Update my older grid tied system

[DPP]

Guys, I need some advice please.
I want to replace my existing old generation enphase microinverters with Tigo optimisers. I also plan on adding another 16 550 watt panels with optimizers. I am planning on using EG4 Flexboss 21, Gridboss and internal battery.
My question is, will the Flexboss be able to handle all the panels?

 

[BentleyJ]

16 x 550W panels is only 8,800W.

FlexBoss21 can take up to 21kW of Usable solar and be over paneled up to 25kW. So unless the existing PV array is more than 16kW your proposed system should work.
According to the datasheet there are 3 MPPT inputs and 2 of them have 2 connection terminals so the variety of possible string configurations is quite flexible. Guessing this is where the name came from.

 

[DPP]

Thank you. Tigo support warned me that the inverter may have an issue because there is big difference in panel wattage compared to the existing 260 watt ones.
I used the sizing tool on Eg4 website. I have to split my existing 24 panels into two strings of 12. I am guessing I can you the 3rd MPPT for the string of 18 550 watt ones

 

[TechRider]

You might be able to put the 2 strings of 12 on one MPPT. I've got 6 total strings of 9 340W panels across 3 MPPTs. The sting of 12 gets the voltage in the proper range and then running them in parallel gets the current in the best range.

 

[BentleyJ]

Tigo support warned me that the inverter may have an issue because there is big difference in panel wattage compared to the existing 260 watt ones.

That may be true if you were attempting to mix panels on one MPPT. Don't do that.

I used the sizing tool on Eg4 website. I have to split my existing 24 panels into two strings of 12. I am guessing I can you the 3rd MPPT for the string of 18 550 watt ones

What would be the temp corrected Voc of 18 x 550W panels in series?

Edit: Voc on a typical 550W panel would be around 50V. 18 in series is 900V. Not going to work.

With 3 MPPT inputs, we can find a configuration that will work. Can you attach the datasheets for both the existing and proposed 550W panels.

 

[DPP]

Here they are...

 

[BentleyJ]

260W panels: Voc=37.7V, Impp=8.4A; 12 Panels in series=452.4V
Connect 1 string (12 panels) of the existing 260W panels to each of the 2 connections on MPPT 1 of the FlexBoss21. This takes care of all 24 existing panels. Total current on MPPT 1 will be 16.8A, well below the 26A usable limit

550W Panels: Voc=49.92, Impp=10.47A; 8 panels in series=399.4V
Connect 1 string (8 panels) of the new 550W panels to each of the 2 connections on MPPT2 of the FlexBoss21. This takes care of all 16 new panels as proposed to install. Total current on MPPT 2 will be 20.9A, well below the 26A usable limit.

MPPT 3 is available for future expansion.

 

[DPP]

Thank you so much Bentley

 

[Hedges]

If your original system was permitted before RSD was required, I wonder if installing new (string) inverter is allowed without adding RSD?
(new panels would probably still require them.)

260W, what model, how efficient? Going back far enough, panels were 12% and now some are 22%. Not sure about those used when Enphase showed up.
Consider removing all panels and figure out how many new ones would fit on the same mounts. Assuming rail mounts, which would allow that.

 

[DPP]

Guys,
These are the prices I am getting. But no support, like Signature Solar.

 

[Hedges]

Optimizers may not do anything for you.

Good to see the PowerPro price moving down. Some products just sit at original high price.

 

[SignatureSolarJess]

Guys,
These are the prices I am getting. But no support, like Signature Solar.

Hi! We're here to support you! Can I help?