Advice for upgrading my existing Grid Tied Residential Solar system

[captcarib]

Hello all,
I am in the process of planning an upgrade my existing grid tied solar system. I currently have 6,200 watts PV array on my main roof tied into a SB6.0-1SP-US-40 GTI and I recently installed a second 2,600 watt PV array down at my pool cabana roof tied into a SB 5000TL US GTI. I want to upgrade my system to include whole house battery back up power, zero consumption with grid export. I really dont want a critical loads sub panel setup, whole house circuit back up is preferred. I am on the fence abo AC coupling vs DC Coupling with regard to charging my battery banks. I know my older Sunnyboy 6.0 only supports UL1741 and not UL1741SA or SB but I think the newer Sunny boy 5000 TL does? I am leaning towards an Outback Radians 8048 Hybrid inverter, which I could setup either way. Will just relying on UL1741 with no watt limit/freq. shifting damage my battery bank if I go AC coupled route? Would a hybrid system be better in my case? DC Coupled at main roof and replace older SB 6.0 GTI with Outback FM100 MPTT controllers and then leave pool cabana AC coupled as is? Will the DC coupled main roof system be able to provide grid support 240V AC that will enable the SB 5000TL to stay on during a grid outage and keep producing power? I am looking at Lithium Iron Phosphate batteries. Any advice or tips would be greatly appreciated.

 

[glandpuck]

Ah. This is up my ally.

I ran an Outback Radian 8048A for 8 years. Outback is grade A top notch and mostly worry free. However, it is not NEMA 3R, so indoor (garage plus) installation only. Also, the Radian by itself doesn't function. You need to purchase and Outback Mate, Hub and if charging from solar, some type of charge controller, which the Outback Flexmax controllers are the best. Since you currently do not have any microinverters, then AC coupling would not be a cost or time saver for you. And remember, your current string inverters are using high voltage input and Outback charger controllers are limited to lower voltages than other brands. This means your panels will have to be rewired into proper serial/parallel combinations with a new combiner box installation and breakers, fuses, etc. That's a lot of labor and cost. Outback Radian also has no closed loop battery support. If installing lithium batteries, then Simpliphi and Pytes play nice with Outback. Once your Outback ecosystem is in place, the system is programmed via the Mate interface of by the website.

Now that that part has been answered, I think your best move it to remove the SMA inverters (they have very little value) and install a Hybrid inverter. Hybrid inverters can accept a DC input to about 500 volts. this will mean connections from the current strings of panels will be much simpler to achieve. I think the best choices are Sol-Ark, EG4/Luxpower and now probably Midnite solar. I say this because Sol-Ark is pretty good at being a dependable inverter from the build point and offers very good technical support and lastly the programmable software, IMO is the best. Midnite solar is a company in the PV business for many years, still answers the phone and is known for making many quality products that last. EG4/Luxpower offers great value and pretty solid hardware at a lower price point than Sol-Ark, but I think their software and tech support is a little behind.

SMA is now offering new hybrid inverters at excellent price points. They do not have a fan for cooling, it is all convection and heat sink. They are space saving, easy to install, priced well and fully featured. To me, their biggest limitation now is using high voltage lithium battery inputs and only can be used with the BYD battery stacks. BYD is top notch.

All of these hybrid inverters offer 240V split phase and can have their output be wired directly into your main panel. They will then provide backup power if the grid goes out to the main panel only if you have transfer switch between the grid input and the main panel/inverter so the grid cannot be backfed by the inverter when the grid is out. I'm not certain if this is up to code though. Consult an electrician.

Also, all of these inverters, except SMA Hybrid, use low voltage batteries offering a great deal of capacity and also closed loop control which is essentially plug and play like a USB port on a computer.

And generator input directly into the inverter can run loads and charge batteries.

So, the answer you seek is hybrid all the way and just toss out the SMA inverters.

 

[Quattrohead]

Permits and inspections or not?

 

[captcarib]

Ah. This is up my ally.

I ran an Outback Radian 8048A for 8 years. Outback is grade A top notch and mostly worry free. However, it is not NEMA 3R, so indoor (garage plus) installation only. Also, the Radian by itself doesn't function. You need to purchase and Outback Mate, Hub and if charging from solar, some type of charge controller, which the Outback Flexmax controllers are the best. Since you currently do not have any microinverters, then AC coupling would not be a cost or time saver for you. And remember, your current string inverters are using high voltage input and Outback charger controllers are limited to lower voltages than other brands. This means your panels will have to be rewired into proper serial/parallel combinations with a new combiner box installation and breakers, fuses, etc. That's a lot of labor and cost. Outback Radian also has no closed loop battery support. If installing lithium batteries, then Simpliphi and Pytes play nice with Outback. Once your Outback ecosystem is in place, the system is programmed via the Mate interface of by the website.

Now that that part has been answered, I think your best move it to remove the SMA inverters (they have very little value) and install a Hybrid inverter. Hybrid inverters can accept a DC input to about 500 volts. this will mean connections from the current strings of panels will be much simpler to achieve. I think the best choices are Sol-Ark, EG4/Luxpower and now probably Midnite solar. I say this because Sol-Ark is pretty good at being a dependable inverter from the build point and offers very good technical support and lastly the programmable software, IMO is the best. Midnite solar is a company in the PV business for many years, still answers the phone and is known for making many quality products that last. EG4/Luxpower offers great value and pretty solid hardware at a lower price point than Sol-Ark, but I think their software and tech support is a little behind.

SMA is now offering new hybrid inverters at excellent price points. They do not have a fan for cooling, it is all convection and heat sink. They are space saving, easy to install, priced well and fully featured. To me, their biggest limitation now is using high voltage lithium battery inputs and only can be used with the BYD battery stacks. BYD is top notch.

All of these hybrid inverters offer 240V split phase and can have their output be wired directly into your main panel. They will then provide backup power if the grid goes out to the main panel only if you have transfer switch between the grid input and the main panel/inverter so the grid cannot be backfed by the inverter when the grid is out. I'm not certain if this is up to code though. Consult an electrician.

Also, all of these inverters, except SMA Hybrid, use low voltage batteries offering a great deal of capacity and also closed loop control which is essentially plug and play like a USB port on a computer.

And generator input directly into the inverter can run loads and charge batteries.

So, the answer you seek is hybrid all the way and just toss out the SMA inverters.

Thanks for you advice, I am staying away from HF Inverters bc our Utility company (WAPA) is horrible and constantly spiking voltages with brownouts and lots of unstable grid power fluctuations. The HF inverters rely too much on capacitors and digital software which concerns me if WAPA fries a circuit board that is a major concern. Also their ability to start inductive loads like my well pump, pool pump, and split AC systems. Therefore, I am leaning towards LF hybrid inverters like Outback Radians, Schneider XWPro, etc. Being down here in the Virgin islands reliabilility is a key factor bc getting replacement parts/hardware is difficult and expensive too boot. I also am wary of getting stuck in a company's ecosystem where I can only use their batteries with their inverter etc which I feel is not wise. I am hesitant to scrap the Pool cabana Sunnboy bc I literally installed it only a year ago. LOL

 

[wpns]

I threw away a couple of grid-tie inverters in less than a year because my PoCo changed their Net Metering rules, and I've never been happier. See my profile picture for the details, but two EG4 18Kpv inverters, six EG4 Powerpro Outdoor WallMount batteries, and a couple of ChargeVerters, and I'm essentially off-grid, with the ability to buy grid power without worrying about the power quality.

 

[captcarib]

Permits and inspections or not?

Permit is already in place for net metering grid tie system and i doubt anyone will do a follow up inspection down the road they are lazy AF down here in the USVI. LOL

 

[glandpuck]

Okay, you make some good points. Just remember that Outback power Radian runs warm, but doesn't shut down, it just degrades the power output over 77 degrees. I have run it in the shade at ambient 110 and it didn't shut down. I tried cooling it with a fan blowing on it and also a small 5K btu portable window AC unit blowing on it. That kept it very close to room temperature and the AC used about 500 watt draw. That will maximize life expectancy.

If you go with Outback Radian, I cannot stress enough to also purchase the pre-wired GSLC for your power that is pre wired with all the breakers. This is a big, big timesaver and well worth the money in the resulting clean install.

Keep all the iron Outback except batteries so they all talk to each other via the web.

Also, I like Pytes batteries because they feature all the settings for Outback Flexmax and Radian chargers and are of high quality, good price and available USA based tech support.