Radian vs GTFX

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billvon
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Location: san diego

Radian vs GTFX

Post by billvon » Sat Nov 02, 2013 8:25 am

Question for all:

I currently have a 10kW DC grid tied solar power system. It uses two fairly old Sunpower transformer based inverters (a 3500 and a 5200 watt) fed with three strings from the array. Average operating voltages are around 370 volts for all three strings.

I would like to add an AC-coupled hybrid inverter to this system for a few reasons.

1) I'd like to do some experimenting with smart grid applications, specifically peak shaving and load shifting.

2) I'd like some battery backup for grid outages, although where I am located (San Diego) this is very rare. I think we've had maybe ten outages in the past 20 years.

My plan is to relocate almost all my loads to an essentials panel (basically everything except dryer/AC/pool) use an inverter to service the essentials panel and retain the two GT inverters. Max load without those should be around 5kW. Based on the Outback white paper on AC coupling, I am assuming I will need either one or two relays or remotely operated breakers to shed the GT inverters when operating standalone and batteries are close to fully charged.

DC voltage will be 48 volts.

For this application, would people recommend a dual GTFX/GTVX based system or a Radian? I'd be looking primarily for flexibility and configurability.
--bill von

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MyEnergyWarehouse
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My RE system: Radian Inverter, Mate 3, FM 80
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Re: Radian vs GTFX

Post by MyEnergyWarehouse » Thu Nov 14, 2013 9:21 am

There are various opinions afloat and I present my idea as an opinion only. I think that the Radian has more flexibility and will give you room to grow if needed. OutBack also has a load center that is prewired with the relays to shed the load when grid out and the batteries are fully charged. The Mate3 would give you the ability to do some experimenting with smart grid applications, specifically peak shaving and load shifting.

FYI, when doing an AC coupled system, the inverter needs to be 10-20% larger than the AC load coming in. Would it be possible to AC couple one of your existing inverters? This would allow you to accomplish your goals.

billvon
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Posts: 66
Joined: Tue Sep 24, 2002 11:01 pm
Location: san diego

Re: Radian vs GTFX

Post by billvon » Tue Nov 19, 2013 1:31 pm

MyEnergyWarehouse wrote:There are various opinions afloat and I present my idea as an opinion only. I think that the Radian has more flexibility and will give you room to grow if needed. OutBack also has a load center that is prewired with the relays to shed the load when grid out and the batteries are fully charged. The Mate3 would give you the ability to do some experimenting with smart grid applications, specifically peak shaving and load shifting.
Thanks for the advice!
FYI, when doing an AC coupled system, the inverter needs to be 10-20% larger than the AC load coming in. Would it be possible to AC couple one of your existing inverters? This would allow you to accomplish your goals.
Perhaps. Another option is to implement a faster shutdown option where one of the GT inverters gets dropped instantly when AC voltage limits are exceeded. (They should do this anyway, but forcing one device to do it first may make the system more predictable.)
--bill von

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