It is usually best to plan ahead when first installing solar. If you think you will upgrade in the future, discuss this with your installer who will take this into consideration when sizing your inverter. Solar array add ons can be retrofitted into an existing array, however.
In short, Yes!
The factors to consider when adding additional panels are:
- Are matching panels available for the upgrade? If not, are comparable panels available so they all match in voltage?*
- Panel size
- Inverter capacity (will your existing inverter work with additional panels or do you need to add an inverter)
- Space (do you have enough space for additional solar?)
One option would be to install a separate array with its own inverter if the current inverter is too small to handle the additional load. Both systems can be combined in your main AC panel or in your battery bank if you’re using energy storage.
*Note: If matching panels are not available and you must go with a different manufacturer, you’ll definitely want to stick with the same wattage. This is because they will only perform as good as the lowest wattage panels. In other words, if you had 185w panels installed years ago and you now want to upgrade to 330w panels, the 330w panels will only produce at the 185w level.