Author Topic: Going Solar  (Read 7746 times)

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Offline daniel1948

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Re: Going Solar
« Reply #90 on: April 02, 2019, 09:44:58 AM »
Speaking of Maui's dependence on oil generated electricity, I read this item today about recent approvals for grid scale solar PV and storage projects in Hawaii, including on Maui:
https://www.hawaiianelectric.com/six-low-priced-solar-plus-storage-projects-approved-for-oahu-maui-and-hawaii-islands

On Maui a 60MW solar PV farm + 240MWh of storage, with an energy cost of 8c/kWh.

So like so many places now, the costs of the technology has fallen so much that a rapid transition to renewables is increasingly feasible, and becoming a no-brainer in locations with an expensive dependence on fossil fuel generation.

And abundant sunlight.

This is great news. Hawaii is a progressive place. What I wonder is how the above compares to the total energy generation there, and how much it will lower overall electricity cost. If this is 10% of the island's power use it won't have a big effect on a homeowner's electric bill. If it's 90% it will make rooftop solar too expensive to bother with. But I expect to use a lot of electricity when summer hits in full force, so I'll enjoy my solar and I won't feel bad about the expense until grid power drops to 12¢/kWh or so.

The fact that they say they'll pass on the actual cost to the consumer without markup makes me think it will be a small part of the overall power generation and grid power will remain highly dependent on oil, and expensive. But it's a great start.
Daniel
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Offline Alex Simmons

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Re: Going Solar
« Reply #91 on: October 16, 2019, 11:49:24 PM »
Thought I'd revisit with an update. I recently paid my quarterly electricity bill, which makes a full year of bills to compare with the previous two years without solar PV system:

Quarterly Bill Comparison Before and After Solar PV

Quarter      Before*    After^  Difference
Jan – Apr    $1,561      $587        -$974
Apr – Jul      $886      $379        -$507
Jul – Oct    $1,001       $82        -$919
Oct – Jan    $1,297      $566        -$731
------------------------------------------         
TOTAL        $4,745    $1,614      -$3,131
 
 * Average of the quarterly bills for the
   two years prior to installation of solar
   PV system
 
 ^ 11kW PV, 10kW inverter, Rural Mid-North NSW


I won't have the same opportunity for like with like comparison moving forward, as from early in the new year an extra building on my property will be occupied adding to the overall consumption.

A $3.1k reduction in total bills per year means a tick over 4 year payback period.

Offline daniel1948

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Re: Going Solar
« Reply #92 on: October 17, 2019, 11:41:00 AM »
I'll add my own update:

To summarize: 32 panels and 2 Powerwalls for the main house, 16 panels and 1 Powerwall for the cottage, occupied by a renter.

Update:

Both the house and the cottage have more than enough panels. Typically the Powerwalls are full by noon for the cottage and by early afternoon for the house. My electric usage (main house) is almost all during the day. A/C is unneeded after I go to bed, typically around 7:00 to 8:00 p.m. One time I drove to Lahaina and back, returning in the early afternoon, and since the car is still charging on 120 v. (still waiting for the electrician to install a 240 v. outlet) it charges very slowly. I forgot to stop the car charging before I went to bed and in the morning the Powerwalls for the main house were down to 40%. That's the lowest they've gone. More often they're between 50% and 60% in the morning.

The cottage is another matter. The renter works. So except for daytime A/C to keep her dog comfortable, which comes directly from the panels, all her electric use comes from the Powerwall, which holds 13 kWh. The result is that often by morning the one PW for the cottage is at zero in the morning and the cottage has been drawing 45 to 64 kWh per month from the grid. I do not get net metering. The utility won't even take my excess solar for free. I can feed back a very small amount for load balancing. There is a $25 minimum charge, plus a $1.17 fee, and that gets me about 42 kWh per month. Over that I pay about an additional 30¢ to 32¢ per kWh. Under that I pay the minimum fee. These numbers are approximate because the fee structure is too complicated for me to figure exactly. There's a flat customer fee of $11.50, plus a whole long list of types of per-kWh charges that all get added up, plus $1.17 at the end.

Anyway, the point is that the bill for the cottage ends up being $5 to $10 over the minimum. Installing another Powerwall would eliminate that, but it's hardly worth $7,000 to save $5 to $10 per month. I could probably eliminate the entire cottage bill by combining the house and cottage onto one account. There would be only one minimum payment instead of two, and the three Powerwalls combined would probably be enough for the house and cottage together. But I'd have no way to prevent a renter from going way overboard on electricity. And the renter will be leaving soon (her company is moving her to another island to start a new project) so the lease I inherited will terminate and I can make the next renter pay their own electric bill.

Through the hottest months of summer, for the main house I never paid more than the minimum. The house has consistently used around 25 kWh per month from the grid, which is for load balancing and A/C-compressor start-up, since I still have a fast-start compressor.
Daniel
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"Anyone who has ever looked into the glazed eyes of a soldier dying on the battlefield will think long and hard before starting a war."
-- Otto von Bismarck

Offline Alex Simmons

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Re: Going Solar
« Reply #93 on: October 18, 2019, 03:32:07 PM »
I should add:

Since it was installed (about a week or so short of a year), my solar PV system has
  • Generated 13.76MWh of electrical energy
  • Reduced CO₂ emissions by 11.14 tonnes*
and of that we have:
  • Self consumed 6.51MWh (47.3%)
  • Exported to grid 7.25MWh (52.7%)

Our total consumption has been 13.05MWh, so our solar PV has offset 105% of our consumption.

*  based on the average emissions of our grid's power generation, which are fairly high, > 0.8t CO₂ / MWh due to coal being the dominant energy source. It is dropping slowly (0.85 last year to 0.81 this year) as renewables increase their proportion of total energy supply.

Offline Alex Simmons

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Re: Going Solar
« Reply #94 on: October 18, 2019, 03:42:36 PM »
Anyway, the point is that the bill for the cottage

We are currently building a "granny flat", so our overall consumption will go up once that's occupied by my elderly mum. It won't be separately metered/billed by energy company. I'll install our own meter so we can have the data on the energy consumption of the extra dwelling.

It might be after we complete some renovations over the next year that we add some solar PV capacity.

when I say "granny flat" I mean a small home. Expansive views though:

« Last Edit: October 18, 2019, 03:50:28 PM by Alex Simmons »

Online arthwollipot

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Re: Going Solar
« Reply #95 on: October 22, 2019, 11:43:11 PM »
I'm not sure the average American knows what a granny flat is.  :D
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Online bachfiend

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Re: Going Solar
« Reply #96 on: October 23, 2019, 12:16:01 AM »
I'm not sure the average American knows what a granny flat is.  :D

Assuming that the Wikipedia is accurate, ‘secondary suite’ appears to be the American equivalent.  I’m familiar with ‘garage apartment.’  ‘Guesthouse’ is also an alternative.  Personally, I prefer ‘granny flat.’

https://en.wikipedia.org/wiki/Secondary_suite
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Online arthwollipot

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Re: Going Solar
« Reply #97 on: October 23, 2019, 01:30:32 AM »
Granny flat has a nice ring to it.
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Online Noisy Rhysling

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Re: Going Solar
« Reply #98 on: October 23, 2019, 07:08:05 AM »
My grandmother "lived on her own" into triple digits. "on her own" meant she was about ten paces from her daughter's kitchen. :laugh:
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Offline daniel1948

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Re: Going Solar
« Reply #99 on: October 23, 2019, 09:46:52 AM »
The use of "flat" to mean an apartment AFAIK is never used in the U.S. I know what it means and I assume that everyone does (though my handle on what other people know is poor to say the least). But I don't think you'd find any native U.S. American calling an apartment or separate dwelling a "granny flat." I've always understood it to be a British term. Apparently it's used elsewhere in the Commonwealth as well.

I have a cottage (a.k.a. ohana in the native Hawaiian) behind my house. It would probably be called a granny flat by someone who uses that term. I rent it out, but it would be perfect for a relative (aunt, uncle, grandmother) who wanted to be near the family while having privacy and independence.
Daniel
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Offline DevoutCatalyst

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Re: Going Solar
« Reply #100 on: October 23, 2019, 10:03:19 AM »

Online CarbShark

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Re: Going Solar
« Reply #101 on: October 23, 2019, 02:31:24 PM »
Granny flats in the going solar thread?
and Donald Trump is President of the United States.

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Offline daniel1948

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Re: Going Solar
« Reply #102 on: October 23, 2019, 03:28:06 PM »
Thread drift is normal.
Daniel
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Online arthwollipot

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Re: Going Solar
« Reply #103 on: October 23, 2019, 07:43:01 PM »
The use of "flat" to mean an apartment AFAIK is never used in the U.S. I know what it means and I assume that everyone does (though my handle on what other people know is poor to say the least). But I don't think you'd find any native U.S. American calling an apartment or separate dwelling a "granny flat." I've always understood it to be a British term. Apparently it's used elsewhere in the Commonwealth as well.

Yes, it's a pretty common term here in Australia. At least, in that part of Australia where I live. "Apartment" is rapidly becoming more common because of the all-pervasiveness of American culture, but that pretty much exclusively refers to a unit in an apartment block, not a single residence in its own building. You'll hear people of my generation and older refer to a "block of flats", but younger people mostly appear to refer to an "apartment block". "Apartment" also implies more expensive. If you're poor you'd live in a flat. If you're wealthy, you'd live in an apartment.

I have a cottage (a.k.a. ohana in the native Hawaiian) behind my house. It would probably be called a granny flat by someone who uses that term. I rent it out, but it would be perfect for a relative (aunt, uncle, grandmother) who wanted to be near the family while having privacy and independence.

Yep, that's definitely a granny flat.

Sorry for the derail, please carry on.
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Offline daniel1948

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Re: Going Solar
« Reply #104 on: October 23, 2019, 07:52:01 PM »
We also would not refer to a stand-alone house as an apartment. An apartment would be a unit within a larger building. But an apartment could be extremely small and cheap, or luxuriously large and expensive. If it's individually owned (rather than being rented from the owner of the building) then it becomes a condo, which could be large or small.
Daniel
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"Anyone who has ever looked into the glazed eyes of a soldier dying on the battlefield will think long and hard before starting a war."
-- Otto von Bismarck