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.
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Thanks,
- Win
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. 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: 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: Use the XLS spreadsheet, or XLT template under:
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.
Thanks, yes I've done that. Here's a graph showing 10 days worth of 5-minute data.
Fascinating, I didn't know about this. Thanks!!
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Thanks,
- Win
Here's some commentary on the data in the grsph.
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Thanks,
- Win
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
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.
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Thanks,
- Win
$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.
Move.
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.
Nah.
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Thanks,
- Win
I suggest you lose the colorful dots and replace them with connecting lines. It's much easier to see what's happening. I do it like this using the Enphase 5 minute data: The rather jagged curves are the result of trees, bad weather, and panels scattered all over the roof.
Well, looking at the photo of your house: I notice that the roof and panels appear to be at a 45 degree angle. When the sun is overhead, the sun angle relative to the panels is getting rather close to the Brewster Angle of 34 degrees, where much of the light is reflected from the glass. You could probably fix that by tweaking the elevation of the panels. Boston is at 42N resulting in an ideal tilt (from vertical) of 48 degrees which is close enough to the current panel tilt angle to not make it worthwhile tweaking. However, in summer, it should be more horizontal at 72 degrees. In mid winter, 24 degrees.
Incidentally, don't assume that facing south-west is a problem. Some people recommend pointing west because the electricity generated is worth more to the utility if the demand is higher in the afternoon, such as when the weather is hot:
Also, it appears that ISO New England isn't doing any solar. On the renewables pie chart: it lists wood, refuse, wind, and landfill gas, but no solar.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Is this a new definition of Brewster angle? I always thought there was zero reflection (in one polarisation) at the Brewster aengle.
John
Our local power companies are strongly opposed to solar. I've noticed the same thing elsewhere. At one point they'll go on about how solar has an undesirable mid-day peak. Elsewhere they'll go on about the special power- sourcing burden they face on hot days when everyone turns up their air conditioning, without admitting that the concurrent solar peak helps to ameliorate that burden.
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Thanks,
- Win
Are you sure? It seems like Mass has a fair number of solar power related companies.
The real problem is that home solar users require that the local utilities upgrade their lines and equipment to handle the extra capacity. Most of the existing equipment seems to be operating at about 90% of capacity. Since the utility has little control over the distribution of home power generation, it could easily become a system wide upgrade. Also, the utility is expected to invest in energy storage facilities, which tend to be expensive. As always, just follow the money.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
The main cause of price increases are due to the reducing demand from infrastructure that has fixed ongoing costs. As prices increase, folk reduce their usage, which compounds the problem.
The more electricity that's generated by solar (or wind, for that matter), the more unstable the grid becomes. No, power companies don't like that.
The rosy solar situation in MA is entirely due to the public sentiment and the state legislature. The power companies are strongly against it. Last year they developed enough influence to keep the legislature from renewing the incentives, and the 2015 session ended with expired incentives, and no renewal. It took 5 months, IIRC, into 2016 to get the renewal, which then included a severe downgrading of some of the important initiatives, killing deals underway.
This claim is I think is completely bogus. At our present scale, and far beyond, there's no question that locally-generated solar power is, and will be, completely used locally, reducing, not increasing the electrical load on wiring infrastructure. What it does do is stress the economics of the coal and gas-fired power plants that aren't able to sell as much power as they'd like during that prime time.
I don't think power companies need storage anytime soon, but it's certainly on the horizon, and the solar-generating folks should chip in their fair share. I'm planning on some investment myself.
You didn't bring up the issue of net metering. In a non-incentivized system, what's the proper price for a solar producer to pay for the grid?
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Thanks,
- Win
On Sep 8, 2016, Winfield Hill wrote (in article ):
Germany is way ahead of the US on Solar and Wind power, and it has _not_ been a bed of roses.
There have been some series of articles in Der Spiegel, which has an online-only English-language service. What got to me were the grumbles that Energiewande (Energy Transition / Revolution) was going to de-industrialize Germany. Mainly because the electric rates had tripled as a consequence of the intermittent / unsteady nature of Solar and Wind power.
.Here are some relevant articled from Der Spiegel (The Mirror). Der Spiegel is the Economist of Germany, with a dash of Newsweek.
.Part 1 of
7 parts - see bottom for links. Part 4 quotes a particularly wry point about ice cream. .The German political center is Social Democratic, in US terms this being much closer to the Democratic Party than the Republican Party.
Joe Gwinn
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One way they can make sure that the street is not a net generator of power is to set the transformer tap very close to the maximum legal voltage. Then if people start generating rather than consuming power on average, the inverters will sense that the maximum voltage is exceeded and shut down. I don't think they will admit to delibertely doing that here, but the voltage overnight here is certainly very close to the upper limit, and never ever gets anywhere near the lower limit regardless of weather or time of day.
There's nothing unstable about solar or wind power generation, but the leve l of power available is only predictable in the short term.
The power companies don't like firing up their gas-turbine driven generator s at short notice to fill in the gaps. They'd much prefer to keep the coal- fired generators running all the time. There are forms of despatchable sola r-powered generation - thermal solar can dump the solar heat into molten sa lt and leave it there for a day or so (longer with even bigger tanks of mol ten salt) before using it to heat steam to drive a steam turbine - and in t he long time we'll find a practical form of battery storage.
The grid certainly doesn't become "unstable", but it does have to be manage d more carefully. The upside is that if a lot of your power is being genera ted locally, the grid doesn't have to carry it as far, and transmission los ses go down.
-- Bill Sloman, Sydney
It isn't only "selling power".
Considering generation and consumption across a wide area like the UK, if you install 1GW of wind or solar generating capacity, then you can reduce the capacity of conventional generating plant by 0.0GW. If you get a "blocking high" sitting over the UK, then there is effectively zero wind output for quite a few days at a time. Unsurprisingly, solar eclipses have interesting effects on solar output.
In addition thermal plants prefer constant load and dislike being thermally shocked by ramping their output up and down.
That implies the conventional plant will be running less /economically/ efficiently, and will therefore appear more expensive.
Large-scale energy storage will be a game-changer. Personally I don't believe in battery storage due to the finite number of charge-discharge cycles.
What technology might you invest in?
On Sep 8, 2016, Clifford Heath wrote (in article):
Another good Der Spiegel reference:
This is the article with the ice cream reference and talk of deindustrialization.
Joe Gwinn
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