But there are advantages to a 48 Volt inverter too.

-More shade tolerant
-Easier to expand......the panels don't have to match except in each string.
-Handles multiple orientation arrays on same inverter better.
-Same array can be switched to a battery inverter easily.
-Part of the array can be split to other inverters without totally disabling the inverter.
-Wiring errors or panel failures easier to diagnose.

One thing that I really do like about the GT is it's 3:1 MPPT voltage range.

String vs Low Voltage is VHS vs Betamax ...

Low Voltage is technically better for the reasons pointed out but the days of low voltage are comming to an end for Gridtie and not to far behind offgrid for the array side as well.

String has won , the reason is it easier , cheaper and quicker to install strings with MC connectors , than conduit and 6 awg wire necessary for proper low voltage systems

I've built both systems , my pool array went up in half a day using my gutter clip mounts , I for one won't be doing Low voltage again , takes to long , but the system size can't start out less than about 1kW for string

Solar is becomming more mature and small technical differences has less influance when compared to the ease of installing , which lowers the total cost. The fact is we are coming from the era from do it yourself types to commerical dealers , which is a needed step for solar to become main stream

The GT is NOT just another grid tie inverter. It was designed by people with phd's in power electronics , went thru extensive accelerated life testing , meets all conceviable regulatory testing and gets my seal of approval , which took 5 months of testing with a VERY critical eye for the smallest of details to be resolved

Xantrex is a 100 million dollar power electonics company , this is THEIR design , not a buyout inherited design. I know the inards of the GT well and there in nothing on the market with this level of fit ,finish and quaility designed in

There is much more in store for the comming year in new products , a very exciting time for the solar PV market

I feel both technologies are viable and each has their own benefits/disadvantages. I predict that 12/24/48V systems will be around for a long time to come. Telco has had -48V for decades. Marine and RV also are applications that do not have the space to benefit from HV DC designs.

The design of the GT-3.0 is clearly driven by market need. Xantrex did their homework and designed a unit that is quite competitive. It is clearly better than the SunnyBoy and PVPowered, however the Fronius is almost identical in features/design. I'm looking forward to a Xanbus version of fishbowl.

Just because a design is inherited does not necessarily make it bad. Many tech companies are bought simply for their design work. In some cases a startup may have the flexibility that a larger company with shareholders does not have. Hopefully vendors will see that it takes all kinds and not try to simply their product lines down to a one size fits all mentality.

Given all that, had it fit my application I would have chosen either the GT-3.0 or the IG3000. But my application has kept the SunTie as the preferred option.

Sean

Oh yes , and I aggree , what I suggesting is that the array side to charge controller will go string as well , battery side will be 12/24/48 for much longer



Wish Granted ... it's called GT-View but uses the RS232 port. Xantrex didn't think the name "FishBowl" was the best choice for the product name



No , but they take the heat when it is , unfairly as they had no part in it's design. All problems come down to design decisions and directly reflect the choices that company made




The Suntie still has it's place , Xantrex is looking to discontinue it but there getting more order than they know what to do at the moment .. as we have discussed , low voltage has many advantages and for smal and or to be expanded systems , they is no other choice. Time will tell when production is actually halted , but I feel it will live on longer than the product marketing folks had planned

As for the IG2000/IG3000 , it is not in the same class as the Sunnyboy or GT ... what Fronius doesn't openly discuss is it has 3 operating ranges , and each take about a 1% hit in efficiency , you can actually hear a relay click when you cross the voltage threshold from one range to the next and I thought I was nuts as I watched the efficiency drop a full percent on the power analyzer. To there credit , I explained my finding to Fronuis US and they were VERY open in discussing their units performance.

On the Fronuis , it 150 to 210 , 210 to 270 , 270 450 as the ranges

Efficiency is 91.5 , 92.5 and 93.5 for the above peak. As you can see , the Suntie will actually match performance in the first range and with string inefficiencys ... even the high voltage modes , the Suntie will be a close tie in harvest

For the Record , PVPower is a peak of 93.2% (220 vdc (with a host of software odditys further lowering harvest) , the Fronuis is 93.7% when running at just over 270 VDC , Sunnyboy peaks at 94.5% at 230 VDC (very bottom of opeartional range) and the GT is 95.2% at 220 VDC

The GT holds above 94% to about 2700 watts (all the other inverters tail off signifigantly) and with hits huge heat sink and high efficiency , even at large power loads , really kicks butt on daily harvest.

Will GT-View collect data from a SunTie? If not will you release an update to fishbowl? Visually I find GT-View to be more attractive than fishbowl.

Scability wise one RS-232 port/inverter is not practical. I read that Harvard installed 16 SB2500s in one building. Even at 8 ports/PC that is still two PCs simply for monitoring. Also GT-View really needs to install as a service so it will run without having to log in.

Have you considered RS-485 and having the inverter send an ID number in the header? At 36bytes/inverter/sec and 9600bit/s you should easily be able to fit 16 inverters per port.

Sean

Well, practicality has triumped over idealism. I just shipped back my three STXRs and have three GT 3.0s enroute. Overall I'm saving ~$2K on wiring, conduit and other costs.

To wire 16 Sanyo 190W panels to a STXR would have required six runs of #6 in 1 1/2" or 2" conduit, replacing the MC connectors and fuses at every panel to meet NEC codes. An equivalent design with a GT 3.0 is two runs of #10 in a 1/2" conduit using the existing MC connectors.

Couple questions about the GTs if anyone can answer them:

1. Are there any commands you can send to a GT over RS232 besides setting display labels and shutdown?

2. Has anyone taken a look at the XANbus (CANbus) data format for logging purposes?

3. Does the GT spit out the same 36 byte data structure every second like the SunTie?

Sean

The GT uses plane text ascii for commands ... hooking up a rs232 monitor and you'll quickly see what commands GT-View is sending ...

Everything is query based on the GT , so yes , there are about 30 commands but I don't know what Xantrex is going to have for public documentation

I wrote GT-View for full logging and it also does system values , there is nothing being passed on the X(c)anbus that GT-View doesn't already report , just cat5 the units together (standard enet cables) and you'll have fully system values reported (option in GT-View)

The Suntie Data structure is raw binary , it has nothing in common with the GT communications

Speacock , please update you email in your profile ,everytime you do a post I get a error message that your email bounces (you have notify me on posts/responses) or don't use the notify me option

If you want to see what GT-View can do on a multi-inverter installation , check out my real-time status ...

www.solar-guppy.com , click on real-time status

Got one inverter up. Waiting for first light... The other two are on backorder.

Couple of comments:

- The mounting bracket is nice, however the 15.9" wide inverter is too narrow to mount between 16" studs without a plywood backing.
- The beige blends in better on my wall than other product colors
- The string combiner is for two strings only. If possible I'd love to see a larger option.

If I were to go external string combiner, would four strings of six (~320Vdc) or three strings of eight (~420Vdc) be better? Is there any efficiency difference based upon DC voltage?


Sean

No , you use the Center mounting holes , thats why it's 16" on center



Lower is better , efficiency wise for the inverter

Two strings works well when using large panels (150watt) which is what most new installs are doing.