(Topic ID: 337796)

Any Pinsiders have solar panels? What are your experiences?

By ImNotNorm

1 year ago


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  • Latest reply 40 days ago by ImNotNorm
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    There are 109 posts in this topic. You are on page 3 of 3.
    #101 42 days ago

    My stats for this morning. My last three bills have just been for connection charges. (~$15 US)

    The system went live Dec 28, 2023 - 10KWh

    Current Power5.95 kW

    Energy today5.54 kWh

    Energy this month204.62 kWh

    Lifetime energy6.44 MWh

    My array (resized).pngMy array (resized).png
    #102 42 days ago
    Quoted from ImNotNorm:

    I'd love to hear the details. Especially if it's a different jurisdiction like SUN CITY, Arizona!!
    But I'm curious what your system size is in terms of actual per hour generation.
    You said 25,000KwH/annually...so quick math would approximate you have a 3.0KwH system?
    Mine is 6.5 KwH system. The max I could ever harness if all the cells are at max exposure is 6.5KwH of energy for that 1 hour. (which will never happen)
    [quoted image]

    You have a 6.5kW system, not a 6.5kWh system. Generating 25,000kWh/yr (25mWh) is probably more in the range of a 15-18kW system or 3x-4x panel capacity compared to yours. kWh is a function of energy over time. kW is a measure of energy.

    I have a 14.8kW system ground mount system with no obstruction and I average around 22,000kWh/yr in Maryland.

    #103 42 days ago
    Quoted from justler:

    You have a 6.5kW system, not a 6.5kWh system. Generating 25,000kWh/yr (25mWh) is probably more in the range of a 15-18kW system or 3x-4x panel capacity compared to yours. kWh is a function of energy over time. kW is a measure of energy.
    I have a 14.8kW system ground mount system with no obstruction and I average around 22,000kWh/yr in Maryland.

    Thanks for the correction/clarification.

    #104 41 days ago
    Quoted from ImNotNorm:

    I'd love to hear the details. Especially if it's a different jurisdiction like SUN CITY, Arizona!!
    But I'm curious what your system size is in terms of actual per hour generation.
    You said 25,000KwH/annually...so quick math would approximate you have a 3.0KwH system?
    Mine is 6.5 KwH system. The max I could ever harness if all the cells are at max exposure is 6.5KwH of energy for that 1 hour. (which will never happen)
    [quoted image]

    I have lots of details and now with about 8 months of data. But the real test is starting now as we start the summer months. The Phoenix area of course is somewhat notorious as one of the hottest (if not the hottest) places in the US. The first streak of 100F/38C + days has started, with 10 days in a row, and hitting 109F/43C yesterday.

    The real test as far as investment return is the ability of the solar system to keep up with the AC demand. And, it must be noted, having long, hot, sunny days does not translate to the best power generation. This is because these solar panels have a temperature efficiency curve, and the maximum efficiency occurs somewhere around 80F/27C or so. So when the panels get very hot, the efficiency drops a bit. The company I bought from had told me that May was the optimal month for max production, and so far the data supports that.

    My system is what they call a 15.6kW setup. This math is straightforward: There are 39 400W panels, so 39*400=15,600 W or 15.6kW.

    For a look at production in one hour, the theoretical maximum would be 15.6kW. However, in practicality this is not achieved due to a number of factors including things like location of the panels, tilt of the panels, where the install is located, and of course clouds, dust in the sky, and so on. It turns out that for my system, the max for an hour is 11.5W.

    You can see this here, in the solar panel app I can slide over any time of the day and see what that max output was.
    2024-05-19 output hour max (resized).jpg2024-05-19 output hour max (resized).jpg

    Here is that plot again, and this is from May 19, which so far is the highest producing day. As noted, the total production for that day was 99.5 kWh.

    2024-05-19 output (resized).jpg2024-05-19 output (resized).jpg

    You will see that there is a "clipping" effect, where everything levels off at 11.5kW max output while the sun is at its highest. I did some looking into the documentation I have then I called the solar company to confirm my idea. My setup is configured with microinverters, rather than one inverter box that takes care of converting the DC voltage output of the panels to AC. So there are 39 microinverters, one for each panel. It turns out that the microinverters have a peak output of 300W, so if you multiply 39*300 you get 11.7kW. The 0.2kW loss is due to environmental factors and such. The explanation was that this is the most efficient setup for the money. It is possible to get microinverters with higher output, but they are more costly. He also noted that I was only the second customer they have had who thought about this and asked about it. As I told him, I get somewhat picky when I spend that kind of money and I love to make spreadsheets, so I am tracking everything I can think of as this system is in production. Also, it is just my nature to want to know exactly how such things work (such as the borderline-insane posts about the workings of my pinball machines).

    So one thing to know is that its not just the panels that determine the overall efficiency, it is the system as a whole, and the inverters that are required do cause some loss.

    I can also look at another screen in the app to see all of the individual panels. This can be done in real time during the day, or for a past date such as here, again for May 19. Here you can see how much each panel produced for the day to confirm they are all working as expected.

    That's some solar fun for now, I have lots more data if anyone is interested or has some questions.
    2024-05-19 output arrays (resized).jpg2024-05-19 output arrays (resized).jpg

    #105 41 days ago
    Quoted from loneacer:

    Financially I suspect you'd come out ahead by investing the money and using the proceeds from the investments to pay your electric bill. The concept of having more reliable power is nice, but I know several people that have gotten them installed and regretted it. Some day solar panels might be cheap enough to make sense, but I think we're a long way off.

    Depends on where you live, how much power you use, and how much power you produce. I installed a system currently producing approximately 115% of my annual usage. Assuming an average stock market return of 8%, solar was by far a better investment. I will still be in a 90% (+/-) offset production in 20 years, maybe less depending on total panel degradation and increased energy use. Summers are being hotter and hotter where I live which means more electricity use to keep cool. Electricity is only going to be more expensive everywhere as time marches on. I have converted my entire property to electric. No more gas for cooking, heating, or hot water. I keep everything at temperatures that I find comfortable without thinking about a power bill. If you have the means, are committed to where you live, and have good southern exposure solar is a no brainier.

    #106 41 days ago
    Quoted from xsvtoys:

    I have lots of details and now with about 8 months of data. But the real test is starting now as we start the summer months. The Phoenix area of course is somewhat notorious as one of the hottest (if not the hottest) places in the US. The first streak of 100F/38C + days has started, with 10 days in a row, and hitting 109F/43C yesterday.
    The real test as far as investment return is the ability of the solar system to keep up with the AC demand. And, it must be noted, having long, hot, sunny days does not translate to the best power generation. This is because these solar panels have a temperature efficiency curve, and the maximum efficiency occurs somewhere around 80F/27C or so. So when the panels get very hot, the efficiency drops a bit. The company I bought from had told me that May was the optimal month for max production, and so far the data supports that.
    My system is what they call a 15.6kW setup. This math is straightforward: There are 39 400W panels, so 39*400=15,600 W or 15.6kW.
    For a look at production in one hour, the theoretical maximum would be 15.6kW. However, in practicality this is not achieved due to a number of factors including things like location of the panels, tilt of the panels, where the install is located, and of course clouds, dust in the sky, and so on. It turns out that for my system, the max for an hour is 11.5W.
    You can see this here, in the solar panel app I can slide over any time of the day and see what that max output was.
    [quoted image]
    Here is that plot again, and this is from May 19, which so far is the highest producing day. As noted, the total production for that day was 99.5 kWh.
    [quoted image]
    You will see that there is a "clipping" effect, where everything levels off at 11.5kW max output while the sun is at its highest. I did some looking into the documentation I have then I called the solar company to confirm my idea. My setup is configured with microinverters, rather than one inverter box that takes care of converting the DC voltage output of the panels to AC. So there are 39 microinverters, one for each panel. It turns out that the microinverters have a peak output of 300W, so if you multiply 39*300 you get 11.7kW. The 0.2kW loss is due to environmental factors and such. The explanation was that this is the most efficient setup for the money. It is possible to get microinverters with higher output, but they are more costly. He also noted that I was only the second customer they have had who thought about this and asked about it. As I told him, I get somewhat picky when I spend that kind of money and I love to make spreadsheets, so I am tracking everything I can think of as this system is in production. Also, it is just my nature to want to know exactly how such things work (such as the borderline-insane posts about the workings of my pinball machines).
    So one thing to know is that its not just the panels that determine the overall efficiency, it is the system as a whole, and the inverters that are required do cause some loss.
    I can also look at another screen in the app to see all of the individual panels. This can be done in real time during the day, or for a past date such as here, again for May 19. Here you can see how much each panel produced for the day to confirm they are all working as expected.
    That's some solar fun for now, I have lots more data if anyone is interested or has some questions.
    [quoted image]

    Does your system have batteries to store your excess power ? If you still have excess power does your provider buy it or give you credit ?

    #107 41 days ago
    Quoted from Pinball_Postal:

    Does your system have batteries to store your excess power ? If you still have excess power does your provider buy it or give you credit ?

    These things are variables that will depend on your jurisdiction and even your specific power company, so research needs to be done when considering solar.

    I don’t have any batteries in my setup. There are scenarios where batteries may be desirable, such as when the provider proves to be unreliable and long outages are not uncommon. The power seems to be pretty reliable here so batteries are not commonly used. It may also be an issue here in Arizona where the summer heat is absolutely brutal and tends to destroy almost everything, I can’t imagine it would be too good for a solar battery system. The main disadvantage is that battery systems are pretty expensive, and add lots of thousands of dollars to the initial cost of the system.

    In my case I have a grid tied system, which is somewhat common and means the solar system is tied to the electrical grid. Additionally, the electricity provider APS here in Arizona does offer what they call solar export credit. This means that for any time the panels are producing more power than the house is using, it will be fed back to the grid, and I get paid for it.

    The payment per kWh for solar export is a lot less than the rate you pay, but it does add up. The rate is based on approved schedules that they put in place and these rates can change. Currently I get paid 7.619 cents per kWh I feed into the grid.

    It is a bit difficult to come up with electricity costs per kWh because of all of the different surcharges and rates on the utility bill, and the total amount you use per month affects those rates with increasing levels of cost for higher levels of consumption. Based on my best calculations the overall rate I pay for electricity is right around 18 cents.

    On a typical all-sunny day topping out at 100F the system will produce about 98 kWh. About 65 KWh of that will be exported to the grid, which means I used about 33 kWh during that time. For the 24 hour day, a typical supply from the provider is about 18 kWh, that would be for all of the electricity used at night, or for any time the panel output wasn’t enough supply. So, about 50 kWh total use of electricity for the day.

    With those numbers, the final cost per day is something around -$1.50, using 7.6 cents rate for the export and 18 cents for the power from the provider. My April-May bill was -$50.63.

    We are just getting to the real meat of summer so soon I will have more data for the 110+ F days. That’s when the AC starts getting a real workout. I don’t think such favorable overall rates will hold up but we’ll see.

    There are 2 AC units (heat pumps actually) for the house. There is also a swimming pool so that filtration system also runs 8 hours/day.

    If you don’t have good AC and access to a pool in this place, you will literally die

    #108 40 days ago

    OK,we talk about Batteries,well,if you have a heat pump, forget about a battery backup! Batteries as of now, will only power that heat pump for a couple of hours! I use a solar panel and a Generac whole home generator with a 500 lb propane tank!

    #109 40 days ago

    Good information guys!

    Like you xsvtoys , I'll have a more accurate picture of my system/data after the summer where it'll be operating for 1 full year.

    I also signed up for the Solar club and began that in March.
    It's basically a carbon offset program so big polluters can pay for renewable credits to "offset" their emissions.

    So...during the months where I generate more than I use, I buy/sell each kwh for $0.30 cents. (Approximately April through Oct)

    When I generate less than I use, I buy/sell each kwh for $0.11 cents. (Nov through Mar)

    These rates are locked in for 3 years and I'm able to change between the high/low rates anytime I want with no fees or penalties. My negative bills carry over month after month and if I have a credit by the end of the year they'll just cut me a check.

    My last bill was -$35

    With that said, the solar club program could come to an end at anytime. But I really don't see that happening for a while....but who really knows. If that does occur I'll just resort to buying and selling for the same price per kwh year round.

    Additionally, we rarely use lights in the house during the summer. (Basement primarily)
    And we turn on our A/C for maybe 2 months. (No pool or hot tub)

    Last month we used 205kwh.

    And prior to our system installation, they looked at our power bills from the previous year to estimate how large our system needed to be.
    But we didn't tell them we had two houses on the go for 1/4 of that years worth of power bills. So I'm estimating we will over generate annually.
    Screenshot_20240608_153341_Adobe Acrobat~3.jpgScreenshot_20240608_153341_Adobe Acrobat~3.jpg
    Screenshot_20240608_153336_Adobe Acrobat~3.jpgScreenshot_20240608_153336_Adobe Acrobat~3.jpg

    There are 109 posts in this topic. You are on page 3 of 3.

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