What will a solar system this size do?

Discussion in 'Bad Dog Cafe' started by teleman1, Mar 29, 2020.

  1. Obsessed

    Obsessed Telefied Ad Free Member

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    Okay, I have heard that nomenclature of Kilowatthours enough times and it still makes no sense to me. Watts are watts, but nevertheless, I should get used to it. Thanks for clearing it up for me anyway, I really do appreciate it. I enjoy my independence from fossil fuels as much as possible, which is priceless to me. The 12 cents per kilowatt hour comes with too many strings for me and since I designed and installed my own system, it paid off about 18 years ago. Of course I do have the most expensive 12VDC ref/freezer made.:rolleyes::lol:
     
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  2. TeleTucson

    TeleTucson Tele-Afflicted

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    Hi Obsessed - I feel your pain. Your unit of "100 watts/hour" is like an acceleration of energy, something we could all use about now.

    The terminology is perhaps confusing but the idea is really simple if you take just a moment to understand what it is saying.

    Think about what is being measured -- either it is measuring a quantity or quantity per unit time. Like miles, and miles per hour.

    The quantity is energy. A Watt is not a measure of energy, it is a measure of energy per unit time. A Kilowatt is just a thousand times more energy per unit time than a Watt. If you want to know the energy delivered in some given interval of time, you just multiply the (energy per unit time) by the (time interval). Easy, right? So a Kilowatt-hour is the amount of energy coming at a rate of a thousand Watts that is delivered in a time interval of one hour.

    If we need to get nerdy, the relevant unit of energy here is called a "Joule" and a Watt is defined as one Joule per second. So a Kilowatt-hour is a rate times a time interval, and specifically it is 1000 Joules/sec X 3600 seconds = 3.6 million Joules. Here 3600 is the number of seconds in one hour.

    We could have a long thread about converting between units, such as calories, or the food calorie (which is actually a kilocalorie), or BTU's which is another measure of energy (for example, 1 BTU is 1055.06 Joules). What fun.
     
    Last edited: Mar 31, 2020
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  3. scooteraz

    scooteraz Friend of Leo's

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    LOL, when I saw the OP, I thought “fly through space at the edge of the galaxy at incredible speed....”
     
  4. kafka

    kafka Tele-Afflicted

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    I just sold a house with a solar service contract. Man, what a nuisance.

    The contract itself was no big deal. Energy would be cheaper than local terrestrial power. The savings comes because of the elimination of distribution and transmission expenses. Very easy to demonstrate against the rate schedule. Zero additional costs, the solar company handles all maintenance and removal of the system at the end of the contract, with restoration of the roof. Very straightforward.

    But getting people to even look at, let alone understand the contract was another matter entirely. When selling a house, you don't want a leased system attached to the sale, at all, whether it's a solar panel, or a security system, or whatever. It's just not worth the hassle. It simply reduces the number of potential buyers to the ones who can read and do arithmetic. And among them, the fact that the buying pool is reduced invites a lot of low-ballers who waste your time.

    Now, in the end, I ended up with a buyer who understood the contract, and the sale was straightforward. Transfer of the contract was trivial. My buyer really liked the idea of walking into a 90% efficient house. It actually did turn into a selling point. But, I could have sold the house earlier without the contract.

    I'd put some panels on our new house, but we have a lot of trees, and there just isn't any liklihood that I'd be able to generate enough power to pay for them. The trees are actually more energy efficient, because we hardly had the AC on at all last summer, and only when we had guests over. If I lived in a state with a lot of sun, it would be a no-brainer. Even so, I'd just buy them outright, and wouldn't touch a lease.
     
    Last edited: Mar 30, 2020
  5. Buckocaster51

    Buckocaster51 Super Moderator Staff Member Ad Free Member

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    Here’s my production for the day. It is a “9.8kW” collector. My March utility bill came today. The utility owes me money.

    Questions?

    B2C2970A-B771-4DC1-B5E6-E667854C3741.jpeg
     
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  6. Blue Bill

    Blue Bill Poster Extraordinaire

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    TT, thanks for the backup! I noticed yesterday, that even some .gov info sites have kWH confused with kW. Nice explanation.

    3uqilv.jpg
     
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  7. Buckocaster51

    Buckocaster51 Super Moderator Staff Member Ad Free Member

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    I’m at about 42 degrees N

    December was not quite this good

    July will be better

    We have a humid, continental climate

    For the year we will have made more than we used.

    Payback will be well less than 7 years.
     
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  8. Buckocaster51

    Buckocaster51 Super Moderator Staff Member Ad Free Member

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    Back when I was doing Physics, I became almost anal about maintaining the integrity of my units.

    If the units work out, you know your results are at least barking up the right tree. ;)
     
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  9. TeleTucson

    TeleTucson Tele-Afflicted

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    Yes, referred to as "dimensional analysis" - it even sometimes helps you capture some constants that separate regimes of behavior in physical systems, like the "Reynolds number" in fluid mechanics. If your dimensions don't work out, you left something out and better go back to square one!
     
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  10. Obsessed

    Obsessed Telefied Ad Free Member

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    Thanks for trying to jog my brain about this. As a retired mechanical engineer, electrical was where I did not do too well in college.:oops: I built my own micro hydro and I suppose the units of measurement seems logical, but I look at my amp meter while my alternator is spinning, so in my mind I see "water" flowing through a "pipe" at a certain rate. Building the gravity pipe line to my hydro plant while designing in friction loss over a distance just like electricity loss through a wire, I measure 50 gallons per minute through the nozzles. I can place a bucket and catch that 50 gallons and see it, hold it, carry it and dump it. This is how I look at 100 watts per hour. Is this incorrect or am I just getting confused by nomenclature? o_O I appreciate you guys trying to help me get this right in my head.:)
     
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  11. Obsessed

    Obsessed Telefied Ad Free Member

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    Mine would be a flat line at 0.1 ... for 24 hours though.:D
     
  12. TeleTucson

    TeleTucson Tele-Afflicted

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    Please read my post once more! The Watts is not something in a bucket. Energy is what's in the bucket, the Watts is like a measure of how fast the water flows in the picture you're using. So in your version of the water analogy, Watts is more like GPM, and energy (Joules, Calories, BTU's, KW-hrs, etc.) is like gallons.

    The water analogy can be much more precise, in which case you need to introduce pressure. Then GPM is actually more rigorously analogous to current (amps), and pressure is like voltage, and power (like Watts) is actually proportional to pressure X GPM just like power in electrical is voltage X current. But we don't need to go there for this discussion.

    The main confusion you need to get over is that Watts is not the thing, it is the rate of the thing. Just like MPH is not the thing -- miles is the thing, and MPH is the rate!
     
    Last edited: Apr 1, 2020
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  13. 1293

    1293 Poster Extraordinaire

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    Peanut butter is delicious. I lost interest four posts in.
     
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