Ok, what are the chances that Xantrex can install this bypass feature on their newest Inverters, Something that will allow a 12 volt battery to fired up the Inverter with safe disconnects to the Grid? Do you think its a liability issue on their part? Life would be good if this was the case.




Fred

I don't understand your question, what is "bypass mode"

As for changing how a UL1741 inverter works, 100%, Xantrex isn't changing the design or any other manufacture of a gridtie unit or that matter.

Wishing it so, doesn't make it so ....

Currently the Inverters sense a voltage from the Grid, once this voltage is dead, the inverters shutdown as a safety feature.

At this point, It would be nice to have the Inverter switch to 12 Volt battery input power when the grid crashes so that it can stay online and operate internally off the Grid.

Im sure that Xantrex can build a 12 volt sensor in the inverter to keep the inverters up and running. Once the outside breakers to the grid are turned off, the 12 volt battery will kick in and operate the inverters.

So instead of it looking for high voltage, they can install a low voltage regulator or transistor to handle the switch.

In a real world this is how I like to see it work.

But like you mentioned, Clouds etc will cause problems

Fred

I really still think that getting a good generator (like the Honda eu2000i) is such a good deal... Say instead you wanted to store 10 kWhrs of electricity (not even quite 2 gallons of fuel for the Honda).

http://store.solar-electric.com/cosuagmba.html

A Sun Xtender PVX-1040T AGM Sealed Battery; 104 Amp Hour, 12 Volt; is $252.63...

12v * 104 amphr * 0.80 discharge = 998 kWhr

Or, you would want to have about 10 batteries or $2,526 worth of batteries (plus wiring, plus A/C grid charger, plus inverter, plus solar charger) to store the amount of power of 2 gallons of gasoline.

Sure, I can go longer than 2 gallons of gas with this setup--but I can also store 20 gallons of gas plus another 20-40 gallons of gas from my car/pickup... I can go 10-20 days with the generator and 40 gallons of gas for $1,100 or so... The solar solution would cost me well north of $3,000 plus a battery shed, plus hoping that the solar panels were not damaged in a storm, or earthquake, or that I did not need the system in winter when I get about 1/5 the normal sunny weather power (and I still have to replace the batteries every 5-10 years vs I just reuse the old gas and replace it with new one per year).

The above, is why I decide on a Grid Tied system plus generator rather than a hybrid on/off-grid system.

-Bill

But, it is not just keeping the electronics alive with 12 volt DC... It is the way the inverter regulates power. Current regulation based on solar input power available is exactly 180 degrees different than voltage regulation base on output voltage (and frequency/phase).

The Grid Tie inverter just follows the Grid voltage/frequency and assist by adding power. An off-grid inverter regulates the voltage and frequency and just supplies current as required by the load.

Certainly it can be done (someway)--but it is not going cheap or easy to "convert" a design.

-Bill

Thanks, I understand where youre coming from.


Fred

As a follow up, the GirdTie inverters don't wait for zero volts, there is a narrow window in voltage and frequency that is allowed by the UL spec.

Its ~264-211vac , +- 0.5hz ... doesn't take much to trip a unit offline and why the almost never will sync to a generator.

And there are units that do automatic transfer as you want, a Xantrex SW4048 or a Outback GTFX3048 ... but ANY inverter that will be a stand alone unit need battery storage on the input. So the Solar -> Battery is handled by a seperate unit called a charge controller.

As for the fuel thing, generators pig thru gas, 2 years ago in Florida when I had 4 hurricanes pass in 2 months, there were lines 8 hours long of people TRYING to get gas. Now a propane genny would make sense, but since I HAVE the panels, my addtional cost is just the Charger and Inverter ( about 1600.00 as I designed the charger and got it for "free" ). Battery bank was 1200.00 for 205 ah AGM's at battery USA, which just happens to be based in Lakeland 10 kWhr of storage

For this cost, lets say 4K, I have unlimited generation ablility while other are panic for gas ... and I have seen it more than once, and once is enough to know who gives a sh&t what it costs, I'M NOT going to be one of the people inline!

Hence the the constant refrain of "when can we get a 200-600 VDC simple, reasonable cost, don't care too much about the efficiency or extra function battery charger as a mate to the Xantrex GT family inverters"...

It would even be cool if the Xantrex GT could have an alternative DC output in the 50-125 VDC range so that an off-the-shelf MPPT charge controller could be used for emergencies.

-Bill

OK, I'll bite. Lets say SGT makes your dream box, its a black box that is parrallel to the GT's PV inputs, it reduces the PV voltage by 4 to 1 and similary boost the current so an off the shelf MX/SC/WX-60 can do its job

Whats the price in efficiency you'll tolerate and what's the market cost one would pony up to buy one? what do you expect its amps/watts can handle ?

Assume that there is a reason that 60 amps (or so) output is picked for a reason in Brand Other charge controllers...

4:1 voltage drop / 1:4 current...

200-550 vdc working voltage input

200vdc/4 * 60 amp output = 50 vdc * 60a = 3kW
550vdc/4 * 60 amp output = 137.5 vdc * 60a = 8.25 kW

Then there is my system running at ~300-320 VDC peak (of course, we all know that "my" system is the average system out there and the new product should work perfect with "my" system.

320/4 * 60 amp = 80 vdc * 60a = 4.8 kW

My system is an ~3 kW STC system, so 60 amp is way over the available power... perhaps even cutting this to 30 amp maximum output would be perfectly OK (assuming that people with larger arrays could parallel 4:1 converters).

We look at a "Brand Other" Mx-60 runs around $500-$650 each.

That is approaching ~$1.00 per watt at 12 vdc (assuming I remember everything correctly in that this is 60 amp * 12 vdc = 720 watts), but only ~$0.25 per watt for a 48 vdc battery bank. Obviously, when first introduced can charge more than as the product gets more competition.

Since the output power is highly dependent on the input voltage--picking a price point like $1.00 list, and $0.50 wholesale/volume buys does not make sense...

And looking at the pricing for the Mx-60... Pick 24 vdc battery bank. 24v*60=1,440 watts. Makes list price around $0.50 per watt. The solar panels are ~$5.00 per watt, so the "piece of equipment" is around 10% of the panel price.

Going back to my 320 volt / 4 @ 30 amps--that would be 2,400 watts or $12,000 list for panels. 10% of that would be $1,200 or $0.50 per watt...

$1,200---I would guess would be the high end price for a 30 amp output unit... Perhaps a smaller sized 4:1 converter unit, say 15 amps @ $600, would be a better price point for entry level converter.

The Honda eu2000i (1,600 Watt continuous rating) Internet price is around $900 (or a bit less) delivered. $1,200 for 2,400 Watts using solar power that would otherwise be wasted seems like a good price point.

Now, the prices I listed above are assuming a minimum function stand-a-lone unit. But, because it does something that nothing else does--I would think it could get some attention in the market. If it could be listed for 1/2 of the above price--(say 1/2 the price of a Mx-60 controller)--it would become very interesting to many more folks.

Now, whether this unit should be a stand-a-lone unit or combined as an optional input module for a Xantrex Solar Charge controller--something that marketing could work out.

Also, I gave the above as a maximum price, I would guess, the market will support for a one-of-a-kind product. If the manufactured price supports a lower list price--combining with other functions (such as a full fledged MPPT charge controller) may help keep margins up and lock the market to the one SGT unit.

Now, efficiency... 1st assumption is that this is a double conversion unit for emergency use--so that 0.93*0.93=86% is a guess at the approximate "best" efficiency one could get from this unit. It is possible that cost of copper wiring and the fact that I squared R wiring losses would be 1/16 of a low voltage controller may help some folks that have to place panels in the sun quite a distance from point of use.

If the list price is kept low, and this is assumed to be a generator replacement (auto-switch would be nice--may have to sync with GT LINK?), efficiency is not going to be the big seller...

And, as a "standby" battery charging system, if the efficiency is much less than 85%, then simply using a 120/240 VAC charger for battery maintenance (and maybe charging with that cheap emergency gas generator) would be more efficient anyway.

But, have to be careful of the added costs (Converter, Solar Charge Controller, possible AC Mains Battery Charger, possible backup-backup fuel driving generator)...

I will stop typing here... Anything of interest yet?

-Bill