Adding panels to an existing system

[jcoop0001]

Hello All,

Currently have a 10.6kw system consisting of 40 Canadian Solar 280w panels with optimizers, Solar Edge 10k inverter. Have 3 Tesla Powerwall batteries in the system as well. With this we could be "independent" apx 75% of the time. When winter rolls around batteries will get 30-40% charge most days.

I want to add some more panels but my inverter is pretty much maxed out and would have to use optimizers with the solar edge inverter.

I have 14 more new 400w panels and a EG4 6000 inverter that I thought would work. The solar edge is a 220v split phase inverter and the EG4 is single phase.

Can I feed the EG4 with the new panels and connect the whole thing to the same line that feeds the home from the array? Have 2/0 cable feeding the home.

Not sure how things will work with 220 and 120 mixed.

Thanks John

 

[chrisski]

I did not get the Tesla PowerWall because it was not a very good option to run in case of a black out for days on end. Perhaps someone who has one and has done what you want will show me the error of my ways.

I have 14 more new 400w panels and a EG4 6000 inverter that I thought would work. The solar edge is a 220v split phase inverter and the EG4 is single phase.

Can I feed the EG4 with the new panels and connect the whole thing to the same line that feeds the home from the array? Have 2/0 cable feeding the home.

I don't see how that would be possible to charge the Tesla Power Wall with a single Phase EG-4.

-The PowerWall is an AC coupled battery that has the inverter inside the powerwall to take the AC to a DC chargeable voltage, so you can't hook the DC up directly.
-I don't see how a single phase AC could charge the Powerwall, never mind getting the EG-4 to Synch in Phase with the SolarEdge.

I opted not to go with the Tesla PowerWall because of those reasons and it can't be charged off a generator.

 

[Hedges]

You can probably put about 15kW (STC) of panels on a 10kW inverter with little to no clipping.
If two strings of different orientations, maybe 20kW (STC) of panels.

You can generally parallel multiple GT PV inverters. They may work OK with multiple PowerWalls, I'm less familiar with how they interact.
Do you have a Tesla backup switch?

If the EG4 6000 is a hybrid, should be able to set it up to supply a protected loads panel. I think it is an off-grid hybrid, won't backfeed but could probably draw from the PowerWall system if that provides backup. Backup downstream of backup, basically a UPS with PV.

https://eg4electronics.com/backend/wp-content/uploads/2023/10/EG4-6000XP-Inverter-Spec-Sheet.pdf

I'm no fan of Solar Edge, but maybe a second string of PV panels with optimizers would be the way to go.

 

[jcoop0001]

Knowing what I know now I would not have used the Solar Edge with optimizers either. It was done about 8 years ago so it is what it is.

The powerwalls do have the Tesla gateway "transfer switch". It works fine, we paid very little for them, otherwise would have went a different direction as well.

Will look into adding about 2400w to existing inverter. It may "clip" in the summer, but the winter will be fine, that's when I need the extra output.

 

[Hedges]

It should support some number of additional panels in series (I think total of 30 or so), and I think 2 strings in parallel - do you have 20s2p array?
I would think 50% increase, added 5kW, would fit its voltage and power limits pretty well.

 

[jcoop0001]

Not sure of the string configuration, it was "professionally" installed. Will have to do some digging around on that to see how it's configured.

 

[Hedges]

With inverter disconnected, I think the optimizers put out 1V each. So voltmeter would reveal configuration.
But I think they may also support parallel strings of different length.

Check the manual. I only have a little familiarity with it from reading.

Do you have a monitor that shows performance per panel, and maybe physical location on your roof?

 

[jcoop0001]

Ground mount system, I can check the output of each panel at the inverter I believe.