Xantrex XW contemplated system

pcguy2u · July 2008

Been doing some checking on how best to power my entire house with a pv setup and also need to have my generator (15KW Generac) in the mix.

Kind of ended up with the XW because it has two inputs - grid and generator. And, unlike other mfgs equipment, it is tolerant of the not so great sine waves of a lot of generators. Any other Inverters have two inputs?

Have not commited to this system at the moment, but I have put a huge effort into finding what looks like will work for me. Check out the block diagram below. Sorry that the text is somewhat broken.

Just looking for some constructive comments or concerns. In particular, will I face any unnecessary hurdles with PG&E (utility here in Calif) or with the Calif Incentive program?

Many thanks,
Nick

BB. · July 2008

Re: Xantrex XW contemplated system

California incentive only works with Solar panels in the mix for Grid Tied power... So, I assume you have those too (none in the drawing)?

Also, most net metering type billing (including California's) is based on your solar panels roughly generating as much power as you use--based on Time of Use metering...

In California, TOU metering is mandatory--so if you cannot shift your maximum use of power from the middle of the day nx early evening to nights and weekends, you will be condemned to purchasing the most expensive power--and your solar panel system will have to be somewhat larger to ensure that you zero out your power usage during this time.

If you have unreliable power--the XW a great way to approach the problem.

If, however, your power is reliable and/or you only need a little bit of "UPS" type power--then this is still a pretty expensive way to solve the problem... It would be better to go straight Grid Tied solar and make a small UPS system for the fridge/computer/few lights/radio instead.

Battery maintenance and replacement will be an ongoing labor and expense for the life of the system--and lead acid batteries, so far, are only going up in price.

And, as always, spend your first money on conservation--almost always a better investment than just buying/installing a huge solar array.

Do a few calculations on your cost for your various types of solar power systems (gird tied, hybrid, off-grid, backup UPS) and see what works out best for you.

-Bill

pcguy2u · July 2008

Re: Xantrex XW contemplated system

Hi Bill, for sure PV panels will be there. Here in Bodega Bay (a little out of the way) PG&E has the habit of not placing a high priority on getting power back on after a large strorm or other catastrophe.

They also use this wilderness leg to support creating surplus for the grid at times - not sure how that relates to current intent or intent in general, but it seemed like it happened too frequently. Just last night we were out for 3 hours.

The generator and auto transfer switch are already in place and were there at the time the home was built 3 years ago. The battery backup will be minimal at first and the Generac propane generator will only be used as a last resort.

I will probably upsize the inverter so I can add panels later, if necessary.

Thanks for the fine reply,
Nick

BB. · July 2008

Re: Xantrex XW contemplated system

Nick,

You "pay" for the fine location...

You did not say how much power your home uses... I am not a "green" guy--just conservative and cheap--and I have gotten my power usage down quite a bit... Around 200-250 kWhrs per month.

And because of that, I can backup my house pretty nicely with just a Honda eu2000i (1,600 watt) generator for a family of four (of course, having natural gas is a big help there)...

From what I have seen, the home emergency generators are way to large for me... I can run a fridge+freezer and a few lights for 24 hours straight on 2 gallons of gas or less (if I run the generator 1/2 time--keep the cold stuff cold and a few lights in the evening, should be around 1 gallon of gas per day).

A 12kW backup generator uses around 1-2 gallons of gasoline/propane of fuel per hour, even when lightly loaded.

One thing I have though about, but no tried is using an RV generator--small (better matched to my home's loads), quiet, alternate fuels available, and pretty efficient.

-Bill

pcguy2u · July 2008

Re: Xantrex XW contemplated system

Our power use is about 400KW per month - low by average usage, but not way down there.

There are a couple of other driving forces here though.

As you may know, there is a bill in the Calif Legislature that will cause utilities to pay customers for excess power - I think...........

And who know about a giant earthquake or other over the top catastrophe where the distribution system will be non-existant for some period of time.

I put in a solar water heater and recirc the hot water with DC pumps and in the worst case scenario, a hot shower, cold refer and power to some extent will not be out of the question.

Nick

BB. · July 2008

Re: Xantrex XW contemplated system

Nick,

Sounds like you got the conservation down pretty good...

I too have prep'ed for the "big one"... Mine is the Honda eu2000i and 20 gallons of stabilized fuel. I have looked at solar off-grid too--but so far, the generator is a better deal for me.

But I am in the middle of the SF peninsula--so our power outages are very rare and short (other than the usual car accident and such). So, having fuel and a portable generator for evacuation (if ever needed) plus camping supplies has been my plan.

Never quite sure if solar panels on a 70 year old two story house will survive a major earthquake--should be fine--but who knows.

We have been paying for excess power for years--with E6 TOU, "excess" power is over $0.50 per kWhr now--much cheaper to go with grid tied solar.

I have been watching the "baseline" quantity--which in our area is around 330 kWhrs per month--I have assumed if I stay below that, I should avoid any major "energy surcharges"...

Have fun!
-Bill

pcguy2u · November 2008

Re: Xantrex XW contemplated system

Finally got this system up and working, complete with automatic control of the Xfer switch, or if I prefer, manual control. And I still have the ability to run the house off the generator or to use the generator to feed the inverter and/or to charge the batteries. And when the grid returns to normal, everything else returns to normal.:D

Still need to deal with PG&E and their inspection and so on..........

The good news is that when the grid goes down, the xfer switch transfers and the inverter supplies power to the whole house.

Many thanks for all the input,

Nick

wilsonbh · November 2008

Re: Xantrex XW contemplated system

My planned approach is justified by quality of life issues. I believe that installing the PV array to provide me the major portion of my electric needs by cutting down the expense of my electric requirements will greatly increase my quality of life. I can freely use electricity without that nagging voice in my brain counting down the dollars as the SPA runs or the house heater, etc.

There simply is no way, for me, to otherwise justify the installation of a solar electric system here in Florida. The cost is prohibitive since the state has practically eliminated the rebates. Payback will never be realized in my lifetime, but enhanced quality of life will be almost immediately experienced.

I plan to "piece meal" this system by installing a part at a time, over time. Within a couple of years, I plan to have a 4.1kW system managed by a Xantrex 5.0 grid tie inverter setup on my standing seam metal roof.

Additionally, I currently have installed a whole house generator powered by propane. I have 2 250 gallon tanks that I believe I can stretch into the months of use by powering the house a few hours per day just to keep the refrigerator/freezer working.

I too am not a "green" person but very conservative and thrifty. I'm happy to save a buck where I can and I won't pay out extra dollars just to be "green."

pcguy2u · November 2008

Re: Xantrex XW contemplated system

Hi Wilson, have you incorporated the new tax credits that were approved in October and are effective in 2009 - the Feds eliminated the cap and you now will recieve a 30% discount.

Also though, being frugal is not so different than being green.

In any case, let me tell you about the demand water heater that I added to my solar water heater system - speaking of cost effective. The combination of the two has caused my 500 gallon propane tank to remain at 80% full since I installed the system in early June. I developed a spread sheet to track the effectiveness of the system and it is suggesting the the 80% (400 gallons) is probably going to last beyond 2022.

That is not only cost effective and green, but it will pay for the system within three years........:D

Nick

wilsonbh · December 2008

Re: Xantrex XW contemplated system

pcguy2u wrote: »

Hi Wilson, have you incorporated the new tax credits that were approved in October and are effective in 2009 - the Feds eliminated the cap and you now will recieve a 30% discount.

Also though, being frugal is not so different than being green.

In any case, let me tell you about the demand water heater that I added to my solar water heater system - speaking of cost effective. The combination of the two has caused my 500 gallon propane tank to remain at 80% full since I installed the system in early June. I developed a spread sheet to track the effectiveness of the system and it is suggesting the the 80% (400 gallons) is probably going to last beyond 2022.

That is not only cost effective and green, but it will pay for the system within three years........:D

Nick

I have considered the "on demand" electric hot water system. My hesitation is running a 60 amp circuit to feed it when it operates. I've read that when it cuts on, sometimes it will brown out other systems if you don't have sufficient amperage on your main. I have this but am not convinced it will save any money.

Yes, I am a strong conservative. I absolutely do not support the "green" movement unless it makes economic sense. Much of it does not and I don't trust the market. I suspect much of the so called GREEN stuff one can buy is nothing more than packaging. It's all hype in my view and a fad that will pass in time.

sub3marathonman · December 2008

Re: Xantrex XW contemplated system

I have the Tempra 12 instant hot water setup for just the master bathroom and it works great. I have a regular 200 amp service too and I haven't had any electrical problems, at least in the 7 months I've been using it. Also, I have a TV nearby hooked up to a UPS which would sound an alarm if the voltage dropped.

The only "problem" with the Tempra was I hooked it into the hot water line, because I've got a switch to turn the regular water heater off, and set the Tempra to heat to about 120°. Well, after awhile it stopped working, and now I've found out that if the incoming water is above 107° it won't heat at all, no matter what the setting. But that really isn't any problem at all, it just means I'll leave the water heater off more. :cool:

Xantrex XW contemplated system

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