Feeding Outback PS-1 for Aux Charging

System · February 2010

Hi all ...

We're just digging out after a big snow (no surprises there), and due to the location of our PV's, had to rely 100% on battery during a power loss.

It was disappointing ... our time to exhaustion was about 24 hours, with nothing coming in from the PV's.

The system is a grid-tied with battery backup, centered on an Outback PS-1 Grid tie (packages an FX inverter and MX charge controller together), two PV arrays and as much battery backup as space permits, wired in series/parallel as a 48V system.

I'm looking at physical systems to clear the PV's of snow, but see little encouraging ... the location is too dangerous to use rakes, and the heat tape suggestions seem too weak to handle any real snow.

So I'm thinking about ways to boost the battery charge in emergency situations.

While I understand that bike-powered generators aren't much help in a steady state, I wonder if they might be just the thing to keep a 48V battery array alive during a limited duration emergency event. The problem comes in making good use of the Outback PS1.

The PS-1 is equipped to accept a generator input, but that's on the AC side, and for safety and environmental reasons we don't want to get a gasoline generator.

The human-power systems we see typically put out 12V. I'm leery of wiring up a secondary charge circuit when the PS-1 is all set to handle battery charging and any secondary work might mess it up.

Is anybody aware of:

1. Safe and creative ways to use the PS-1 as a charger by supplying 12-20VDC
2. Human powered generators that put out something like 12oVAC to feed the PS-1
3. Maybe one more PV in a vertical location or somewhere easy to scrape, just to handle charging in the snow
3. Better ideas than I've come up with?

Thanks,

Robin

mike95490 · February 2010

Re: Feeding Outback PS-1 for Aux Charging

Forget about using a human power bicycle generator, pro athletes can surge to 75 or 100 watts, but mortals can deliver about 50 W max.
What's your battery AH ?
Did you reduce ANY usage in the emergency?
A small gas generator IS your only hope, or you can sit in the cold dark.
Connect your Prius as a UPS, and use it's battery.
http://www.priups.com/exec-summary.htm

BB. · February 2010

Re: Feeding Outback PS-1 for Aux Charging

If you don't want gasoline genset--your "safer" alternatives are, natural gas, propane and diesel...

For random power outages--propane is a great fuel to store--and many homes have a propane tank for cooking/heating.

The biggest issue with any emergency/off grid solution is usually a big old inverter with limited battery and alternate power supply (solar, genset, etc.).

If you have the "3000" package--basically a 3kW inverter and a 4kW emergency battery pack... If you assume that you can use 3kW of electricity (all of the normal house hold loads)--you would drain the system in about 1 hour.

For you--:

4,000 Watt*Hours / 24 hours use = 167 watt average load

That is not much power--A refrigerator, a few lights, TV/Radio, and perhaps a little central heating (using gas or oil). That is not a lot of power.

A Honda eu2000i running on gasoline would supply almost 2x the average power for 15 hours straight on 1.1 gallons of gasoline. (15 hours, 400 watts load, 1.1 gallons of fuel). There are some propane conversions for the Honda's or there are some bi and tri fuel Yamaha gensets too (gasoline, natural gas, propane).

In reality--any reasonably sized solar array based off-grid/backup power system will still need either a back up genset, or the owners will simply have to dramatically ration power if there is no sun (and/or not many solar panels).

If your system is in a Condo / Apartment -- Gensets are typically really difficult to use.

One person here got a couple AGM's that they could carry/wheel to the complex's community center where they had backup generators--and would allow him to plug in his batteries to recharge when needed during an outage.

-Bill

System2 · February 2010

Re: Feeding Outback PS-1 for Aux Charging

Yes, we certainly cut back on power use to the minimum. Which means essentially a refrigerator, heat (gas but electric fan) and maybe the odd electric kettle for a pot of tea.

We got 24h, as stated.

Next time (probably tomorrow the way it's shaping up, we'll cut out the heating and the kettle which I expect are the big drains. Brrr.

It's a pity the bike solution can't provide enough to power the array, but that does seem to be the consensus opinion.

I wonder though ... what about one more PV panel mounted vertically on a (winter sun facing) South wall. It just might provide enough power in the day to drag out the battery life for a couple more days. Anybody got the equations per hand ... is it a straight matter of watt-hours (of sun) in +/- watt-hours draw on the batteries out minus inefficiencies in the system?

And yes, I'll look at propane powered generators, but it is suboptimal. Still, I had no idea the (gasoline) fuel usage was so low. Wonder if propane's similar.

R.

mike95490 · February 2010

Re: Feeding Outback PS-1 for Aux Charging

propane's energy density is less than gasoline (which is less than diesel) so - you will use more. But it's a very safe and easy to store gas, and there are add-on kits for the Honda EU2000 gensets. A 5gal BBQ grill bottle would run a small honda for several days, lightly loaded. You would need to purchase a battery charger, to convert the 120VAC to 48V for charging.

BB. · February 2010

Re: Feeding Outback PS-1 for Aux Charging

Assuming you are somewhere around Washington DC (like to keep us guessing?)--Using PV Watts Website, assume near Baltimore Maryland; 1 kW of panels (smallest program supports--and round number); 0.59 derating (90% efficient AGM batteries, 85% efficient inverter, 77% balance of system eff), fixed mounts:

"Station Identification"
"City:","Baltimore"
"State:","Maryland"
"Lat (deg N):", 39.18
"Long (deg W):", 76.67
"Elev (m): ", 47
"PV System Specifications"
"DC Rating:"," 1.0 kW"
"DC to AC Derate Factor:"," 0.590"
"AC Rating:"," 0.6 kW"
"Array Type: Fixed Tilt"
"Array Tilt:"," 39.2"
"Array Azimuth:","180.0"

"Energy Specifications"
"Cost of Electricity:"," 7.8 cents/kWh"

"Results"
"Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
1, 3.47, 64, 4.99
2, 4.40, 73, 5.69
3, 4.79, 85, 6.63
4, 5.12, 86, 6.71
5, 5.28, 87, 6.79
6, 5.70, 87, 6.79
7, 5.61, 89, 6.94
8, 5.28, 84, 6.55
9, 4.95, 77, 6.01
10, 4.90, 83, 6.47
11, 3.58, 61, 4.76
12, 2.85, 51, 3.98
"Year", 4.66, 928, 72.38

So, for February, 73 kWhrs per month or 73/30=2.4 kWhrs per day per 1,000 watts of panels. If you have 300 watts of panels:

2,400 Watt*Hours * 300 watts/1,000 watts of panels = 720 Watt*Hours
720 Watt*Hours / 167 Watts average load = 4.3 hours of use per sunny Feb. day...

To supply your 4kW "average load" day in February:

4,000 WH / 720 WH per 1,000 Watts of panels = 5,560 Watts of Solar panels

So--I am guessing, that one panel is not going to make much difference on your system.

Regarding propane vs gasoline:

Propane: 91,540 BTU per gallon
Gasoline: 115,000 BTU per gallon
115,000/92,540= 1.24:1

So, propane will require (all things being equal) require approximately 24% more gallons vs gasoline.

If you have a car/truck with gasoline--fill up before storm and get a siphon... You will have 10-17 gallons or so available for the genset.

Regarding how efficient the generator is... I cheated and recommended one of the most efficient generators (and sort of expensive) there is for small wattage 120 VAC power use...

If you got your self the standard 5kW gasoline genset and tried to use it to power a 400 watt load--you would need around 0.5 gallon per hour to supply the same load (7.5 gallons for 15 hours). And they are terribly noisy.

The Honda eiX000i family, you can stand right next to them and hold a conversation. On a busy city street--you cannot even hear them running unless you are standing right next to them.

The Honda eu2000i can be found online for around $900-$1,000 shipped (guessing--it has been years since I purchased mine). That is much more expensive than the el cheapo gensets--but it is so much more fuel efficient fo the smaller loads. If you decided that you wanted to power a 1,600 watt electric heater--then it would run around 4 hours on 1.1 gallons of fuel (0.28 gallons per hour).

Now--if you need 1,500 watts continuous load--it will obviously take a lot more fuel to keep you in power.

In the end, you need to match your loads to the power source.

There are options out there--If you can let us know what your requirements are.

-Bill

BB. · February 2010

Re: Feeding Outback PS-1 for Aux Charging

I believe your Outback PS-1 does contain a 45 amp 48 volt battery charger. I think you can use an "Outback Mate" to program the inverter's internal battery charger for a low charging current (if you use the eu2000i) or you can use a larger genset (eu3000i) -- at the cost of somewhat more fuel usage (gets more complex--you can charge the battery bank quickly, then turn off genset until the battery bank needs recharging again--basically like a Hybrid automobile--can allow a large genset to be "used at low power" -- use the battery bank for low power operation).

I am certainly no expert in the details of the various products out there--download a manual and/or call up your installer for help.

-Bill

System2 · February 2010

Re: Feeding Outback PS-1 for Aux Charging

Thanks for so much help!

Yes, I'm just north of DC by the river, should've said.

The PS-1 does indeed contain a battery charge capability ... that's how we keep the current backup batteries charged. Big point ... I don't need to run live off of the aux source, just charge the batteries up some during the day so that when they do go south it's in 4 or 5 days, not the current 24 hours.

And no way do I need 4KW ... at peak with the heat running my Outback mate said we were drawing 0.9 KW.

All that said, the high end Honda generator does sound like a good choice in straight dollars and cents; $1000 compares favorably to a single panel.

I assume that generators had darn well better be outside unless I like CO poisoning! I wonder ... the wiring to the PS-1 would ordinarily be a pain, and one would usually never connect a generator to AC for fear of frying the utility folk. But my PS-1 is supposed to prevent that. Would it be possible to use an existing electrical outlet to back-feed the generator's power to the system, simulating line voltage, which already charges the batteries?

On another note entirely ...

There's a new micro turbine unit coming out from honeywell:
http://www.ownyourwind.com/.

Would that work well with the PS-1? From what I can see on the Honeywell site, the unit comes with its own inverter, so perhaps it makes sense to treat it as a generator in relation to the PS-1? What do you think? Combining solar and low intensity wind (snow usually comes with some) might just keep those batteries topped up.

BB. · February 2010

Re: Feeding Outback PS-1 for Aux Charging

robinpc wrote: »

The PS-1 does indeed contain a battery charge capability ... that's how we keep the current backup batteries charged. Big point ... I don't need to run live off of the aux source, just charge the batteries up some during the day so that when they do go south it's in 4 or 5 days, not the current 24 hours.

Problem is that 4-5 days is a lot of power -- or a very large standby battery bank.

And no way do I need 4KW ... at peak with the heat running my Outback mate said we were drawing 0.9 KW.

All that said, the high end Honda generator does sound like a good choice in straight dollars and cents; $1000 compares favorably to a single panel.

For emergency backup power--gensets are very good price/performance vs solar+batteries+inverters.

You can use the genset to charge during the day, and run off of batteries at night--that is the classic "Hybrid" generator system. Nothing wrong with that at all--assuming your generator/charger match up in power needs and you have enough fuel.

I assume that generators had darn well better be outside unless I like CO poisoning! I wonder ... the wiring to the PS-1 would ordinarily be a pain, and one would usually never connect a generator to AC for fear of frying the utility folk. But my PS-1 is supposed to prevent that. Would it be possible to use an existing electrical outlet to back-feed the generator's power to the system, simulating line voltage, which already charges the batteries?

I have not looked up the PS-1 internals (what model of Outback Inverter)--but it should have an internal AC transfer switch that will protect utility workers... More or less--it is just a bigger version of the UPS that you use to for computer backup power.

I am not sure what you intended to type when you said:

"Would it be possible to use an existing electrical outlet to back-feed the generator's power to the system, simulating line voltage, which already charges the batteries?"

I want to be very clear and safe for everyone involved... Some Inverter only have an AC power inlet. Others have an AC1 power (for utility grid) and an AC2 (for backup generator connection).

If yours has the AC1 only--then you would need to disconnect from the utility circuit and manually plug that into your genset.

If yours has the AC2 input--then all you should need to to is connect that to your generator. The Inverter/Charger will take care of the rest.

Your Inverter / Charger is a bit large for the eu2000i--unless you can program the charger's current down a bit--should not be difficult--but need to know what inverter you have and possibly if you have an "Outback Mate" interface device (needed to reprogram the charger settings).

I am not an expert here--and I don't know what you have. You may have to contact your installer to get these answers and setup your charging parameters to match the genset.

Difficult to do in the middle of a snow storm...

On another note entirely ...

There's a new micro turbine unit coming out from honeywell:
http://www.ownyourwind.com/.

NOTE: If this was your first post and its only content--you would run the risk of being banned for spamming.

;)

Run away from that wind turbine. It is a scam. There are about 100 issues that their installation would cause problems with.

Would that work well with the PS-1? From what I can see on the Honeywell site, the unit comes with its own inverter, so perhaps it makes sense to treat it as a generator in relation to the PS-1? What do you think? Combining solar and low intensity wind (snow usually comes with some) might just keep those batteries topped up.

For any DC auxiliary charging source... Basically you connect them to the battery bank with their appropriate charge controller.

Shorter answer-I am not a believer in small wind and you will need to do more research before spending $1 towards a small wind system. If you live in a very windy area (trees "flag" from prevailing winds), you have a 1 acre or larger lot, and can put a turbine on top of a 60' plus tall tower and there are no obstructions within 500' of the turbine over 30' tall--perhaps it would be worth looking into wind power.

-Bill "wind rant off" B.

System2 · February 2010

Re: Feeding Outback PS-1 for Aux Charging

I have not looked up the PS-1 internals (what model of Outback Inverter)--but it should have an internal AC transfer switch that will protect utility workers... More or less--it is just a bigger version of the UPS that you use to for computer backup power.

Harder than one would think to figure out the model ... Outback wins the modesty prize with their labeling. It's a GVFX-3648, which must make my thoroughly unlabeled PS1 a PS1-3000.

I am not sure what you intended to type when you said: I want to be very clear and safe for everyone involved... Some Inverter only have an AC power inlet. Others have an AC1 power (for utility grid) and an AC2 (for backup generator connection).

If yours has the AC1 only--then you would need to disconnect from the utility circuit and manually plug that into your genset.

If yours has the AC2 input--then all you should need to to is connect that to your generator. The Inverter/Charger will take care of the rest.

And herein may lie the trouble. I see no signs of an AC2 connection. What's worse, in the documentation for the FX (which is admittedly old, from 2005) it sez (p12)

"The GFX is designed to accept a utility grid quality AC input. Using a GFX with a generator as the AC input is not recommended. Most generators, even high power stable generators have been shown not to connect or charge through the GFX. Outback is working on this problem, but for the time being do not expect your generator to work with the GFX."

Have you heard anything about this problem being fixed since 2005? Perhaps an upgrade or new software is available? If not, looks like generators are out. Obviously I'll ask the Outback folks, but you and the crew here may have had more practical experience. Thanks if you do.

Your Inverter / Charger is a bit large for the eu2000i--unless you can program the charger's current down a bit--should not be difficult--but need to know what inverter you have and possibly if you have an "Outback Mate" interface device (needed to reprogram the charger settings).

Yep, have a Mate. Not the easiest thing to use.

Run away from that wind turbine. It is a scam. There are about 100 issues that their installation would cause problems with.

First, profuse apologies ... no spam intended. I'll not post a URL again.

I am puzzled ... few scams get the kind of mainstream press this puppy has, or the Honeywell name to back it. But I'll certainly approach it with far more caution. Is it that you think this is infeasible poor technology, or that there is a chance it doesn't actually exist? Or if you'd prefer not to talk about it any more, no worries.

I appreciate the trouble you've taken! As for the next snow (tomorrow), I think long underwear is in the forecast.

solarvic · February 2010

Re: Feeding Outback PS-1 for Aux Charging

I am preety new to gridtie. Went online dec.23. All my panels are top of pole mount. I clean off the snow every morning. I went to hardware store and bought a squegee for cleaning windows and mounted on 10 foot piece of condiut for a handle. Works real well. Will give you lots of reach and you can,t get shocked since the conduit is insulated. I had thought of putting rainex like you put on windshields so the snow would slide off. Was told not to put anything on the panels. But they didn,t tell me why. Maybe someone here in the Know can tell me why. Solarvic

BB. · February 2010

Re: Feeding Outback PS-1 for Aux Charging

robinpc wrote: »

First, profuse apologies ... no spam intended. I'll not post a URL again.

I am puzzled ... few scams get the kind of mainstream press this puppy has, or the Honeywell name to back it. But I'll certainly approach it with far more caution. Is it that you think this is infeasible poor technology, or that there is a chance it doesn't actually exist? Or if you'd prefer not to talk about it any more, no worries.

Don't worry--we (Niel, Windsun, and me on occasion) work hard to keep this forum spam free and there are more than a few folks that try and drop a link to something and we never hear from them again.

People who post, interact and ask questions, with links, are never a problem. Notice the smiley faces next to the "warning".

Regarding the Honeywell Wind Turbine, you can find some discussions by clicking this Google Search Link or by typing into Google Search:

honeywell +turbine site:wind-sun.com

The +turbine will make sure it is wind turbine and not generator or other Honeywell products. the "site:wind-sun.com" limits searches to this forum (frequently Google is an easier search tool to use on this forum--short searches tend to return nothing at times).

More than happy to discuss the HWT in detail--but it has been pretty much beaten to death for awhile here (note: I am not very favorable to "small wind"--so take what I say with a grain of salt--like all information from the Internet).

From Wind-Works.org--you can read a review about the Honeywell Wind Turbine.

-Bill

RandomJoe · February 2010

Re: Feeding Outback PS-1 for Aux Charging

The Outback grid-tie inverters are VERY picky about votage and (especially) frequency on the AC input. That's simply by nature, they have to disconnect from the grid pretty quickly to meet the anti-islanding provisions.

What I found when I was contemplating a GTFX is that a generator will work, as long as it is able to maintain frequency and voltage within tight tolerances. The usual problem is when a load is suddenly applied (like the charger in the inverter kicking in, or switching the subpanel loads over to line). That requires either a really beefy standard generator, or an inverter style generator (like the Honda EU series) that can cope better.

Outback still says the GT series isn't intended for generator use, but they do acknowledge that *some* inverter-type generators have been found to work, notably the Hondas.

If you connect a generator this way, you may want to turn off "sell" mode just in case. Not sure what would happen if the sun came out and your inverter tried to push power back toward the generator. Maybe nothing, but I'd sure hate to pop a generator...!

BB. · February 2010

Re: Feeding Outback PS-1 for Aux Charging

You can run the generator and a Iota or equivalent battery charger to directly charge the batteries with your generator (and bybass the inverter's AC input).

It will cost you around $1,000 for a Honda eu2000i from the Internet and $300+shipping or so for an Iota 48 volt 15 amp charger (I can't get to the main Iota page to check specifications--looks like a Honda eu2000i or eu3000i can run this charger--please confirm with somebody who knows more than I).

-Bill

Feeding Outback PS-1 for Aux Charging

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