Looking at options for upgrading existing system

[jcoop0001]

Current system is just over 7 years old and consist of the following

40 Canadian Solar 265w panels
1 Solar Edge 10k inverter
Ground mount racking
40 panel optimizers
3 Tesla Powerwall Batteries

System has and is working great, about 60-75% of the time we are able to get a full charge on the 3 installed Tesla powerwalls. Late November through march we are not generating enough to get a full charge on the batteries, sometimes as low as 20%.

My first step is I would like to add about 5k in panels, I have some room on the existing rack system and have the room to expand it as needed. My inverter is a 10k and I have 10.6K in panels. I have never seen much over 10k of output, most of the time it's around 7-9k in the summer months. I'm guessing I could add 3k to the inverter and it may "clip" occasionally but not very often and it would help me get to a full battery charge on the days when it's cloudy.

So first option in my mind is to add 3k in new panels and see how that goes.

2nd option is to replace the Solar Edge inverter with the EG4- 18K, add 6k or more in new panels, rewire the existing panels to delete the combiner box maybe. Know the EG4-18 has a much higher input voltage than the old solar edge.

I have had a couple installers tell me the inverters are good for about 10years max so Im not that far away. That is one reason I am considering replace it.

Please share any thoughts.

Thanks John

 

[FilterGuy]

One issue you are going to face is the optimizers on the panels won't work without the solar edge inverter. There are several options to deal with this:

1) Remove the optimizers and not have rapid shutdown. If you need code compliance this may not be an option
2) Replace the optimizers with either Sunspec compliant RSD receivers (No optimizers)
3) Replace the optimizers with Tigo or another brand that does not require the special inverter.
4) Find a Solar Edge Safety an monitoring Interface (SMI) box....This will keep the optimizers working without the inverter.... but all reports indicate the SMI is not available in the US.
5) Find a Solar Edge KEY that will program the optimizers to work without the inverter... but this disables the Rapid Shutdown function.
6) Keep the Solar Edge inverter and AC couple to the 18Kpv.... but that kinda defeats the purpose of getting the 18K.

 

[zanydroid]

Wouldn't a 7 year old system have a good shot at predating the panel level RSD code? I don't know what the rules are for grandfathering. Also this is a ground mount system so RSD is further relaxed. And the ground mount gives more rational opportunities (IE ROI on labor cost and annoyance) to reconfigure MLPE and string compared to rooftop.

Are the optimizers required due to site conditions or are they just there because the installer wanted to install SE for you (easier for them to perform up to spec without wasting time thinking while also making more money)?

 

[zanydroid]

What is the thinking behind using 18k instead of the cheapest grid tie inverter that complies with your POCO and is compatible with your powerwalls? The 18k is redundant to your powerwall's internal storage inverter unless you need more advanced capabilities for backup, shifting, or whatever

 

[jcoop0001]

Well,

Knowing what I know now I don't think I would have gone with the SolarEdge inverter. Looking back there was no good reason to do that, there is zero shading so I suspect they really were not needed.

I don't have a problem leaving the original system in tact and just adding to what is there. Originally I was thinking of adding 2 of the eg4-6-5k-off-grid-inverter-6500ex-48 in a split phase configuration. Eventually I do wish to add some DIY Batteries to this as the budget allows. Adding another powerwall would be an option if the cost comes down in the near future. With this option I can still get my 5-6k of additional panels which should be closer to toping off the batteries on those not so sunny days.

Thank you all for the information, there is much I need to learn for sure.

Keep it coming

Thanks John

 

[jcoop0001]

Oh,

I believe those inverters are primarily off grid inverters, but with the powerwalls and the Gateway all ready in place so the grid is protected during grid outages. I should be able to run these as a parallel system with the 10k solar edge. Please correct me if I'm wrong.

Thanks Again