Is it possible to add new panels to an old solar power system?

While solar modules are meant to last for very long time and their energy output only decreases slightly over time, it doesn’t mean that they’re fool proof.

Sometimes they malfunction and you will need to replace them. 

Or maybe your energy requirements change (you bought an electric vehicle) and you need to increase your electricity output, which means adding more solar modules.

But rapid technology sometimes makes solar panels obsolete and certain models may disappear altogether. 

In those instances, you will have to replace them or add new ones to your system.

If you’re replacing panels, the recommendation is to install modules with the same or similar amount of energy output as the original, so as not to cause disruptions or damages to your system.

For instance, if the original panels on your system have an output of 250W, the new ones should have the same output capacity.

Also, make sure the newer PV modules have the same number of cells in series and are the same type (mono-crystal or polycrystalline). It’s not recommended that you mix and match these different types of panels.

In addition, all solar panels must receive the same amount of sunlight when connected to the same inverter.

Talk to the original installer

If you’re adding panels to your existing system, you should start by talking to the contractor who installed your solar panels in the beginning. This serves two purposes: he knows the system best and can recommend the best addition for your array and this also means you won’t void the warranty on your system. 

He can help you calculate how many panels do you need to add to match your electricity needs.

If your installer is no longer available or has closed shop, you might have a little bit of resistance in hiring a new contractor to work on a project he didn’t install originally. 

Regardless of the case, you can also go to the Hahasmart price checker that allows you to check the price of a solar system for your home given your address and energy requirements.

Do you have enough space?

Another issue to keep in mind is how much space you have on your roof to accommodate those additional panels. 

If there’s no more space, another option can be to install a solar array on a ground-mount, carports, sheds or other structures within your property. 

If you go this route, you will probably need to connect them to another inverter, as you’re installing a completely separate solar array. 

Pay attention to your inverter

Inverters are also something to consider. They are matched to the amount of power generated by your solar array. If you add more panels, the one you have may not be able to support the extra energy. An overloaded inverter can lead to a blowout or power failure.

With a string inverter, new panels need to be matched to the existing modules. 

Generally, you are allowed to have a panel array with a peak power up to 133% of your inverter’s rated peak power. For example, if you have a 5kW inverter, you can have up to 6.65 kW of panels attached to it.

However, if you’re adding a considerable amount of new panels, it’s probably best to install a new inverter to handle this additional power. 

If you’re running your modules with microinverters, this might be easier, as the inverters go in each individual panel and replacing or adding modules won’t affect the rest of the array. Microinverters also allow you to install higher capacity solar panels than those in the original system. 

Something else to keep in mind is that if you add considerable amount of panels, certain municipalities may require you to submit further permit approvals for it.

While adding additional solar panels to an existing system it’s definitely an expense, you might be able to offset this cost.

You could be eligible to get an additional federal tax credit from your solar panels. It doesn't matter the year you originally went solar in, at any point you have the ability to get a new federal tax credit in addition to the one you already have. In other words, as long as the federal tax credit program is still in effect, you can get another federal tax credit. 

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