2 PVPowered 3500 Grid Tie Inverters powering my home.

You need to have a large enough Main panel to add ~3x 20 amp breakers and not exceed the panel's rating...

For example, 200 amp panel * 1.2 solar allowance = 240 Amp total (main breaker+solar breakers). So, if you want to add 3x 20 amp breakers for 60 amps total, you would need to change the main breaker to ~175 amps which gives you room for 240a-175a=65 amps for solar breakers.

Details matter here... So, you need to look up the rating of your 3,500 Watt GTI inverters and what breaker they need (appear to be 20 amps from quick search).

You also need to check with your utility--They may have a limit for 10,000 Watt GTI system -- Above which may have more regulations (and different pricing plans).

The other possible issue... If you have a long cable run from home to the pole transformer and relatively high AC line voltage (~255 VAC or higher), it is possible that the voltage drop (actually voltage rise) can trip the GTIs (overvoltage trip voltage is generally 260 to 265 VAC).

Each GTI inverter should have all its panels on the "same plane" (don't point some panels SE and others SW, or different tilts). This will reduce output harvest.

Otherwise, following code, good grounding practices (including lightning control, if an issue in your area), GTI systems are as simple and inexpensive way you will find to harvest solar electric energy. There is nothing you need to do other than keep free of tree branches, and weeds (if ground mount). Lightning and hail storms can be a real problem... And reflections from large arrays into nearby homes can also be an issue for those in the other homes.

-Bill

Skip,

Sorry, I misread your first post... You are just looking at 2x 3.5kW GTI systems... The math still holds, just different number(s) of circuits.

The solar GTI breakers are installed in the main panel (or sub-panel feed to main) at the opposite end of the bus bar from the main breaker/utility input connection. For older homes, installing a new sub panel for more breaker/increased capacity is an issue--And increased main breaker capacity can be held up while the utility figures out if your local distribution grid can handle the additions/changes.

Check very closely your rate plans... Today, most utilities are actively working against the present (subsidized) grid tied solar systems (buying and selling power at retail... The utilities want to buy your power at wholesale and resell it back to you at retail).

Besides charging the game near term (or 10 year grandfathering your present system rate plan), they are also doing things like jacking up connection charges from $5-$10 per month (happened to me a couple years ago) to upwards of $48 to $96 in a few places.

-Bill