How to add more solar to an existing grid tied system

[Lexx]

We currently have a 4.2 kw grid tied system on the roof, with 250 watt Sharp panels, and a central Sunny Boy inverter. The Sharp panels were replaced under warranty in 2015, The Sunny Boy inverter looks very old and predates our acquisition of the property in 2013.

I would like to essentially double the size of our existing system. I've received varying opinions as to how to do this. Some say to build a completely separate system. Others have stated that we can install a new array of panels and use an inverter with dual-MPPT channels.

The new panels could either go on another part of the roof of our house, where the existing panels sit. Or they could go on the roof of our detached garage.

One thing to note, is that we have a 400 amp split main panel, with 200 amps going to one part of the house, and another 200 amps running to a subpanel in another part of the house. The garage has another subpanel of its own.

One issue may be that we are now out of circuit breaker positions in the subpanel that my existing solar system is attached to. The garage subpanel has room for one more 50 amp breaker. But I'd like to be able to have a charger for our Tesla installed, and that will need a breaker of it's own.

I appreciate any input.

 

[sunshine_eggo]

Step 1: see if your utility allows it based on your current agreement.
Step 2: see if addition requires compliance to newer standards. If so, see if you must bring your prior system up to spec.

If 1:yes and 2: no, THEN start looking for solutions. Otherwise, you may find the added expense of bringing your old system up to the current spec may change the financials to the point of intolerance.