I was thinking out loud of 3kw, as the voltage goes up the inductor has to increase accordingly, so while yes in theory you can get 8kw+, that wasn't my thought

All charger controllers are this way, the MX-60 is about 3kw, so you can't run it 60 amps at 70 volts for example.

The more functions in one box, the harder it is to make the product. Having a stand-alone DC converter has the appeal IMHO of just being a replacement for wires and switches... nothing more, and with copper costs, it could easily be 1-2K in wire and proper DC-switchings to re-create what I do in my garage

Efficiency would be pretty good, the GT5.0's input stage is about 25 amps for a 200-600V range and I believe its about ~98% efficient... thats still 100 watts of heat to deal with!

Now wether the market is big enough to fund the 7 figures to design, test, certify to UL/FCC a product is something a marketing guru would have to tell you ....

You could make this as an uncertified kit. Make it robust, make it safe, make a profit. This would not be a 24/7 item.
I would drag it out of it's box after the earthquake, yank the wires off the GT, and connect up my SGT Universal DC to 48V converter, attach my 330VDC PV array, and charge up the 4 Costco deepcycle batteries I've stored. When the batteries are full, I'll fire up my 48V - 120VAC inverter ( I know someone makes one! ) and run my fridge and freezer till nightfall, then use 2 CFL's to keep the house lit ( and attract looters ! )
When the grid comes back in a week or so, then I have to un-hook it all, but I'll have lived more comfortably that week.

unit blows up due to user abuse , starts fire an burns down house ... insurance company doesn't pay because the black box is not UL listed, owner sues "manufacture"

If your in a desperate need of power, no charge controller is needed, just hook the solar ( even potenional 300 vdc ) directly to the battery. Solar will run at the battery voltage until charged .. have to watch manually, but you will get some watts

It might only be a 100 watt charge from the 2kw array, but it will work just fine.

"Uncertified" commercial product--nobody, outside of China, would touch that with a 10 foot pole.

How about approaching the "cost" from a different angle... The 4:1 converter would have "roughly" the nominal current/power rating of a Xx-60 and 1/2 the price of the Xx-60.

Or reduce the current/power rating to achieve 1/2 of the Xx-60 price--and what would the 4:1 ratings be like?

Somebody already thinking of adding a Xx-60 controller and battery bank (and probably inverter too) to an existing GT populated Grid-Tie System, would not have a heart attack at that 4:1 price point (1/2 the MPPT charge controller cost). And it would get the vendor the sale of a Xx-60 and probably a sine wave inverter/charger/AC Transfer Switch too.

Just out of curiosity, would the system be stable if there was a GT inverter plus 4:1 converter + MPPT DC Charge Controller when attached to the same solar panels? Or would there need to be a cut over / transfer switch function (GT or 4:1. Sense current/function of GT Grid Tie with 4:1 and only switch on 4:1 when GT current/operation is off)...

-Bill

PS: At $300, it would be "cheaper" for me to buy the 4:1 than to hire an electrician with a ladder to rewire my existing solar panels and install the Low Voltage transfer system.

1) It's an Educational Kit. does not need certification. I'd buy one if it looked robust enough.

2) At $600, it's cheaper than getting an electrician the day after a earthquake or something takes the grid down. Pull out the box, hook up wires and all done. 1 hour, standing on the floor of the garage (if the garage is still standing)

I thought the solar was in the rental house ? ... your tenants going to be evicted after "the big one"

Whatever it takes. The place is huge, they'd be glad to let me camp out on the living room floor, if they have power for their laptops and fridge ! Civil Emergency and all..

If the garage roof is "on the ground"--no sweat rewiring the panels for the WX-60. Right?

-Bill

I looked into this and found the Sunny Island. It will create an 'island grid' that the Sunny Boys can sync with and supply power. It will communicate with the Sunny Boys and throttle them down if there is not enough load. It is expensive and requires batteries.

I was wondering if Xantrex had plans for such a product, but no reply to my inquirey on their forum. I too decided that for 1 week a year power outages, it is better to just run an economical generator.

I emailed them, they also have them on Ebay at a good price.

Fred