Grid-tied solar

MossRoad · Feb 24, 2015

Loren49 said:
http://rredc.nrel.gov/solar/old_data/nsrdb/1961-1990/redbook/atlas/serve.cgi

It looks like we're both in the poorest solar areas in the US. Locally there are a good number of small to medium sized solar installations. My point is that even with the available construction subsidies, the only way that a profit will happen is if an adequate amount of electricity is produced. The proposed project will still require a sizable investment and its hard to believe that these investors did not require good information that it will be profitable. Also note that during the time period (October to March) of greatest cloud cover the area has it shortest daylight and the electrical demands are lower. Over the rest of the year there are the greater hours of sunshine and the higher electrical demand. In my area many installations are on roofs and are covered with snow part of the winter but over the long summer days and with a relatively flat orientation the yearly output is enough.

Loren

Link doesn't work. What was it to?

MossRoad · Feb 24, 2015

aczlan said:
I was talking to a town councilman (an engineer) recently about the installation at the town buildings (not far from Lake Ontario) and he said that even on 10-15 degree overcast days, if there is a little bit of the panel peeking out from under the snow, it will clear the whole panel off.

Aaron Z

Loren49 said:
In my experience they do clear in moderate temperatures but when its -20 F its plenty slow. Many will be blown clear with a good breeze if it is was very cold when it snowed. I've had fixed mounted panels for 25+ years but adjusted them to vertical over the coldest months...very little ice or snow problem. They are fixed east/west but were hinged so I could adjust angle to sun. My current setup is fixed at an angle so I do have a bit more snow issue. I now clear them when needed with a roof scraper (not sure the right name) Actually I have gone south for 2 months the past 2 years so my good son does it!

Loren

Loren

I just pulled a foot of snow off of my roof that was taking days to melt and making icicles (its called a roof rake

). I know that our driveway is black asphalt. And if I plow it early enough on a sunny day, by days end, its melted and dry, but only of its above 15-20 degrees. Anything colder and it doesn't matter. Of course, our driveway isn't angled towards the sun, so that would help a bit, too.

I just don't see the energy savings payback at my location for solar as being acceptable VS investing in the stock market. I mean really, our electric averages about $100-120 per month for the year. So let's say $1500 for the year. How much would a solar installation that could power my home with lights, fans, and appliances in winter, pool, air conditioning, lights, and appliances in summer cost? Estimates at over $20K from people in my area. It would take 15 years just to break even. Take a $20k chunk and stuff it in the stock market and I get $40k in 7 years and $80K by year 15. I'd have only saved $22,500 in electric bills (discounting any maintenance/repairs on the system), and the system would be 5 years from end of life (based on 20 year life span). I'd be out over $57K.

MossRoad · Feb 24, 2015

dave1949 said:
I ran pvwatts with the same parameters as above (except I added 3 degrees of tilt) for Portland, ME. The result is 1,397.1 mwh per year compared to 1,248.8 mwh per year for South Bend, IN. That is 11.9% less in South Bend than Portland.

Portland models 10.3% higher than Waterville, ME, the location I use for my system. Modeling my system based on Waterville predicts 4.828 mwh/year which comes pretty close to my actual output of 4.984 mwh/year. The 156 kwh difference between the prediction and my actual output amounts to 7 reasonably sunny days per year. The older version of pvwatts that was used to size my system modeled at 4.447 mwh/year. The new version is more accurate but still conservative.

Running pvwatts for South Bend using my system size (4.32 dc kilowatts), standard 15% efficiency panels, 40 degree fixed-angle, roof-mounted, facing due south, the prediction is 5.326 mwh/year compared to my actual output here of 4.984 mwh/year. Using my actual 70 degree mounting angle in South Bend, the prediction is 4.542 mwh/year. Changing my system from 70 to an optimal 45 degree angle predicts 5.264 mwh/year--slightly less than if my system were in South Bend all other things being equal.

Micro-climates and perceptions aside, the numbers say South Bend (probably at the airport) is not appreciably different than my home. pvwatts is thought to be a reasonably accurate tool for solar system sizing. Unless there is something known to be wrong with the weather data or model for South Bend, or you can identify a small micro-climate effect specific to a given site, I think I would trust it.

A pv solar system functions as a very expensive insolation meter in addition to generating power. Remember there are almost infinite graduations between dark and full sun. Not all cloudy or clear days are created equal.

Thanks for running those numbers. I appreciate it and will look deeper. :thumbsup:

dave1949 · Feb 24, 2015

MossRoad said:
I just don't see the energy savings payback at my location for solar as being acceptable VS investing in the stock market. I mean really, our electric averages about $100-120 per month for the year. So let's say $1500 for the year. How much would a solar installation that could power my home with lights, fans, and appliances in winter, pool, air conditioning, lights, and appliances in summer cost? Estimates at over $20K from people in my area. It would take 15 years just to break even. Take a $20k chunk and stuff it in the stock market and I get $40k in 7 years and $80K by year 15. I'd have only saved $22,500 in electric bills (discounting any maintenance/repairs on the system), and the system would be 5 years from end of life (based on 20 year life span). I'd be out over $57K.

I'm not trying to talk you into a solar system, but there are few issues you didn't include in the comparison.

1) The sun is more reliable than the stock market and the timing of its performance is very predictable.

It shines through bull and bear markets, recessions and depressions. No one can abscond with the sunshine. It is immune to speculators and human error. Supply and demand of sunshine are immaterial.

2) You may double your money consistently for 15 years, or you may not. If you do and want the funds it going to cost you 15% in capital gains on any sale price above your basis. Plus you will likely generate taxable dividend and interest income every year. The value of the output of a solar system is not taxed but beware the possibility of personal or real property taxes levied on a residential solar system.

3) The price of electricity, especially in Indiana which is currently very reliant on coal, is likely to increase over the next 20 years. At annual inflation and price increases of 1.5% for 20 years, $1320 ($110/month) today will become $1778. 2.5% price increase plus inflation would become $2163. Unless your home becomes a lot more efficient or your demand declines, either of those two numbers is more probable than a flat $1320 for 20 years.

4) Your scenario is based on being able to pay your electric bill and invest in the stock market. I'm sure you can but that is not an apples to apples comparison to what happens to the $20,000 in an either/or choice because you have removed the burden of paying for the electricity from the invested funds. You could evaluate investing in any home energy-related project and reach the same conclusion as you did for solar pv when it's not a true either/or choice--you are choosing both of two possibilities simultaneously for the same set of funds.

MossRoad · Feb 25, 2015

Good points. However, in the next 10-20 years cloud cover is expected to increase in this area, as is precipitation. I believe its supposed to do that for most of northern U.S. and Canada. There are too many unpredictable events to rely on solar in this area. We are also in tornado alley. Have any studies been done on how solar panels hold up to high winds, flying debris and large hail? And energy companies are pushing to lessen and even eliminate the programs where they will buy any of your unused power because it puts undue burden on customers that don't have solar installations. How much does maintenance on the solar equipment, batteries, etc... cost? I have zero maintenance on my current electrical system. I just don't see the energy savings payback on the investment being worth it in this location.

There is a huge solar installation at the Indy airport. That is being touted as quite successful... until you pull the government and utility subsidization from the equation. The Indianapolis Light and Power Company buys the solar electricity for 3-4 times MORE than they can sell it. They compensate by raising the rates to their customers. Financially, it doesn't make logical sense. Its tree hugger voodoo economics (and I'm a tree hugger). :confused2:

Loren49 · Feb 25, 2015

MossRoad said:
Link doesn't work. What was it to?

Not sure why it didn't work. It was a national map showing amount of solar efficiency (not correct term). I believe it showed 5 different levels and we were in the 4th. Seattle area and Alaska were in the 5th.

Loren

Loren49 · Feb 25, 2015

MossRoad said:
Good points. However, in the next 10-20 years cloud cover is expected to increase in this area, as is precipitation. I believe its supposed to do that for most of northern U.S. and Canada. There are too many unpredictable events to rely on solar in this area. We are also in tornado alley. Have any studies been done on how solar panels hold up to high winds, flying debris and large hail? And energy companies are pushing to lessen and even eliminate the programs where they will buy any of your unused power because it puts undue burden on customers that don't have solar installations. How much does maintenance on the solar equipment, batteries, etc... cost? I have zero maintenance on my current electrical system. I just don't see the energy savings payback on the investment being worth it in this location.

There is a huge solar installation at the Indy airport. That is being touted as quite successful... until you pull the government and utility subsidization from the equation. The Indianapolis Light and Power Company buys the solar electricity for 3-4 times MORE than they can sell it. They compensate by raising the rates to their customers. Financially, it doesn't make logical sense. Its tree hugger voodoo economics (and I'm a tree hugger). :confused2:

Remember also that the viability of coal and other fossil fuel generating economics will likely change over the next 10 to 20 years. Also the hidden costs of pollution and mining may cover some of the premium now given as an incentive to renewables. I don't thing its as black and white as you conclude. Many things have been subsidized as a way of kick starting their use but that's a discussion for another place. (many existing established things are still subsidized and many hidden costs are passed on to tax payers)

All of my solar and associated material (batteries, inverters, regulators) have been purchased with no subsidies or incentives. I think you would find that many small stand alone systems were purchased in the same way. Its work quite well and I've enjoyed the independence.

Loren

dave1949 · Feb 25, 2015

MossRoad said:
Good points. However, in the next 10-20 years cloud cover is expected to increase in this area, as is precipitation. I believe its supposed to do that for most of northern U.S. and Canada. There are too many unpredictable events to rely on solar in this area. We are also in tornado alley. Have any studies been done on how solar panels hold up to high winds, flying debris and large hail? And energy companies are pushing to lessen and even eliminate the programs where they will buy any of your unused power because it puts undue burden on customers that don't have solar installations. How much does maintenance on the solar equipment, batteries, etc... cost? I have zero maintenance on my current electrical system. I just don't see the energy savings payback on the investment being worth it in this location.

There is a huge solar installation at the Indy airport. That is being touted as quite successful... until you pull the government and utility subsidization from the equation. The Indianapolis Light and Power Company buys the solar electricity for 3-4 times MORE than they can sell it. They compensate by raising the rates to their customers. Financially, it doesn't make logical sense. Its tree hugger voodoo economics (and I'm a tree hugger). :confused2:

A solar system would be covered for those Act of God perils under a typical homeowner's insurance policy. Stock market investments are not insured or insurable. The value (principle) of an investment is exposed to much higher risk in the stock market.

Yes, utility revenue streams are beginning to be and will continue to be upset by local generation. Their operating income plan is not designed to accommodate that. Who knows how that will play out over time? For certain, the utilities' backs are against the wall a bit on the issue. The more local generation eats into their revenue, the more they need to raise their rates or move to peak usage billing--which encourages more local generation.

To me the important financial question is how can carbon-related emissions be reduced without putting us in the poor house? I see carbon footprint reduction as an over-arching imperative that we aren't going to avoid. As I showed in my post #752 about my personal returns on solar pv, I can achieve that at no cost; actually I can earn a little while achieving that goal without being subsidized. That is a reasonable outcome; I'm not making a pile of money but it's not costing me anything to reach a goal either. I see this as a "pay me now or pay me later" scenario when "later" is going to be more expensive.

fordmantpw · Feb 25, 2015

MossRoad said:
Have any studies been done on how solar panels hold up to high winds, flying debris and large hail?

From the testing reports I have seen, they stand up better than the shingles on the roof.

In reality, what does it matter? If you have significant storms, it will be a claim on your homeowner's insurance, and the solar panels will be repaired/replaced as necessary based on the policy. I've checked with my agent and there is not additional fee, solar panels are included as if they were part of the house.