Radian vs GTFX

bill von novak

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.

For backup I have an older Trace SW4024 that backfeeds through a separate breaker on the panel. (I use an interlock kit to prevent the main breaker and the inverter breaker from being turned on at the same time.) I keep it charged via AC and have a Honda EU2000i for longer outages. So far I have used it a grand total of once for about 8 hours since power around here is fairly reliable. Using it is a very manual process involving much reconnection and flipping of breakers.

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 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.
3) My current backup system is a total kluge.

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 Sunpower GT inverters. Max load without those should be around 5kW, with average loads of around 500-1000 watts. 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.

Based on my past experience with inverters I think I'd go for Outback over any other inverter supplier. For this application, would people recommend a dual GTFX/GTVX based system or a Radian? I'd be looking primarily for flexibility and configurability.

Cariboocoot

Re: Radian vs GTFX

This might help you decide:

One GVFX3648 3600 Watts @ 120 VAC $1,800
One Radian 8048 8000 Watts @ 240 VAC $4,000

Essentially the Radian is 4X the GVFX.