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Old 04-17-2013, 10:43 AM
 
89 posts, read 117,611 times
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Quote:
Originally Posted by Mack Knife View Post
Did you factor in the installed cost of the generator, the maintenance for that system? You use the installed costs of solar but seem to use only the fuel costs for the coal fired generator system. The generator and it's related systems and maintenance are free? Not buying that. I'm not saying that those costs would make solar less expensive but if you compare one installed cost to only the fuel cost of another, your comparison isn't valid.

Will your generator last 15 years without a major overhaul or replacement? Doubtful. It will require significant maintenance over that period of time. Oil changes, filter changes, fuel system maintenance and so on. Is there a license required for the generator? In many locations a special license is required to use a coal or fossil fuel fired generator for residential use.

If you can run your generator for a total cost of $360 per year, I can sell those systems all day and eliminate any energy shortages in this country practically overnight. I don't believe it.

That generator probably cost much more than 10k to which is added the costs of installation, system design, configuration and so on. Since you applied those same costs to the solar power system you must also apply them to your comparison.

Still, it would be interesting to see the actual costs of procurement, installation, maintenance for your system in total and then run that against a solar power system at a reasonable installed cost (which is not $5/watt BTW).

Also, did you factor the 30% tax credit (cash in your pocket) for solar? I doubt you got that much, if any for installing that coal fired system.
You obviously sell these systems.
Good for you and i hope you remain prosperous.

I agree with alot of what you are saying. My point is that solar power in not the panacea that people make it out to be. The equipment also does not last long. Like I said 15 years. People always say."but the company warrenties it for so and so years" Most the companies havent lasted that long.

The 30% tax credit is not money in your pocket. It is like borrowing $30 and having to pay back $100.
Looks good today but not so good tomorrow. That money has to come from somewhere. Eventually your pocket and at triple the cost.

The gassifier and generator is cheap. Probably much less than 10k. To be honest, id love to sell them. But EPA says no. Besides, coal is not so easy for most people to get and probably even illegal in green states. It is also physically dirty. I am working on a wood pellet version thou.
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Old 04-17-2013, 12:12 PM
 
7,281 posts, read 8,829,402 times
Reputation: 11419
Quote:
Originally Posted by Jedcolton View Post
You obviously sell these systems.
Good for you and i hope you remain prosperous.

I agree with alot of what you are saying. My point is that solar power in not the panacea that people make it out to be. The equipment also does not last long. Like I said 15 years. People always say."but the company warrenties it for so and so years" Most the companies havent lasted that long.

The 30% tax credit is not money in your pocket. It is like borrowing $30 and having to pay back $100.
Looks good today but not so good tomorrow. That money has to come from somewhere. Eventually your pocket and at triple the cost.

The gassifier and generator is cheap. Probably much less than 10k. To be honest, id love to sell them. But EPA says no. Besides, coal is not so easy for most people to get and probably even illegal in green states. It is also physically dirty. I am working on a wood pellet version thou.
I don't sell anything related to solar power and never will. I just spent some time learning about the stuff instead of repeating things I don't know for myself. I use solar and know that you can pay a lot of money for very little benefit or do it right, spend a lot less and get a lot more.

Of course solar power isn't a panacea, it is just one solution that can be part of a total system to provide energy. It all comes down to needs and then planning with knowledge and experience.

BTW, a tax credit is money in your pocket. A tax credit is a refund of sorts. Sure the money has to come from somewhere, it all does. That doesn't detract from the reality though, it is cash, not a deduction. On a system costing $20,000 you get a check for $6,000. While there are concerns about where a tax credit comes from, one can take advantage of it or let someone else take it. One thing is certain, someone will.

There are tradeoffs with any system. Fossil fuels are dirty and someone ends up paying for that too, in health issues or regulations and taxes imposed to manage air quality. It is one big circle, nothing is free.

The bottom line is you use what works for you and try to manage the costs as much as practical. Seems you have a system that provides you with all the power you need. Lots of people never get close to that, they just pay a utility company. So hats off to you, you've accomplished more than many dream of.
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Old 04-17-2013, 03:58 PM
 
1,278 posts, read 1,057,774 times
Reputation: 836
Quote:
Originally Posted by Jedcolton View Post
What are you. Somew kid at school with a calculator.
Try getting some real experience.

I have a big roof.
What people dont ever seem to concider is that the sun only shines 8-12 hours per day. That is if the clouds dont obstruct it or dirt dosent get all over them. They also only reach maximim output when the sun is perpendicular to the panel. If you dont have trackers you will collect much less power.
I averaged about 4kwh per hour and 30kwh per day form the 20kw.
If you feed that into a battery you lose around 20% then
lose it on the way back out thru the inverter and losses in the wiring. I got about 20kwh per day of useful power. Like I said. Barely heated the water.
Cant use solar water collectors where I live. Too cold.
I tried heatpipes but they have the same problem with tracking and snow dosent melt off of them.
Real world experience huh?

I get 30 kwh from 5 kw in March, avg.
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Old 04-17-2013, 04:26 PM
 
1,278 posts, read 1,057,774 times
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Quote:
Originally Posted by Jedcolton View Post
There is summer. But not so much. But there is a lot of sunshine.

It takes about 8kw to heat a 50 gallon water heater from around 70F. Water here even in the summer is 50f or less so it takes more. if you have a fammily you will need to heat that tank at least 3 times perhaps m more.

Charging a battery is not free. Even the better battery chargers/charge controllers are less than 90% efficient. You always have eddy current and hysteresis losses in the transformers not to mention resistance losses in diodes and wiring. There is a reason those diodes and transistors are attached to huge heat sinks.

Batteries themselves also have specific charge/discharge efficiencies with lots of varriables. This efficiency can be between 50 and 90% More than likely near 75%
8 kw is power. I can give you 8 kW with one lead acid battery (SLI) . What you need is Energy. The water needs to be heated to a delta of 70 degrees from 50 so that it is at 120.

Lets see 1 btu is needed to raise 1 pound of water by 1 degrees and there is .8.34 pounds of water per gallon.

50 gallons x 8.34 pounds / gallon x 1 btu / pound = 417 btu x 70 = 29,190 btu of energy

29,190 btu = 8.5 kwh at an efficiency of like 15% and you would need like 10 panels easy. 17 sq ft / panel

Solar water heaters are 80% efficient. The average winter insolation in continental american northern climates is at least 4 hrs of 1000 w/m2 of sunshine.

On a typical winter day, two 30 sq. ft collectors are about 5.5 meter sq. can give you

5.5 meter squared x 1000 w/m2 x 4 hrs = 22 kwh x 70 % = 15.4 kwh (reduced efficiency to ensure expectations will be met.)

There you go. Tell me where you live and ill have someone give you a quote so you don't bad mouth the industry by doing it yourself.
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Old 04-17-2013, 05:30 PM
 
Location: DC
6,504 posts, read 6,423,574 times
Reputation: 3102
Someone has been exposed.
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Old 04-17-2013, 07:35 PM
 
89 posts, read 117,611 times
Reputation: 91
Quote:
Originally Posted by Werone View Post
8 kw is power. I can give you 8 kW with one lead acid battery (SLI) . What you need is Energy. The water needs to be heated to a delta of 70 degrees from 50 so that it is at 120.

Lets see 1 btu is needed to raise 1 pound of water by 1 degrees and there is .8.34 pounds of water per gallon.

50 gallons x 8.34 pounds / gallon x 1 btu / pound = 417 btu x 70 = 29,190 btu of energy

29,190 btu = 8.5 kwh at an efficiency of like 15% and you would need like 10 panels easy. 17 sq ft / panel

Solar water heaters are 80% efficient. The average winter insolation in continental american northern climates is at least 4 hrs of 1000 w/m2 of sunshine.

On a typical winter day, two 30 sq. ft collectors are about 5.5 meter sq. can give you

5.5 meter squared x 1000 w/m2 x 4 hrs = 22 kwh x 70 % = 15.4 kwh (reduced efficiency to ensure expectations will be met.)

There you go. Tell me where you live and ill have someone give you a quote so you don't bad mouth the industry by doing it yourself.


Well, I supose you are thinking about evacuated tube collectors. Plate collectors have the same problems. There are many problems with these.
1st. To keep the fluid from freezing, you must use glycol. But when you use glycol you need to be very careful with high temps. Very easy to obtain in evacuated tube systems. If the glycol gets warmer than 250F it turns into acid and is no longer antifreeze so your pipes rupture. Depending on your fittings, they will disolve too.
2. The snow and ice does not melt off the collectors. Then they dont work. Usually for the rest of the winter because no one in their right mind will climb up on the ice covered roof.
3. If you use a pump and circulate the glycol. You lose as much heat as you gained during the day time.
4. Drainback does not work with evacuated tube collectors. If for what ever reason the pump does not come on, the tubes will melt. Or if it comes on late and the tubes are hot, you risk steam explosion or again glycol degradation.
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Old 04-17-2013, 09:20 PM
 
1,278 posts, read 1,057,774 times
Reputation: 836
Quote:
Originally Posted by Jedcolton View Post
Well, I supose you are thinking about evacuated tube collectors. Plate collectors have the same problems. There are many problems with these.
1st. To keep the fluid from freezing, you must use glycol. But when you use glycol you need to be very careful with high temps. Very easy to obtain in evacuated tube systems. If the glycol gets warmer than 250F it turns into acid and is no longer antifreeze so your pipes rupture. Depending on your fittings, they will disolve too.
2. The snow and ice does not melt off the collectors. Then they dont work. Usually for the rest of the winter because no one in their right mind will climb up on the ice covered roof.
3. If you use a pump and circulate the glycol. You lose as much heat as you gained during the day time.
4. Drainback does not work with evacuated tube collectors. If for what ever reason the pump does not come on, the tubes will melt. Or if it comes on late and the tubes are hot, you risk steam explosion or again glycol degradation.
Propylene glycol comes either inhibited or nonihibited, if you choose the inhibited glycol, something like tyfocor brand, the the working temperature is well above 212 F. What happens then is that most manufacturers of solar thermal equipment ensure the collectors can stagnate, (under no load) for a long period of time. Stagnation temperatures can reach over 400 F in hot weather.

Solar thermal manufacturers know the displacement, or amount of fluid that needs to exit the collectors under a no load condition, and allow the collectors to stagnate. What this does is steam the water in the water/glycol mixture, causing the glycol to exit the collectors and take up volume in an expansion tank therefore protecting the glycol. This feature is known as steamback.

The evacuated tubes nowadays can withstand long periods of stagnation. This is because of a redesign. Older tubes had a heat transfer fluid that could degrade if the collector was allowed to stagnate, something like the old Viessmann tubes. This was also engineered to be installed with a heat dump to protect the glycol and tubes from degrading but the system was subject to bad controllers and of course bad installations.

Done right, solar thermal systems are very effective. Oh and you must always use a pump in these indirect closed loop systems, but the efficiency is very high and the robustness is incredible.

Solar thermal systems need the glycol changed every like 15 years but system life is 30+, solar electrical, a 40 year lifespan.
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Old 04-17-2013, 10:40 PM
 
89 posts, read 117,611 times
Reputation: 91
Quote:
Originally Posted by Werone View Post
Propylene glycol comes either inhibited or nonihibited, if you choose the inhibited glycol, something like tyfocor brand, the the working temperature is well above 212 F. What happens then is that most manufacturers of solar thermal equipment ensure the collectors can stagnate, (under no load) for a long period of time. Stagnation temperatures can reach over 400 F in hot weather.

Solar thermal manufacturers know the displacement, or amount of fluid that needs to exit the collectors under a no load condition, and allow the collectors to stagnate. What this does is steam the water in the water/glycol mixture, causing the glycol to exit the collectors and take up volume in an expansion tank therefore protecting the glycol. This feature is known as steamback.

The evacuated tubes nowadays can withstand long periods of stagnation. This is because of a redesign. Older tubes had a heat transfer fluid that could degrade if the collector was allowed to stagnate, something like the old Viessmann tubes. This was also engineered to be installed with a heat dump to protect the glycol and tubes from degrading but the system was subject to bad controllers and of course bad installations.

Done right, solar thermal systems are very effective. Oh and you must always use a pump in these indirect closed loop systems, but the efficiency is very high and the robustness is incredible.

Solar thermal systems need the glycol changed every like 15 years but system life is 30+, solar electrical, a 40 year lifespan.


Yes, but like I said, when the collector stagnates, the propolyne glycol degrades. Nothing you can do about it. It degrades at 212 but is very quick at 250 and copper in contact with the solution increases the rate of decay conciderably. Copper is almost mandatory at higher temperatures. Nothing you can do about it.

I found this out the hard way after a large investment in collectors that I thought would last me many years. But on the third winter they froze and burst due to the degrading propolyne glycol.

How do you get past the snow and ice problem?
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