roof power generators

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Our roof's solar-panel started this year, and it just past its 9 MWh
energy-production milestone.  That's a serious amount of electricity.  We hope
for perhaps 12 MWh this year, about 30% more than we consume.

Hah, we've joined the battle between the sun and the clouds.
https://enlighten.enphaseenergy.com/pv/public_systems/WAJT773668/overview


--  
 Thanks,
    - Win

Re: roof power generators
wrote:

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Nice setup.  Mother nature usually wins the battle.

The problem with the Enphase web site is that their graphs often hide
some interesting things.  This is the output of one of my customers
rooftop solar system which also uses Enphase micro-inverters.
<
http://802.11junk.com/jeffl/solar/380732/total-power-20140613-20160905.jpg

You can easily see the effect of clouds, fog, haze, and trees.  Also
notice the flattened top of the curve in summer, where heating of the
panels causes a reduction in power output.

If you want to grind your own graph, login to your Enphase Enlighten
page:
<https://enlighten.enphaseenergy.com/
and generate a DAILY report starting from the day you started
recording data.  Export as a CSV using the small icon that looks like
an Excel logo at the top right:
<http://www2.enphase.com/enlighten-help/tip/what-reports-are-available/
Use the XLS spreadsheet, or XLT template under:
<http://802.11junk.com/jeffl/solar/380732/
to build the graph.  Just replace the data I left in these and replace
it with your data from the CSV.  You can import everything including
the headers, but then go to the bottom of the data columns and clear
or erase the "total" row or the graph won't work.

If you want to see what's happening on your New England power grid,
see:
<http://www.iso-ne.com
<http://www.iso-ne.com/isoexpress/
Also available on your smartphone:
<http://www.iso-ne.com/about/news-media/iso-to-go
I'm more familiar with west coast data:
<http://www.caiso.com/outlook/outlook.html
--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
We've slightly trimmed the long signature. Click to see the full one.
Re: roof power generators
Jeff Liebermann wrote...
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 Two years of data, that's nice.  We've a ways to go before
 making yearly curves.  We also see a mid-day flattening,
 which I first ascribed to heating, but after more careful
 observation, realized was due to sun-roof geometry.  As  
 the sun squarely lined up with my panels it was too high.

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 Thanks, yes I've done that.  Here's a graph showing
 10 days worth of 5-minute data.
https://www.dropbox.com/s/v1t6tlw2b9cm3so/Solar_2016-April-10-18.pdf?dl=0

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 Fascinating, I didn't know about this.  Thanks!!


--  
 Thanks,
    - Win

Re: roof power generators
Winfield Hill wrote...
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https://www.dropbox.com/s/v1t6tlw2b9cm3so/Solar_2016-April-10-18.pdf?dl=0

 Here's some commentary on the data in the grsph.
https://www.dropbox.com/s/7ypt8c8d05dj3me/Solar_2016-April-10-18.txt?dl=0


--  
 Thanks,
    - Win

Re: roof power generators

how much did the system cost?

what would have been the cost of 9 MWh of electricity?

I'm wondering about the payback time?

m

Re: roof power generators
snipped-for-privacy@yahoo.com wrote...
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 It cost $34k.  The payback time would be 15 years,
 assuming no increase in the cost of electricity.
 Which has definitely NOT been the case lately!!
 The actual payback time will be 5 years, given  
 all the incentives that are passed out.

 Solar production in NE is poorer than say in the
 Southwest, but we have more expensive electricity.
 I had my system installed by a local solar company,  
 but a neighbor did it himself, and paid about half.


--  
 Thanks,
    - Win

Re: roof power generators
wrote:

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$34K?!  That's more like 53 years worth of my electric bill, and I
heat with electricity.  That doesn't include the time-value of money,
either.

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Move.

Re: roof power generators
krw wrote...
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 I've noticed that places with cheap electricity
 seem to also have lots of sun, so the payback
 years are probably about the same.  

 We're happy living in NE, for many reasons.  A
 five-year payback is a no-brainer.  If there
 were no incentives, just a 15-year payback, I'd
 think about it more, but would probably go ahead.

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 Nah.


--  
 Thanks,
    - Win

Re: roof power generators
On Wednesday, September 7, 2016 at 9:11:34 PM UTC-4, krw wrote:
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I agree, Subsidizing solar power in the NE makes no sense to me.  
Electric heat pumps and geothermal is good, subsidize that.
Better windows and insulation, would help in older homes.

Call me stupid, but I pay an extra ~$200 a year to get  
all my electric from the local wind farm*.  
I guess that's my small "feel good" penance.  
(We burn in excess of 1,000 gal. of oil/gas,  
heating the house and driving cars.)    

Win, Someone's paying the $34k, how does that make sense?

George H.  

*(There's no wind farm in my county or I might be
getting a similar size tax break.)
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Re: roof power generators
George Herold wrote...
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 What?  I paid the $34k.  I'm certainly not going to let
 someone else own a piece of my roof!


--  
 Thanks,
    - Win

Re: roof power generators
On Friday, September 9, 2016 at 9:14:38 PM UTC-4, Winfield Hill wrote:
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Oh, I'm sorry I thought you said you had subsidies/ tax breaks  
that cut your cost by 2/3rds.  

George H.  
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Re: roof power generators
George Herold wrote...
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? tax breaks that cut your cost by 2/3rds.  

 Oh, I see your angle.  I wrote a check for $34k, but
 I'll claim $10k from the IRS next year, and the other
 1/3 will dribble in from minting SRECs, one per MWh.
 Eventually taxpayers will pay 30% and other electric-
 rate payers a similar amount.  Electric bill savings
 over a five-year period will pay back the rest.


--  
 Thanks,
    - Win

Re: roof power generators
On 10 Sep 2016 13:36:08 -0700, Winfield Hill

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We don't have SREC's in California, so I don't know much about them.
The scheme seems something that only a commodities speculator could
appreciate or understand.  The state does its best to establish a
speculative market, only to have it set both upper and lower limits on
the price and assess penalties on the utilities if they don't meet
their SREC purchase quotas:
<http://blog.recsolar.com/2013/11/solar-finance-101-whats-an-srec-and-how-much-is-it-worth/
  "The SREC price can range anywhere from $4/SREC to $480/SREC,
  depending on your state, the time the SREC was generated,  
  and SREC market volatility. Like any commodity market, the  
  SREC price is based on supply and demand, so the price  
  can fluctuate."

Looks like the utilities are currently paying $275/SREC in Mass:
<http://www.srectrade.com/srec_markets/massachusetts
That's $0.275/kw-hr, which is much better than the $0.04/kw-hr we get
for net metering in Calif.  If you meet your 12Mw-hr goal this year,
that could mean  
  12 * $275 = $3,300  
back from the utility.  Very nice.

Let's hope that Mass keeps the CRECs in place.  That didn't happen in
California, where the equivalent TREC market effectively died starting
in about 2013:
<http://www.srectrade.com/srec_markets/california

--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
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Re: roof power generators
On 9/7/2016 7:56 AM, Winfield Hill wrote:
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How do you address roof maintenance?  Granted, your asphalt
shingle roof will typically last longer (without significant
maintenance) than any of the roofing technologies, here...

But, eventually, you'll have to put a "second" roof on
(or tear the two that you have off and put on "fresh").

I assume removing the panels and later replacing them
will be a comparable job to a clean installation (?)
as any brackets will have to come up in order to
remove the shingles they've been laid upon.  And,
presumably some care to ensure any holes through the
roof sheathing for the mounts don't become leaks
later...

Likewise, how does it fare wrt trapping snow?  You've got
a respectable pitch but I assume snow will still collect
uphill from the panels (?)  Any worry of ice dams forming and
water backing up under the shingles above?

Lastly, were your incentives conditional on using the grid for
storage?  How would eliding that option affect your ROI?
(would you have scaled back the size of the installation?)

Thx.

Re: roof power generators
Don Y wrote...
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 I'm told the bracket studs stay in place.  But if not,
 that part of the install goes quickly.  With everything
 already cut to size removal and reinstall may not be
 so bad.  But one interesting thing, the panels shield
 the roof from sun and the elements, so that portion
 will last longer.  Also, I imaging someplace around
 the 20-to-25 year point we'll want to upgrade the
 solar equipment.  That may match our tile lifetime.

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 It does fine.  If there's not too much, the snow on
 top slides off fairly quickly, and I didn't observe
 any upside collection.  The 3-4-inch clearance under
 the panels is free from snow.

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 No.  In fact the solar production meter, used for
 SREC calculation, is tied to the panel output; we
 get credit even if we use 100% of the electricity.
 I think 16 states have SREC or TREC programs.  If
 we only had the 30% IRS tax credit, the payback
 time would be about 10 years.  Furthermore, if the
 net metering program were to be changed, and our
 contribution to the grid was priced lower, that'd
 stretch out the payback time.  We could help that
 scene with a Tesla Powerwall, etc., but that'd
 add to the system cost and stretch out payback.
 If this happened after our 5-year breakeven, as
 I fully expect, that'd not be so bad.  Instead of
 free electricity, we'd have to purchase maybe 25%.


--  
 Thanks,
    - Win

Re: roof power generators
On 9/10/2016 6:33 AM, Winfield Hill wrote:
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But, they attach to the roof joists *through* the shingles
(or, you claim to have tile?  I'd have to double-check your
photo...); so, how do you remove and replace the shingles
(tile tends to have a longer life -- though we have many friends
with tile roofs and *buckets* dispersed inside their
"country club" homes to collect the rainwater that comes
*through* the roof!  :< ).

Here, roofs tend to need frequent servicing (I'm due to go
up and brush all the collected pine needles off ours -- lest they
trap moisture and "rot" the roofing material).  And, replacement
every ~10 years (I've babied ours and its now 25+ years old
while most of the neighbors have simply replaced theirs -- once
or *twice* -- in that timeframe).

And, as many roofs are flat (1:12 or even 1:48 pitch), collectors
have to "stand up" off the roof surface -- which makes them
vulnerable to the frequent microbursts coming off the mountains
to the north (of course, the north side of the solar panels is
the elevated end so they act like little wind-sails).

Etc.

As a result, we concluded that the only prudent solar approach would
require first replacing/upgrading the roof to something that wouldn't
need frequent maintenance/servicing.  The costs for that obviously
making the ROI even worse (no tax incentives for those costs)

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Here, the mounts would serve to catch "organic debris" (leaves,
pine needles, palm bark, etc.).  I pull a 35G garbage pail of pine
needles off the roof every month -- and we have NO pine trees
on the property... no deciduous trees, either!

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[Of course, snow isn't a concern, here.  But, it was
a curiosity having lived in NE for many years]

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And, be yet another maintenance issue (wonder what
one of THOSE looks like when it catches fire?  :> )

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Here there has been talk of a *surcharge* on solar customers
"for the privilege" of having the grid as a fallback.
I.e., pay for something you *don't* use!  This is par
for the course -- conserve water and rates go up because
we're not using ENOUGH water (to keep the sewer lines
clear, etc. -- there's ALWAYS some argument to justify
the increases!)

The way around it is, of course, to go TOTALLY off
(electric) grid.  Not something I'm keen on doing at my age.


Re: roof power generators
Don Y wrote...
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 No, shingles.  Ask me in 20 years!

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 We replaced our roof with a 20-25 year version
 just before the solar install.  They recommend
 a new or recent roof.  BTW, this type of issue
 is an example of why I wanted to own the system,
 rather than lease one.

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 The solar panels catching fire?  The install
 includes system shutoff for firefighters, etc.


--  
 Thanks,
    - Win

Re: roof power generators
On 9/10/2016 9:02 AM, Winfield Hill wrote:
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Here, asphalt shingles would be *dust* in 20 years.
The sun just eats things that remain exposed to it.

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Yes, there's a push, here, for you to "lease your roof" to someone
who wants to capture the tax credits, etc.  Silly idea for the
homeowner -- who is then faced with the hassle of trying to
maintain a house *under* all that stuff!

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No.  I was commenting re: your reference to Tesla's "big battery"  :>


Re: roof power generators
On Friday, September 9, 2016 at 11:30:14 PM UTC-4, Don Y wrote:
  
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A neighbor handled that on a recent install by getting a 50-yr
"standing seam" metal roof first.  The panels grip the standing
seams, so the roof is continuous--no perforations.  Looks nice, too.

Cheers,
James Arthur

Re: roof power generators
snipped-for-privacy@yahoo.com wrote...
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 On Friday, September 9, 2016, Don Y wrote:
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 If I lived in a mountainous area, or in the SW, with
 droughts and horrible brush fires, I'd want a metal
 roof anyway.  Some are quite attractive.


--  
 Thanks,
    - Win

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