Sustainable Energy without the Hot Air- Great Read

[FUEGO]

Yep, I just got a kill a watt too. $20 from amazon. Not sure if this will allow me to save $20 in electricity though, since most things that use 1-4 watts when plugged in but off are going to remain plugged in year round to avoid the hassle factor.

Ultimately, I know our heating/cooling is roughly 2/3 of our energy costs, so all the worry about unplugging things that consume 1 watt does very little to reduce our overall energy consumption. Changing the thermostat by 1 degree for a month during the peak heating/cooling season would roughly equal a dozen of these 1 watt devices plugged up year round.

Everyone doing a little bit only helps a little bit.

On a different note, we only spend around $1200 a year on heating/cooling, so a lot of the items we could do to increase our heating/cooling efficiency may have long payback periods (assuming we keep living here forever) even with the federal and power company credits/rebates. Not sure what would have the shortest payback period. New doors or weatherizing existing ones? New windows? Reflective barrier in attic? Solar attic fans in the eaves? High SEER a/c system? Only paying $1200 a year makes it too easy to "do nothing". Gotta love cheap energy!


The one thing that may have a good payback locally is solar or wind generation. 30% federal credit plus 35% state credit (up to $10,000). Plus I think I can sell my power to some green power initiative for around $0.20 per kWh as long as I don't net meter. I'm sure I have done the math wrong, but the payback period is only 6-7 years from a quick and dirty back of envelope amateur estimation. Plus I could make money sooner if I sell the equipment for a decent salvage value in 5 years after the recapture provisions do not apply and then buy a new system (assuming credits are in place) and do the whole thing over again. Gotta love perverse incentives that entice one to act economically inefficient.

 

[Zathras]

Solar PV is GENERALLY the last thing you want to do from a financial standpoint.
Insulation is one of the quickest paybacks. I have seen some people with poorly insulated houses (in climates that need the insulation) have a payback period under one year.
Conservation should also come before solar as it costs you nothing (as you say though, you have to find the things that will actually add up).
I haven't heard of anyone selling power from a home PV or Wind power generator to anyone but the local utility. However, if it works out that way in your area and they will give you 20cents/kWh, more power to you

 

[FUEGO]

I haven't heard of anyone selling power from a home PV or Wind power generator to anyone but the local utility. However, if it works out that way in your area and they will give you 20cents/kWh, more power to you

I need to do some more research obviously because it seems too good to be true. But I think solar PV (or any solar for that matter) might actually have a short payback just because I would only be paying 1/3 the cost and getting over 2x market rates for produced power. Whether the hassle of maintaining my own utility system is worth possibly a couple thousand bucks a year max is another issue... And I would be stuck relying on the continued subsidized purchases of electricity by the green energy initiative.

 

[Zathras]

I would be very interested in hearing what you find out.
With a payback rate of double the use rate and if there are better rebates in your state I could see a much shorter payback period.
Last year we were actually getting paid one-tenth of a penny more for surplus energy than we are paying for electricity They changed the rates though and they are no just a tenth of a penny less for surplus energy
Overall though, on an anual basis we still use more than we produce, so it doesn't make that much of a difference.

 

[FUEGO]

I would be very interested in hearing what you find out.
With a payback rate of double the use rate and if there are better rebates in your state I could see a much shorter payback period.
Last year we were actually getting paid one-tenth of a penny more for surplus energy than we are paying for electricity They changed the rates though and they are no just a tenth of a penny less for surplus energy
Overall though, on an anual basis we still use more than we produce, so it doesn't make that much of a difference.

Per my understanding of the local plan, it actually pays more to NOT net meter, because you get paid around double if you don't net meter. If you do net meter, every kWh you produce offsets the standard kWh charge (8-9 cents), and I guess they pay you either the 8-9 cents if you produce more than consume, or some reduced wholesale generation rate. It seems perverse, but that wouldn't be the first time something government subsidy related ended up producing perverse results.

 

[Nords]

Yep, I just got a kill a watt too. $20 from amazon. Not sure if this will allow me to save $20 in electricity though, since most things that use 1-4 watts when plugged in but off are going to remain plugged in year round to avoid the hassle factor.

Considering what you do with spreadsheets for "green fun", I'd just write off the Kill-A-Watt against your entertainment budget...

When I look over my spreadsheet, I see that some of our phantom loads are surprisingly robust. 30 watts for a powerstrip supporting a TV and a couple of VCRs. 15 watts for a powerstrip supporting a desktop computer and all its accessories.

One way to knock down the hassle factor is to plug the phantom loads into the receptacle controlled by a light switch. We conveniently have one behind our audio/video stack that gets switched off when the TV watching is done. The only thing that stays powered up is the TiVo.

To go to extremes, Ed Begley had his house wired with a kill switch. When he goes out he flips one switch by the door that has the same effect as popping the house's electrical supply breaker. Of course he must not mind the blinking LED clocks or having to reprogram VCRs. And that sort of wiring is difficult to retrofit.

On a different note, we only spend around $1200 a year on heating/cooling, so a lot of the items we could do to increase our heating/cooling efficiency may have long payback periods (assuming we keep living here forever) even with the federal and power company credits/rebates. Not sure what would have the shortest payback period. New doors or weatherizing existing ones? New windows? Reflective barrier in attic? Solar attic fans in the eaves? High SEER a/c system? Only paying $1200 a year makes it too easy to "do nothing". Gotta love cheap energy!
The one thing that may have a good payback locally is solar or wind generation. 30% federal credit plus 35% state credit (up to $10,000). Plus I think I can sell my power to some green power initiative for around $0.20 per kWh as long as I don't net meter. I'm sure I have done the math wrong, but the payback period is only 6-7 years from a quick and dirty back of envelope amateur estimation. Plus I could make money sooner if I sell the equipment for a decent salvage value in 5 years after the recapture provisions do not apply and then buy a new system (assuming credits are in place) and do the whole thing over again. Gotta love perverse incentives that entice one to act economically inefficient.

Like saving for ER, it's always easier to reduce your consumption than to raise your production.

Here's the out-of-the-box questions to ask yourself:
- Could you do without A/C by passively cooling the house? Insulated walls, shaded roof, awning-style windows allowing whole-house airflow? There's a narrow band of latitudes and microclimates where this works.
- Can you do the work? Attic reflective foil is very cheap but installation is a cast-iron bitch (even worse when it's hot). Solar exhaust fans and ridge vents (either one, not both) require slicing into your roof, not for the novice handyman.
- Can you seal off most of the house in winter and only heat one or two rooms? Agreed that for $1200/year you'd be crossing the line from frugality into deprivation pretty quickly.
- Would you be able to save money with a tankless water heater?
- Does your utility offer time-of-day use and load-shedding credits?
- If your fridge is over five years old or over 20 cu ft then you may be able to go for a 19 cu ft EnergyStar model with a payback of less than five years. But that depends on several other lifestyle factors. The best deals are the Craigslist sellers who are getting rid of last year's EnergyStar models because the color doesn't match this year's remodel.

Depending on your winter weather, solar water may have the quickest payback. If it freezes then you'd have two heat-transfer loops (one using antifreeze). If it doesn't freeze then you could do your own work for about $1000-$2000 in parts (before the tax credits) and it would only use energy when it was hot. The water heater would still have an electrical heating element for days when the sun's just not keeping up.

If you go the photovoltaic depreciation option, let me know when you're ready to get rid of your used panels!

I need to do some more research obviously because it seems too good to be true. But I think solar PV (or any solar for that matter) might actually have a short payback just because I would only be paying 1/3 the cost and getting over 2x market rates for produced power. Whether the hassle of maintaining my own utility system is worth possibly a couple thousand bucks a year max is another issue... And I would be stuck relying on the continued subsidized purchases of electricity by the green energy initiative.

Per my understanding of the local plan, it actually pays more to NOT net meter, because you get paid around double if you don't net meter. If you do net meter, every kWh you produce offsets the standard kWh charge (8-9 cents), and I guess they pay you either the 8-9 cents if you produce more than consume, or some reduced wholesale generation rate. It seems perverse, but that wouldn't be the first time something government subsidy related ended up producing perverse results.

Some smart PUC is going to get wind of that good deal and kill it. Our local HECO rate is about 18-22 cents/KWHr (so far this year, 4.7% increase on the way) but our HPOWER trash-burning plant only gets about 5-10 cents/KWHr as a wholesale producer. So net metering pays off for us.

I'm not sure what utility maintenance hassle you're referring to. I don't even have to clean our PV panels.

If you search Craigslist daily (and set up an eBay search) you'll quickly find PV panels at discounts of over 50%. I've been paying no more than $4/watt including shipping. Again this is a job for an experienced handyman, but none of it is particularly complex. The best situation is where you hire an electrician to wire in the first few hundred watts and then you expand the system on your own. That's how you pay only $15K for a $35K retail system.

We bought in Oct 2004, started up our system in Feb 05, and finished expanding it by Nov 07. After the tax credits we've been hitting a dividend rate of 7-10%/year, better than anything in our equity portfolio. We'll break even on our initial investment in the next 8-10 months, weather permitting, and the compounded returns will pull ahead in 10 years after that.

Since the tax credits are still in effect, I'm almost hoping that the hurricane will rip it all off the roof so that I can start over with what I've learned...

 

[FUEGO]

Considering what you do with spreadsheets for "green fun", I'd just write off the Kill-A-Watt against your entertainment budget...

That's what I told the DW!

When I look over my spreadsheet, I see that some of our phantom loads are surprisingly robust. 30 watts for a powerstrip supporting a TV and a couple of VCRs. 15 watts for a powerstrip supporting a desktop computer and all its accessories.

One way to knock down the hassle factor is to plug the phantom loads into the receptacle controlled by a light switch. We conveniently have one behind our audio/video stack that gets switched off when the TV watching is done. The only thing that stays powered up is the TiVo.

30 watts for tv/vcr? Wow! I'd definitely switch off to save that. Our tv+computer is 4 watts combined (off), so I don't feel bad about that being passively consumed all the time.

The main rat's nest of equipment in the computer room stays plugged in 24/7 so we can have sleep resume on the PC's, cable modem/router/wifi/vonage. I haven't tested the loads of much of that, but we like the wifi in and around the house and the phone on 24/7

Here's the out-of-the-box questions to ask yourself:
- Could you do without A/C by passively cooling the house? Insulated walls, shaded roof, awning-style windows allowing whole-house airflow? There's a narrow band of latitudes and microclimates where this works.
- Can you do the work? Attic reflective foil is very cheap but installation is a cast-iron bitch (even worse when it's hot). Solar exhaust fans and ridge vents (either one, not both) require slicing into your roof, not for the novice handyman.
- Can you seal off most of the house in winter and only heat one or two rooms? Agreed that for $1200/year you'd be crossing the line from frugality into deprivation pretty quickly.
- Would you be able to save money with a tankless water heater?
- Does your utility offer time-of-day use and load-shedding credits?
- If your fridge is over five years old or over 20 cu ft then you may be able to go for a 19 cu ft EnergyStar model with a payback of less than five years. But that depends on several other lifestyle factors. The best deals are the Craigslist sellers who are getting rid of last year's EnergyStar models because the color doesn't match this year's remodel.

Get rid of a/c? Impossible. 95 degrees and 95% humidity for half the summer here. The dr's bills from heat stroke would offset any energy savings. And there would be the divorce attorney's fees too.

Depending on your winter weather, solar water may have the quickest payback. If it freezes then you'd have two heat-transfer loops (one using antifreeze). If it doesn't freeze then you could do your own work for about $1000-$2000 in parts (before the tax credits) and it would only use energy when it was hot. The water heater would still have an electrical heating element for days when the sun's just not keeping up.

Solar water heating and time of day usage plus load shedding may be options. Although we only use approx $150 a year on water heating with nat gas. However the tax credits and rebates make solar WH affordable. We do get frequent (sometimes constant) freezing weather during the winter months, so I'm not sure how much the net savings would be if resistive electrical heat is the backup water heating source.

If you go the photovoltaic depreciation option, let me know when you're ready to get rid of your used panels!

I'm not sure what utility maintenance hassle you're referring to. I don't even have to clean our PV panels.

If you search Craigslist daily (and set up an eBay search) you'll quickly find PV panels at discounts of over 50%. I've been paying no more than $4/watt including shipping. Again this is a job for an experienced handyman, but none of it is particularly complex. The best situation is where you hire an electrician to wire in the first few hundred watts and then you expand the system on your own. That's how you pay only $15K for a $35K retail system.

We bought in Oct 2004, started up our system in Feb 05, and finished expanding it by Nov 07. After the tax credits we've been hitting a dividend rate of 7-10%/year, better than anything in our equity portfolio. We'll break even on our initial investment in the next 8-10 months, weather permitting, and the compounded returns will pull ahead in 10 years after that.

Since the tax credits are still in effect, I'm almost hoping that the hurricane will rip it all off the roof so that I can start over with what I've learned...

Maybe you could sell your current PV panels as they age beyond 5 years and buy new ones to take advantage of more credits?

I wasn't sure about maintenance. I'm a newb, but I thought they had to be cleaned occasionally? And I assume there may be corrosion or wear/tear and weathering on connections? Hail or flying debris could crack a panel? Further research is required as I figured it wouldn't be easy to just set and forget for years without the occasional troubleshooting.

 

[FUEGO]

One thing I will be doing is paying a little more attention to power consumption when buying new appliances and electronics if the data is available. Take, for example, a TV that uses 140 watts when on vs. 80 watts when on. If used 6 hrs a day, that 140 watt tv costs $15 extra a year. So maybe $75 over the useful life of a tv. I might have to take my Kill A Watt with me next time I go to walmart or bestbuy.

 

[Zathras]

I wasn't sure about maintenance. I'm a newb, but I thought they had to be cleaned occasionally? And I assume there may be corrosion or wear/tear and weathering on connections? Hail or flying debris could crack a panel? Further research is required as I figured it wouldn't be easy to just set and forget for years without the occasional troubleshooting.

More research sounds like it is in order.
Our panels are warrenteed up to 2 inch hail.
Cleaning? Mine have been up almost 2 1/2 years with no need for cleaning. Your results may vary depending upon your location and local weather. We have lots of freeze/thaw cycles, snow and they have been hit with hail (3/4 inch at most). No issues with any of the above.
For example, if you are in an area with a high likelyhood of hurricanes, I would definately check with the installer about that.

 

[FUEGO]

More research sounds like it is in order.
Our panels are warrenteed up to 2 inch hail.
Cleaning? Mine have been up almost 2 1/2 years with no need for cleaning. Your results may vary depending upon your location and local weather. We have lots of freeze/thaw cycles, snow and they have been hit with hail (3/4 inch at most). No issues with any of the above.
For example, if you are in an area with a high likelyhood of hurricanes, I would definately check with the installer about that.

We usually don't get more than 3/4 inch hail and that is only a couple times a year. We are in the approach/take off path for many geese, and goose feces would be all over these panels by the end of summer. Sometimes they land on the roof and poop on it too. re Hurricanes - we get tropical storms or remnants every few years it seems and strong hurricanes hit us or nearby areas every decade. Plus we get high winds a lot during regular storms since we have no tree cover and live at the end of a canyon basically (the lake basin). I'd definitely have to engineer the attachment to the roof to withstand some serious wind. May be more important to call the insurance company to see if they have a "solar panel" rider to their policy.

 

[Sam]

Weaknesses of Kill a watt

I like the product a lot, but wish it could be improved to support:

Current higher than 15 amp.
230Volt.

Sam

 

[FUEGO]

I like the product a lot, but wish it could be improved to support:

Current higher than 15 amp.
230Volt.

Sam

I think I saw some much more expensive power management/power monitoring devices that had more features and could do 240v and higher current. But they were also over $100 IIRC and the Kill a watt I got was $20.

 

[Zathras]

Fuego, with the considerations of the weather in your area, I would definately get good detailed information about the installer's and manufacturer's warentee and gaurentees.
We live near some water and have a number of ducks and geese (although it sounds like not nearly as many as you). Normal rain has taken care of any dirt/debri on the panels.
Ask for references from any installers. Then you can get the experiences of other solar panel owners in your area.

 

[ERD50]

I like the product a lot, but wish it could be improved to support:

Current higher than 15 amp.
230Volt.

Sam

I'd like to have something like this:

Google PowerMeter

The details are sketchy or buried, but somewhere I saw that it gives power usage for each circuit, and graphs the history for you as you specify, and you can compare time frames, etc. I would like that, especially if [-]there were government subsidies [/-] I could count on everybody else paying for something I would use.

The testimonials of the trial users are underwhelming. As seems typical, they suddenly "discover" that it helps to do things they should have been doing all along... "I cleaned my refrigerator coils for the first time in 15 years"... " Wow, my space heater uses a lot of power, I guess I should turn it off when I'm not home"...." Hey, I can save energy by doing a full load of dishes or clothes".....

But I would probably learn something. I wish I had one for my well pump, I had a leak that went undetected until it got bad enough to start seeing dips in pressure.

I'm thinking of wiring a little circuit up - use a high resistance value divider to tap off a few volts from the 220 supply to the pump, rectify it and hook it up to a cheap analog clock with the power in place of the battery. I could monitor how many hours the pump runs with that.

-ERD50

 

[samclem]

I could monitor how many hours the pump runs with that.

-ERD50

Hours? Hopefully it's not running that much. Most folks doing rough estimates of water use figure 60 gallons/day per person for drinking, hygiene, toilet flushing, washing clothes and dishes, etc. This usually comes pretty close to the mark (though the presence of teenage girls typically requires a bump-up). The major additions to this would be for any livestock or plant/garden/lawn watering.

If your pump is moving 5 gal/min (per your note below, which sounds a bit slow to me for a 1/3hp pump--maybe you've got a very deep well?), then all the domestic water typically used by one person in a day would take just 12 minutes of pump time. Even with a few folks at home and a generous sprinkler system, I wouldn't guess the well pump would be operating much past an hour.

 

[ERD50]

Hours? Hopefully it's not running that much.

Ahh, sorry for the confusion, I see I did not give the denominator. It *will* run for *hours*, but it might take a few days I was just thinking "hours" because it is a clock. More generically, I could say I want to monitor the average duty cycle over a measured time frame.

Timing and gallons per cycle are very rough numbers, but it is a 190' deep well. I roughly estimated about an hour a day and with 4 in the house that would be lose to the numbers you have. But when I had the leak, I'm pretty sure it was running for hours a day before I noticed it.

-ERD50

 

[samclem]

Ahh, sorry for the confusion, I see I did not give the denominator.

Gotcha. I made a poor assumption.

Let's see: Such a pump probably draws approx 4 amps at 230V= approx 1kw. At the average US electrical rate it costs about ten cents to pump all the water your family needs for an entire day (almost 2500 lbs of water) up from a location over 100 feet below the ground. It always amazes me what a tremendous bargain electricity is. We may whine and complain about the size of our electric bills, but it's probably among the best values in my monthly budget.

When we moved into our house I briefly considered hooking up to the nearby city water. I'm so glad I didn't. Though I had to invest a lot in my water treatment system, I saved the $4000 hookup costs, $25 per month in water bills, and I have better tasting water than I would have had if I'd gone with the municipal water.

 

[ERD50]

It always amazes me what a tremendous bargain electricity is.

Yes. Back in post 100, I mentioned I was surprised that my porch lights might be costing me $16/month. Well the surprise was warranted - that was 16KWHrs, not dollars. I forgot to multiply by $0.1 per KWHr, so one dollar and 62 cents per month. The motivation to unscrew a couple of the bulbs dropped to zero.

So now I have very roughly accounted for ~ 1/2 my base electrical usage during the non-heating/cooling season - time to start adding up computers, tvs and lighting, and see if I have any large phantom loads. The phantoms I've checked so far are not even worth buying a power strip for.

-ERD50

 

[HFWR]

But this brings us back to 115,000,000 households, times 16KWh...

A KWh here, a KWh there, and pretty soon we're talking about real money.

Apologies to Sen. Dirksen aside, I'm sure that many of us [-]cheap bastards[/-] frugal types have already found the low-hanging fruit. Many haven't...

 

[ERD50]

But this brings us back to 115,000,000 households, times 16KWh...

A KWh here, a KWh there, and pretty soon we're talking about real money.

Apologies to Sen. Dirksen aside, I'm sure that many of us [-]cheap bastards[/-] frugal types have already found the low-hanging fruit. Many haven't...

Yes, but if someone else has not picked the low hanging fruit already, why should my tax dollars go towards paying for a fancy "smart meter" when 90% of that could be done with no expenditure at all, just some simple education and a little effort on their part? I suspect that 90% of the people who haven't figured this stuff out, won't figure it out after being given a smart meter either.

Here's an (awful) idea - just like a drivers license, we should require an "energy consumer's license". You want to buy electricity from the utility company, you have to pass a test to show that you know how to use it properly.

I think it would be simpler and more effective to just tax the stuff. When gas was $4, people found all sorts of ways to conserve. That's not theoretical, it is a fact, consumption went down. We know it works, it happened w/o any stupid "cash for clunkers" bill, or any CAFE standard changes... but no one wants to go there.

-ERD50

 

[FUEGO]

I think it would be simpler and more effective to just tax the stuff. When gas was $4, people found all sorts of ways to conserve. That's not theoretical, it is a fact, consumption went down. We know it works, it happened w/o any stupid "cash for clunkers" bill, or any CAFE standard changes... but no one wants to go there.

You have my vote. Now if you can just convince the other 49.99999999% of the electorate. Hey, what are you doing in 2012? Looking for a running mate? I hear Palin might not be up for it, so if not, give me a PM.

I think if everyone's utilities rates doubled, there would be a lot more conservation going on in the most efficient manners possible, and we could even waste the tax revenues on stuff like paying down the national debt, funding the next stimulus bill, or heck, even shaving off a fraction of a percent from everyone's tax rates!

 

[FUEGO]

I did a little more research on the organization that buys PV solar power at $0.19 per kWh. They are a non-profit that seems to be loosely funded and affiliated with the state government, and they are housed at the local state U. They sign agreements with small producers of 10 kW systems or less. The rate used to be $0.22 until last year, then they lowered it due to "reduced cost of PV generation". However everyone receiving the old rate is grandfathered in. I need to call them and see how many years the "agreements" last and also determine the solvency of this agency and just how government backed (if any) they are. They have a long list of over 200 PV generators in the state (mostly residential), and at least a handful are in my city, so I'm sure I can talk to experienced residential generators. The $0.19 per kWh is based on $0.15 premium from the green power organization and the approx $0.04 that the power company pays for wholesale power. The green power org charges green minded bozos $0.04 per kWh extra to buy green energy (like offsets I guess), but somehow they will pay me $0.15. Something smells a little fishy in terms of sustainability, to borrow a word from the green movement.

Their PVWATTS program tells me a 3 kW DC system will generate around 3900 kWh annually using the assumptions they have for my city and the monthly sun strengths. I think these assumptions allow for a 23% inefficiency between the theoretical raw solar DC wattage and the AC wattage at the meter due to, among other things, a 5% reduction for dusty/dirty PV cells.

Quick back of envelope calcs say if I can get panels installed at a total cost of $4.5/watt, I will get a 16% payback each year, plus a 50% salvage value in year 6. A realistic installed cost is probably closer to $9 per watt based on the online calcs they had at the sites I visited. Which reduces the yield of this to the point where it probably isn't worth the hassle.

Or in dollar terms, if I put $30,000 into a 6.67 kWh system, it would cost me $10,500 after state and fed credits and produce 8749 kWh or $1,662 a year. Then in year six I could scrap the whole thing and if I could clear $2.25 per watt, make another $15,000. Making this little venture nicely profitable.

I am constrained a little on roof real estate, with only ~1200 sf, and 300 of that slopes downwards towards the north, so not sure how useable that is. Any idea is 900 sf of roof space could accomodate 3 kW or 6 kW? I also have around 8000 sf in the fenced back yard on ground level that could theoretically be used.

I definitely need to dig into this a little more. Partly because playing with stuff like this is fun, and partly because I like making money if it isn't too much work. And as an engineer, all my coworkers will be jealous of my technical prowess at building a powerplant at my house.

 

[samclem]

And as an engineer, all my coworkers will be jealous of my technical prowess at building a powerplant at my house.

But will PV provide the technical challenge you desire? I saw a very cool web page/document several years ago (can't find it now) that described a way to make cheap pseudo-parabolic trough mirrors by putting a slight bend in mirror-coated regular plate glass. Maybe put about ten of these 4'x6' mirrors in your back yard. Design some solar tracking devices linked to servos and a "power tower" with a stirling cycle engine or a small steam turbine (a fun project in itself) and you'd be off to the races. This would give you WAY more bragging rights than a few solar panels on the roof.

 

[FUEGO]

But will PV provide the technical challenge you desire? I saw a very cool web page/document several years ago (can't find it now) that described a way to make cheap pseudo-parabolic trough mirrors by putting a slight bend in mirror-coated regular plate glass. Maybe put about ten of these 4'x6' mirrors in your back yard. Design some solar tracking devices linked to servos and a "power tower" with a stirling cycle engine or a small steam turbine (a fun project in itself) and you'd be off to the races. This would give you WAY more bragging rights than a few solar panels on the roof.

That was part of my thinking as well. I was already thinking about the comparative advantage of some sort of non-PV solar powered micro power plant.

I was wondering if microturbines were out there on the market today. I'm just thinking that the neighbors might tar and feather me if the tracking somehow screwed up and I burnt down their houses with a targeted solar beam. Or the whole neighborhood. The townhouses across the street went up in a massive conflagration a couple years ago with some high winds and dry conditions, destroying 37 units I think. There's frugral (PV) and cheap (getting tarred and feathered).

 

[Nords]

I wasn't sure about maintenance. I'm a newb, but I thought they had to be cleaned occasionally? And I assume there may be corrosion or wear/tear and weathering on connections? Hail or flying debris could crack a panel? Further research is required as I figured it wouldn't be easy to just set and forget for years without the occasional troubleshooting.

We usually don't get more than 3/4 inch hail and that is only a couple times a year. We are in the approach/take off path for many geese, and goose feces would be all over these panels by the end of summer. Sometimes they land on the roof and poop on it too. re Hurricanes - we get tropical storms or remnants every few years it seems and strong hurricanes hit us or nearby areas every decade. Plus we get high winds a lot during regular storms since we have no tree cover and live at the end of a canyon basically (the lake basin). I'd definitely have to engineer the attachment to the roof to withstand some serious wind. May be more important to call the insurance company to see if they have a "solar panel" rider to their policy.

Every time I'm on the roof I check the panels, and there's never anything to clean. I don't know if occasional rain or dew takes care of everything or there's just not enough air pollution to deposit any dust.

Retail panel racks are usually warranteed at 100 MPH and some commercial racks are rated up to 150 MPH, although I doubt that a residence roof is rated to survive that.

The trick is not to build a monolithic array of airtight [-]lifting surfaces[/-] panels but rather to allow an inch or two between the panels to let the breezes blow. Our racks are screwed into the beams of our cathedral ceiling with 1.5" bolts (plus silicon caulk) so I sure hope that holds.

I know that commercial installations are insured, but the cost of a homeowner's PV policy may greatly prolong the payback. We have a huge hurricane deduction so I haven't bothered to check. But then we don't have hail at our altitude and I keep the area clear of hurricane missile hazards.

I did a little more research on the organization that buys PV solar power at $0.19 per kWh. They are a non-profit that seems to be loosely funded and affiliated with the state government, and they are housed at the local state U. They sign agreements with small producers of 10 kW systems or less. The rate used to be $0.22 until last year, then they lowered it due to "reduced cost of PV generation". However everyone receiving the old rate is grandfathered in. I need to call them and see how many years the "agreements" last and also determine the solvency of this agency and just how government backed (if any) they are. They have a long list of over 200 PV generators in the state (mostly residential), and at least a handful are in my city, so I'm sure I can talk to experienced residential generators. The $0.19 per kWh is based on $0.15 premium from the green power organization and the approx $0.04 that the power company pays for wholesale power. The green power org charges green minded bozos $0.04 per kWh extra to buy green energy (like offsets I guess), but somehow they will pay me $0.15. Something smells a little fishy in terms of sustainability, to borrow a word from the green movement.

So they're going broke slowly, which eventually would leave you scrambling for a net-metering agreement. But in the meantime you'd still be making most of your own power and I doubt the utility would make you unplug from the grid.

Their PVWATTS program tells me a 3 kW DC system will generate around 3900 kWh annually using the assumptions they have for my city and the monthly sun strengths. I think these assumptions allow for a 23% inefficiency between the theoretical raw solar DC wattage and the AC wattage at the meter due to, among other things, a 5% reduction for dusty/dirty PV cells.

It's probably accurate to within 25%. I know that most inverters are at least 95% efficient and most panels are around 12-14% efficient, although later models are pushing 18-20%.

The problem is local conditions. None of the website calculators handle vog, but it nailed us 10% last year. Most of the website calculators don't handle seasonal variations, and even at 23 degrees latitude we have a swing of 25% from winter to summer. If you're in a microclimate that's always cloudy or rainy then PV is just not worth the effort.

Quick back of envelope calcs say if I can get panels installed at a total cost of $4.5/watt, I will get a 16% payback each year, plus a 50% salvage value in year 6. A realistic installed cost is probably closer to $9 per watt based on the online calcs they had at the sites I visited. Which reduces the yield of this to the point where it probably isn't worth the hassle.

Those are good numbers. The issue is how long you'll be living in the house to enjoy the payback, and whether the payback calculators factor in a 5% inflation rate in utility costs-- or whatever your local utility has been able to get away with.

A local company has put nearly a megawatt of panels on top of the state's airport buildings, selling the power to the state at 32 cents/KWHr fixed for 20 years. This made lots of sense last year when electricity rates were 29 cents/KWHr and gas was $4/gallon, but not so much this year when fuel costs have plummeted and electric rates have dropped to 18 cents/KWHr. The state has been taking a lot of heat from the media, but in five years they'll no doubt be back up in the 32 cents/KWHr range.

Or in dollar terms, if I put $30,000 into a 6.67 kWh system, it would cost me $10,500 after state and fed credits and produce 8749 kWh or $1,662 a year. Then in year six I could scrap the whole thing and if I could clear $2.25 per watt, make another $15,000. Making this little venture nicely profitable.

Yup. Assuming you use all those credits within the first couple years, although they carry forward for a long time.

I am constrained a little on roof real estate, with only ~1200 sf, and 300 of that slopes downwards towards the north, so not sure how useable that is. Any idea is 900 sf of roof space could accomodate 3 kW or 6 kW? I also have around 8000 sf in the fenced back yard on ground level that could theoretically be used.

You're going to have to do the math on the panel dimensions, and unfortunately the high-power-density panels are pretty pricey. I wouldn't try to use anything facing north unless you could find an angled rack to elevate the panels south.

I definitely need to dig into this a little more. Partly because playing with stuff like this is fun, and partly because I like making money if it isn't too much work. And as an engineer, all my coworkers will be jealous of my technical prowess at building a powerplant at my house.

It's all worth it just to watch an analog meter spin "backwards"...