two more panels to your string, it’s better to go for slightly higher, rather than slightly lower, current ratings. On the other hand, if your panels are getting old they may have already lost a few percent of their power output capacity. In this case, you can afford to go for panels with current rating that’s a few percent lower (approximately 1% for every two years of age).

A string of solar panels made up of panels that are not identical, but are very close in terms of electrical characteristics.  A green tick indicates that you can mix different makes and models of solar panels if the electrical characteristics match within a few percent.
Different models of solar panels work fine together if the electrical characteristics match closely. Image License: CC-BY. Credit: energyd.ie

Conclusion: Mixing and Matching Solar Panels is Possible

Mixing and matching solar panels can lead to poor results if not done carefully. However, there are ways to make different models of solar panels work well together. A professional solar energy designer can help you with this. Make sure to contact us for your free solar energy consultation for help with designing the perfect solar panels system for you.