Using Sol-Ark to extend a small system

[jmzorko]

Hello, all ...

I purchased a home recently with a 3kw PV system using a Delta Solivia 3.8TL inverter. I want to add another 4kw, but the original installer is no longer in business, and I want to use the current 3kw system to help charge the batteries should the grid go down. Everything I've read so far indicates that the Sol-Ark (8 or 12) will allow me to do this via AC coupling the current Delta inverter to it. Will this work?

Also, can the Sol-Ark work with multiple battery types simultaneously i.e. if I connect an LG Chem Resu10h now and want to expand - or just experiment - with adding some used Leaf batteries or something in the future?

Regards,

John

 

[robby]

Yes it will work with the AC coupling. Sol-Ark just released a 5K inverter if you want to save money and don't plan on expanding.

Multiple different batteries will not be so straight forward and it certainly will not work with mixed chemistry battery types. I had also looked at the LG Chem Resu10L which is the 48V version that would work with the Sol-ark. The H version is 400Vdc and will not work with the Sol-Ark. Bottom line was that every single person I talked to tried to steer me away from LG and thank God they did. The Lithium ion batteries used in the LG are outdated compared to Lithium Iron Phosphate Batteries. You will get a lot more cycles and Power with Iron Phosphate Batteries for the same or a lower price. If your going with the Sol-Ark I highly recommend you look at the Fortress eFlex and get two of those. It costs a bit less than the LG, has a better build quality and interfaces and it's BMS data talks directly with the Sol-Ark. Second big bonus is that they have a better warranty and unlike LG, they will warranty the battery no matter who installs it. LG requires a certified LG installer put in the battery or you will not be under warranty.

 

[Hedges]

https://filecenter.deltaww.com/Products/Download/05/0505/Manual_Solivia%20TL_V06_170807_s.pdf

What I looked for and didn't find was "frequency-watts", an optional feature of UL-1741SA. I only found mention of standard UL1741.
With frequency-watts the GT inverter will linearly ramp down power output as frequency increases, allowing battery inverter to manage the system cleanly. Without that, when frequency is increased above 60.5 Hz the GT inverter shuts off and stays off for 5 minutes.

If that feature isn't available, I suggest either replacing the GT inverter with one that is, or rewiring PV panels to your battery inverter (such as Sol Ark.) Doing that, you may or may not have to deal with "Rapid Shutdown", if that feature (and added box per PV panel) is part of your system.

I use SMA Sunny Island and Sunny Boy for AC coupling. Works nice now that I've got models with frequency-watts.

 

[jmzorko]

Alas, the Delta inverter seems to have died. I found a local installer who installs the Sol-Ark, so I'm hoping to replace the likely-dead Delta with the Sol-Ark very soon. I've a question about PV oversizing, though. Does oversizing work with the Sol-Ark similarly as it does with other inverters i.e. putting more panels up with an amalgamate total greater than the the inverter's rating to generate more watts during morning / evening / winter? Or is this what the Sol-Ark smart-load connection is for?

 

[robby]

Alas, the Delta inverter seems to have died. I found a local installer who installs the Sol-Ark, so I'm hoping to replace the likely-dead Delta with the Sol-Ark very soon. I've a question about PV oversizing, though. Does oversizing work with the Sol-Ark similarly as it does with other inverters i.e. putting more panels up with an amalgamate total greater than the the inverter's rating to generate more watts during morning / evening / winter? Or is this what the Sol-Ark smart-load connection is for?

You cannot exceed the max input on the mppt's using strings of panels but Yes from what I gather you can AC couple additional panels that are running from Microinverters.

 

[jmzorko]

You cannot exceed the max input on the mppt's using strings of panels but Yes from what I gather you can AC couple additional panels that are running from Microinverters.

Does this mean that the Sol-Ark doesn't clip the same way that other string inverters do? I just want to capture as much sunlight as possible from one side of the roof (the "evening" side as the roof slope faces towards the west) as I do from the the other (the "morning" side). If I get, say, the Sol-Ark 5K, and put another 3kw string (as an example) on the "evening" side of the roof, will the effect be similar as that by other string inverters (i.e. generate more power when the sun is lower in the sky and clip at midday)? Since the Sol-Ark 5K datasheet indicates a max PV of 6.5kw yet a max continuous power of 5kw, is the other 1.5kw (if available) clipped, or does the Sol-Ark send it to the smart load connection (if present), or something else entirely?

 

[Keith Moreau]

In talking with Sol-Ark's support, it seems that they don't want you to 'clip' much. I've discussed this very issue that you have raised, where you want to saturate the MPPT / inverter so you get more power at other than peak sun times, and during peak sun times, you max out or 'clip'. It seems they don't' want the total panels to be more than the voltage and current they've specified, and that too much voltage won't just clip, it will damage their system. Not sure where you are located, but in very cold climates, there can be a spike that occurs in the early morning, when it is cold but there is bright sun. The the cold can make the initial transient voltages spike above their maximums (in my 12K model I think this is 550 volts) They said if this happens damage to the Sol-Ark can occur. I'm not in a particularly cold climate so I don't think this will happen to me, and I also don't have east facing panels, they are facing south, so I'm not worried about this. But it may be a concern to you. I'd suggest giving Sol-Ark a call about your particular situation and what you are thinking.