Any theoretical physicist or astronomers here?

[Texas Contrarian]

Originally Posted by Marcus Aurelius

What is the weak link in converting a home to solar and getting it off the grid.

The cost of batteries is certainly one weak link.

I am looking into the issue now for my place in the Texas hill country. I want to be off the grid, and am finding that the cost of a 100kW bank of of deep-cycle batteries is quite considerable.

Originally Posted by Marcus Aurelius

Solar panels not efficient enough for their cost?

They're getting better all the time, but they're still pretty expensive. I have a small (6 kW) grid-tied panel system on the invisible portion of the roof of my Dallas home. Since I have thick foam walls, geothermal heat pumps, and almost exclusively LED lights, my energy consumption is very low per square foot.

But I'm almost afraid to compute the payback time in years!

[Marcus Aurelius]

They told me 20 years when I asked however they guy then added that the parts don't last that long so you're never free of the system.

[GneissGuy]

Unless you're somewhere that you don't have access to commercial electrical power, solar cells are more expensive than grid power. Some people will point out that you buy the solar cells once and they pay off "forever." The problem is that you could take the money you would use to buy the solar cells, invest it, and pay for your grid power with the investment income for a long time, maybe forever.

Hopefully, solar cell prices will keep coming down.

If you want 24/7 power, you need an an energy storage system. Most of them have high cost vs. payoff problems as well. They also tend to need more ongoing maintenance and replacement costs. People are working to reduce these costs as well.

Another problem is the scale involved. We tend to think of solar power as a few cells on the roof. What if it only works if you cover your entire house and yard with solar cells and chop down all your trees?

Fuel cells sound like a good idea, but right now, they're expensive and tend to not last very long before you have to replace them.

Many of the current systems try to make economic sense based on selling excess energy to the electric company during the day and buying it back at night to get no electric bill overall. This doesn't work if too many people have solar installations and freeload off the utility company for their storage for night and cloudy days.

None of the above means that solar can't work. It helps explain why they haven't replaced the current system yet.

[Marcus Aurelius]

YEP.

[WTF]

Originally Posted by CaptainMidnight

But I'm almost afraid to compute the payback time in years!

LOL.....maybe all you ever going to get out of that investment is inner peace!

[Marcus Aurelius]

Originally Posted by WTF

LOL.....maybe all you ever going to get out of that investment is inner peace!

WTF. The grown ups are talking here. Now go play.

[atlcomedy]

Originally Posted by Marcus Aurelius

We have questions.

I'm not sure what discussion or outcome you were hoping to facilitate with this thread, but I have to say if you are this cryptic in your initial inquiries with the ladies I wouldn't be surprised if you get some unreturned emails/phone calls

[npita]

But I'm almost afraid to compute the payback time in years!

Here are some numbers you can use. (1) If you lived at the equator, under ideal conditions, the sun provides about 1 kW per square meter. An optimistic value for the efficiency of solar panels is about 15%, so here in Texas, you will do worse than 150 Watts per square meter of solar panel and if you assume that you could get 8 hours of sunlight that would give you that much, an overly optimistic number would be 1.2 kW-hours of power in a day from 1 square meter of solar panels. In the Dallas area, you can figure about 13 cents per kW-hour, so the same power you get each day from a 1 square meter solar panel in a day costs $1.04 from the electric company.

[Marcus Aurelius]

Originally Posted by npita

Here are some numbers you can use. (1) If you lived at the equator, under ideal conditions, the sun provides about 1 kW per square meter. An optimistic value for the efficiency of solar panels is about 15%, so here in Texas, you will do worse than 150 Watts per square meter of solar panel and if you assume that you could get 8 hours of sunlight that would give you that much, an overly optimistic number would be 1.2 kW-hours of power in a day from 1 square meter of solar panels. In the Dallas area, you can figure about 13 cents per kW-hour, so the same power you get each day from a 1 square meter solar panel in a day costs $1.04 from the electric company.

I'm in the worst scenario.
Atlcomedy, it hasn't happened yet but it may.

[Texas Contrarian]

npita, thanks for that analysis. Very interesting.

The numbers look pretty consistent with my experience so far. Although it's obvious that such a system looks like a very unwise choice, the generous rebate from Oncor helps. I got a check back for about $20K.

I'm looking into an off-the-grid system for my hill country place west of Austin, primarily because I plan to build a house on top of a steep hill far from power lines. It would be nice to have reliable power as well as avoid all those ugly poles running through my property.

I'm looking into a deep-cycle battery and inverter system and finding that batteries are very expensive indeed. M.A., is this the sort of setup you're considering, or are you looking for something else?

Any way you slice it, producing power this way looks very expensive -- perhaps several times more so than simply connecting to the grid. But sometimes that's just not a good (or even possible) choice.

This is a forum largely dedicated to discussions of the HDH experience, as well as other issues of interest to "Diamonds and Tuxedos." Perhaps this could serve as the official HDKWH thread!

[Sydneyb]

Originally Posted by atlcomedy

I'm not sure what discussion or outcome you were hoping to facilitate with this thread...

I'm confused. I thought that theoretical physics was about the math that develops the theory of the our existence? I admit, I googled the phrase because I was thinking Brian Greene (swoon ) or Einstein and got completely lost in Solar power; which seems to be based on straight ROI analysis and not theory. Is a discussion on solar power the direction you were looking for on this thread?

[Guest083011]

There was an interesting piece on "60 Minutes" a few weeks ago, that looks like it could get you and many others off the grid:
http://www.cbsnews.com/video/watch/?id=6228923n

[GneissGuy]

Originally Posted by SR Only

There was an interesting piece on "60 Minutes" a few weeks ago, that looks like it could get you and many others off the grid:
http://www.cbsnews.com/video/watch/?id=6228923n

The Bloom box looks really interesting. There's no science fiction involved, either. However, it does use natural gas and produces CO2. The big questions for the Bloom box are initial cost, reliability, lifetime, efficiency, and long term economics.

[Marcus Aurelius]

Well WR104 is pointed right at us. It's 8,000 light years away and is at the end of it's life cycle. I was wondering if that is a great enough distance for us to be safe. It did some digging myself and found out that it is indeed close enough to fry us. Say if it collapsed and shot out a gamma ray burst 7,999 years ago or so we'd find out after it's too late of course.

[georgeofjungle]

The weak link is getting off the grid. Going solar and staying on the gird eliminates the need for storage of surplus electricity (you sell it to the gird), plus you have a built-in backup system. If you want to leave the grid for philosophical reasons, I'd recommend doing it gradually. Start with a solar water heater - most bang for the buck, especially if most of your hot water usage is in the evening. If you want to leave the grid for geographical reasons, save-up a lot of money first.