Article 690 question

[tallgirl]

I thought I'd give my local solar power contractor (Texas Solar Power Company) a call and see if it would be cheaper to put in some sort of standby system before I ran off and had a Generac installed in May. It would seem that with tax rebates and whatnot that a PV battery backed system might well be competitive.

They want to run the wires from the array to the charge controller under the eaves in EMT. I'd prefer they were buried in RNC for a variety of reasons. He didn't know if that could be done, and the only thing article 690 mentions about wiring methods is that any DC wiring inside a house must be enclosed in a metal raceway.

(And I am going to suggest they join the forum whenever we get a chance to meet face-to-face.)

 

[LawnGuyLandSparky]

Are power outages that frequent? Last incident we had here was the Northeast grid failure, and I rather enjoyed it. First time in a long time I saw stars in the sky at night!

 

[iwire]

Julie, I seriously considered adding some solar to my home to help reduce my costs. Once I did some research it became clear that the best way to save money on my electric bill was to use less power.

Now you seem to have a different plan in mind but I think the same problem comes up.

Battery maintenance / replacements.

Obviously you can make it work and it would be cool but I think it will be less 'green friendly' than the fossil fuel generator.

 

[acrwc10]

I can't see any reason not to. I would make sure they ground the system framing and supports. I worked on a job recently and every time I touched the metal supports I would get a static shock. Ouch. Once I touched a grounded emt to it it stopped happening. I didn't think the "pay back" on the units after tax rebates was that great. Something like 8 to 12 years. What kind of numbers are you hearing?

 

[tallgirl]

Julie, I seriously considered adding some solar to my home to help reduce my costs. Once I did some research it became clear that the best way to save money on my electric bill was to use less power.

I don't think solar, without massive rebates, can help with costs at this time, for the reasons you mentioned below.

Last night I was at a friend's house for dinner and mentioned that I'd contacted TSPCO and the first question out of the husband's mouth was "how long until it pays for itself?" My answer was "Never". I think it will generate about $0.70 per day. Not exactly a way to pay off that sort of investment. Oh, and my POCO, TXU Electric, doesn't do rebates ...

Now you seem to have a different plan in mind but I think the same problem comes up.

Battery maintenance / replacements.

Perhaps if some of y'all have maintenance experience with Generac generators that would be helpful in making a decision.

Obviously you can make it work and it would be cool but I think it will be less 'green friendly' than the fossil fuel generator.

Well ... I dunno. I know there is some controversy over the amount of energy it takes to produce PV systems in the first place.

 

[tallgirl]

Are power outages that frequent? Last incident we had here was the Northeast grid failure, and I rather enjoyed it. First time in a long time I saw stars in the sky at night!

I don't know why we have lousy power in the neighborhood where I live, but I average more than 4 hours per year without electricity, and much of that is for more than 5 minutes. The important things in the house -- computers and network gear -- will run for about 15 or 20 minutes without electricity, but that doesn't help the other important things, like the fridge.

As for the stars -- I was in Folsum, LA, about 50 miles north of New Orleans, the Friday after Katrina. Other than when I've camped, that was the first time in decades I'd seen so many stars, and the first time in a very long time that I'd seen the Milky Way.

 

[George Stolz]

If emergency backup is the big thing, then perhaps skipping the panels and just installing a battery bank and a charger would be cheaper along that route. For all but four hours of the year, you're connected to a power source. There's no reason to install another power generating system if during that period you'll be running off the batteries anyway.

I'd go for a natural gas/propane generator and TS myself.

 

[LawnGuyLandSparky]

If emergency backup is the big thing, then perhaps skipping the panels and just installing a battery bank and a charger would be cheaper along that route. For all but four hours of the year, you're connected to a power source. There's no reason to install another power generating system if during that period you'll be running off the batteries anyway.

I'd go for a natural gas/propane generator and TS myself.

And here I'm thinking, because most people heat with it anyway, a diesel generator around 9.5 Kw is enough to carry just about any home comfortably through a 2-day outage.

They really ought to make a reasonably priced, 4 x 20a circuit automatic transfer switch.

 

[acrwc10]

generators all the way.

generators all the way.

I would skip the solar with batterys, The systems I have been seeing pay back at a better rate them $0.70 a day. but they are feeding back onto the power grid ussing an inverter and two way meter. No batterys. The last one I saw was $ 50 k with a $20 k rebate from the poco. It was putting out 5000 watts on a clear day.
As far as gensets go http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200306416_200306416
This is a very reliable unit and comes with an ATS prewired.

 

[Bea]

They want to run the wires from the array to the charge controller under the eaves in EMT. I'd prefer they were buried in RNC for a variety of reasons. He didn't know if that could be done, and the only thing article 690 mentions about wiring methods is that any DC wiring inside a house must be enclosed in a metal raceway.

I agree as long as the RNC does not run through the interior of house to get to the inverter

 

[tallgirl]

I agree as long as the RNC does not run through the interior of house to get to the inverter

It wouldn't -- it would run a rather tortuous path through the backyard to where all the hardware would be on the side of the house.

-----

Some background for those of y'all who've suggested either generators or ditching the solar panels and just charging batteries, the system I told them I wanted designed and quoted should provide similar functionality to a standby diesel or natural gas generator, while being eligible for some amount of the current federal tax credit.

Another requirement I laid on TSPCO is that the system be designed in a way that should either TXU Electric or the State of Texas begin providing rebates, it could be readily expanded to take advantage of those rebates. That's part of the motivation for wanting to use RNC -- if I later expand things with the rebate money and put an array down my back fence line, the DC cables from that array would be too large to fit in a reasonable sized piece of EMT tucked up under the eaves.

Functionally, it's like an immediate standby natural gas generator, capable of delivering a peak of more than 5kW with an average runtime in excess of the longest outage I've ever had (8 hours * 800w average = 6.4kWh. That 800w is excluding heat and A/C, which I could live without for a typical 4 hour outage). Financially, it's like a natural gas generator (high cost, no payback except convenience) with a small rebate that can be "upgraded" to a grid-tied PV system as soon as someone else is willing to pay the bill for more panels. Additionally, it should "generate" (because I specified they use a grid-tied inverter) between $250 and $300 per year in electricity, which should significantly offset battery replacement costs.

 

[solarerika]

According to 2005 NEC, unfortunately the solar input is supposed to be in metal conduit from when it enters the building to the point of the first disconnect. Why the "need" for metal disappears after that, I have no idea. It is a half-baked item in my opinion.
Comparing a solar powered backup solution to a fossil-fuel generator is like comparing apples and oranges. Generators sit there waiting to be used. The solar (if grid-interactive) can be working for you even when the grid is up.

 

[PV System]

There's no reason to not bury DC wiring in RNC. I do it all the time. But it has to be in EMT once you penetrate any structure up to the first disconnect.

I'd recommend getting a system that has grid-tied and battery backup capabilities. (Beacon inverter is one we use a lot). If you only have a charge controller, you'll be wasting a lot of energy.