NO way this is UL1741 approved ... it claims "Field adjustable voltage and frequency limits " which I am 100% certain UL doesn't allow

You can get a used suntie for 50 cent/watt (Ebay) which can then be upgraded for free. You will end up with a warrented , UL1741 inverter for your 50 cents a watt target ...

Quote from the MicroSine Owner's Manual on the TraceEngineering website:

"This product is manufactured by NKF Kabel for Trace Engineering. The MicroSineâ„¢ inverter is UL listed to the UL Standard 1741 (Draft), Static Inverters and Charge Controllers for use in Photovoltaic Power Systems. It is listed for use either separately from the photovoltaic modules or as a listed component for factory ***embly into an AC photovoltaic module / inverter system. Consult local authorities as to national and/or local electric codes and any additional installation requirements."

I don't know if it should have been listed, but Trace documentation claims that it is. There may be differences between the OK4 and the MicroSine that are required for regulatory approval in the US. It wouldn't surprise me if the current OK4 distribution is using the Trace UL listing, which may no longer be valid.

Regardless of the current regulatory situation, the MicroSine/OK4 is a very effective device. It's primary problem is the cost per watt, which clearly limits it's market potential. The OK5 corrects this problem and should be competitive in the current grid-tie inverter market. The claimed potential is that they can cut the retail price in half, while maintaining a 20 year design life.

It's great to hear that you are optimistic about the upgraded ST. I look forward to your performance report on it.

Rob,

I dug thru the manufactures web site and if you dig deep enough you will find almost ALL of the production is used in the Netherlands

Only for the year 1998 were any units offered for sale to the US , which makes sense since that would have been the draft of UL1741.

This unit is not UL1741 approved and is NOT for use in the US. I will work with Xantrex to see what can been done about this since this is clearly not something that people should be using. The website that one can buy from is not allowing returns so folks ... DONT BUY THESE DEVICES.

On the OK5 , this will never fly in the US , they are using peircing of the AC lines for connecting the inverters , this won't meet NEC requirements and you can't have unprotected 120 VAC running on the backside of the panels , this would require conduit.

This outfit is making inverters for there country and thats fine but don't be lulled into thinking it will be here or legal in the US.

Sorry If I'm comming across as a hard-*** on this one but folks , saftey is a real issue and it not just your *** that's on the line , it's our industry as well.

Thank you for your comments and this is what I had hoped solar-guppy could do , have real questions about real products and get real answers

The history of the MicroSine is that Trace sold it, and claimed UL 1741 certification. I tend to believe that they legally offered it for sale, and that all units sold were (and are) legal to use according to the UL 1741 requirements at the time of initial sale. From what you say, NEC compliance would require (at the minimum) addition of a DC disconnect.

As long as we're quoting rules & regs, I'm rather upset that the ST2500 was placed on the certified equipment list for the California BuyDown program. Xantrex claimed, and some bureaucrat agreed that the ST2500 provides 93% efficiency. You've demonstrated that the 93% is advertising copy, not measurable performance. That 93% figure is used in calculating the amount of money the state rebates for the inverter, so it seems to me that it a legally important number. Who is watching the store?


Shifting gears...

There are currently three general designs for grid-tie inverters. The ST uses multiple strings of groups of 4 solar modules for a 48 volt nominal system. The SunnyBoy uses fewer strings for a up to 600 volt system. The OK5 is a small inverter that supports a maximum of 4 panels.

These design differences impact the final performance of an otherwise identical system. The SunnyBoy design would seem to be potentially the most efficient, since there is no need for a conversion step between 48 (actually more like 65) volts up to whatever is required (300?) to supply the grid at 240 volts. While it is more efficient than the ST design, it is also more dangerous and less fault tolerant. The OK4/OK5 design is attractive because it can be scaled in much smaller increments. If you have multiple orientations (a mixture of south, east & west facing panels), the OK4/OK5 design allows MPPT optimization at each orientation. A single large inverter simply cannot optimize a multiple orientation setup - it is going to be a compromise.

The regulatory problems of the OK5 represent minor design adaptations compared to the technical problem Xantrex has had with design of a decent MPPT implementation. From what I can tell, the OK5 needs a different mechanical connection to the house wiring. AC and DC disconnects are needed. I didn't notice if they have ground fault equipment. And the anti-islanding adjustments may need to be restricted to meet UL 1741. They clearly have the US as a target market, otherwise why include support for 120 volt 60 cycle power?

Xantrex got blind sided by ignoring SMA as a potential competitor. They should have collected competitive performance data on the SMA line long before they finalized the ST design. The OK5 represents another significant design that could cause them real trouble if it got proper localization and marketing. The OK5 offers a superior solution for installations with either just a few panels, or with panels at a variety of orientations.

Xantrex provides a 2 year warrantee for the ST/STXR, with an optional upgrade to 5 years. SMA provides a 5 year warrantee. NKF is talking about an expected 20 year life for the OK5 design. Outback is really proud of the durability of their design. After the MPPT fiasco is past, the next competitive issue will be durability, and the ST isn't exactly a leader in that department either.

I'll know more about the OK4 in a few days , I've ask both Xantrex and SMA to look into this inverter and whether it is legal in the US.

I agree , publishing spec's that are vaporware is not a business like thing [img]images/smiles/icon_eek.gif[/img] and I am working with Xantrex to get things in order and will remind them to get the website spec's corrected

As Far as I'm concerned , the OK5 is just a paper product , it hasn't been field proven and anyone can make claims about how great there latest widget is but without one to test that meets , UL1741 , NEC ,building inspector's requirements and has been independently verified it doesn't mean a thing.

Don't so easily dismiss the cost in both time and money to met US regulations , the costs can run into the 100's of thousands of dollars and if your only going to sell 2000 inverters it doesn't make economic sense.

This year , I am told the entire US market is less than 6,000 inverters ... the only reason SMA got the R&D dollars is due too it was design for the German market and sold 40,000 units. Also The German Market has tougher regulations than the US which makes meeting our regulations a no-brainer. If you notice the OK4 (and OK5) are not sold in Germany.

The ST/XR mess is not directly of Xantrex's making and we can as owners can thank our lucky stars Xantrex is going to make wrong , right.

If this was still trace , they would just look the other way as they did thru 2 years of testing that showed nothing but problems. I've seen the actual test data FSEC and Lakeland Electric pilot programs provided to trace, They told Trace there were serious problems. No one that had anything to do with the ST is working at Xantrex now ....

Xantrex will end up spending millions , on problems that really was the fault of Trace Engineering which Xantrex got thru the acquisition a year and a half ago.

As for voltages you need about 380VDC to make 264 VAC in an inverter , 264 is RMS , not peak , hence when 380 is needed.

There are actually more than 3 choices now that SMA has 3 different models out , the smaller one (I think it is 700 watts) and will work with 4 panels I believe.

They are the same design as the SB2500 , they just use different transformers. Since the power board is the same H-bridge design , they run at the same current , but since the voltage is lower you get the lower power limit.

In two months folks will start being very very happy with there XR performance ...

I am under NDA with Xantrex [img]images/smiles/icon_wink.gif[/img] ....

[img]images/smiles/icon_smile.gif[/img]

[ October 07, 2002: Message edited by: Solar Guppy ]

I've Talked with Both Xantrex and SMA about the OK4U inverter

Xantrex Stated that when UL1741 was approved they dropped the line since it DOESNT MEET UL1741 , I have asked Xantrex remove all references to the product so people cannot be miss led by these sleazy web folks selling non-regulatory approved devices

SMA has forwarded the information on the web-site selling the OK4U to UL which has a department dedicated to shutting down sales of products that claim UL approval when in fact they are not.

SO is it offical , this should NOT BE SOLD or USED in the US ... no if's but's about it

Great! 'Nuf said... [img]images/smiles/icon_wink.gif[/img]

I look forward to the Xantrex update release and favorable results from folks who own the units.

-Roger