I record the net meter every morning to include the overnight consumption and record the grid feed every evening after dark. At the end of the month I subtract the PV generation from the total grid feed and the difference is the total turbine grid feed. At night the system uses some grid power to maintain battery voltage and power the Sunny Island inverters, but I am only interested in total output of the generation, not total yield. For instance, total yield for 9/1 is 32.91 KWh. Total generation is 33.51 KWh. Most grid tie PV systems will not have a battery bank to maintain at night. There is one problem I am wrestling with, any turbine generation added to the total grid feed after I log the entry at dusk and before 24:00, will not be included. The only way to log this is to check the total generation at 23:59, or use the total yield from the Sunny Portal at the end of the month, which will have nightly battery maintenance deducted. If I subtract the total generation from PV for the month from the total system yield, I will have the total turbine generation minus the power used at night to maintain the battery bank at the preset voltage. For August this discrepancy is about 19 KWh, completely negating all turbine generation for the whole month. So for August my battery bank and Sunny Island inverters needed 19 KWh to maintain and keep charged up. The turbine only made a useful 16 KWh all month. Of coarse when the weather changes in winter this could be one days turbine generation.
Totals for the month of September;
Total grid feed 755.90 KWh, Total Tracker 390.10 KWh, Total fixed array 299.03 KWh. Total PV 689.13 KWh. Total turbine 66.77 KWh.
Tracker production 390.10KWh/3120W= Production factor 0.125 KWh/W/September 09.
Fixed array production 299.03KWh/2970W=Production factor 0.101 KWh/W/September 09.
Turbine production 66.77KWh/3200W=Production factor 0.021 KWh/W/September 09.
With the Solar Production Factor you can calculate how much solar PV wattage you need to install to offset your electric usage. If you need 650 KWh, then for the month of September in SE Missouri, you would need 650/0.101(fixed array)= 6.435 KW solar PV fixed array. September 09 was a poor generation month compared to August 09. This data will be better after a full year of collection. For August 09 650/0.123= 5.285 KW solar PV fixed array. After a couple more months of data I will dedicate a page to the data set spread sheet.
9/1 Net meter 999817. Total grid feed 33.51 KWh, trackers 18.58, fixed array 14.43, turbine 0.50, total PV 33.01.
9/2 Net meter 999802. Total grid feed 32.09 KWh, trackers 18.67, fixed array 13.32, turbine 0.10, total PV 31.99. It is now clear the system will generate enough power to offset my sawmill consumption. I am figuring out how to raise the money to build a new sawmill building near the net meter and move my mill to this site. The sawmill historically uses 150-350 KWh per month.
9/3 Net meter 999786. Total grid feed 25.25 KWh, trackers 14.55, fixed array 10.70, turbine 0, total PV 25.25.
9/4 Net meter 999777. Total grid feed 28.79 KWh, trackers 16.75, fixed array 12.04, turbine 0, total PV 28.79. Ran the air and baked a chicken with electric today. I have about convinced myself to get rid of the wind turbine and in it's place, utilizing the site and wire run, a dual axis tracker with about 1500 watts of solar panels. At less expense than the turbine alone, about $8,000 for equipment, we will have a great deal more generation. It will generate daily earlier and later than any other system we now have, and add any generation needed to fully run our sawmill on this site. I am simply tired of taking down the turbine over and over to fix it. And two weeks of tracker PV generation will equal 8 summer months of turbine generation.
9/5 Net meter 999771. Total grid feed 22.19 KWh. Trackers 11.716, fixed array 10.275, total PV 21.991, turbine 0.2.
9/6 Net meter 999772. Total grid feed 21.47 KWh. Trackers 11.83, fixed array 9.64, Total PV 21.47.
9/7 Net meter 999772. Total grid feed 22.66 KWh. Trackers 12.57, fixed array 10.09, total PV 22.66.
9/8 Net meter 999777. Total grid feed 21.465 KWh. Trackers 12.30, fixed array 9.065, Total PV 21.365, turbine 0.1.
9/9 Net meter 999785. Total grid feed 15.08 KWh. Trackers 7.67, fixed array 6.79, Total PV 14.46, turbine 0.62.
9/10 Net meter 999798. Here is the problem with the grid feed compiler, it seems the turbine compiler catalogued 1.89 KWh over night. History shows the turbine compiler does not reflect the true grid feed value. If I don't get up at midnight and record my grid feed, it is automatically reset to zero. So what part of the turbine recording really went into the grid before midnight? I guess I simply wait till the end of the month and use the totals to calculate overall grid feed. The energy used to maintain my batteries and operate the Sunny Island inverters which stay on all the time will stay about the same. The individual Sunny Boy inverters automatically turn off when the DC voltage drops to zero, and turn on from the morning DC voltage. Little to none AC grid power is used by them. Just another of the problems with our turbine. I have planned to take down the turbine for bearing replacement on Saturday evening 9/12. I'll loose at least a week to waiting for the replacement bearings that won't be sent till I confirm they are the source of noise. I am really tired of repairing the turbine even though the data sets are so important to prove turbines are a poor investment in this part of Missouri, even if the turbine worked all the time. Again, I would be better off replacing the turbine with PV, and hooking up the turbine's stator to a wood gas engine at ground level for emergencies. Total grid feed 29.972 KWh. Trackers 16.57, fixed array 13.12, total PV 29.69, turbine 0.28.
9/11 Net meter 999795. Total grid feed 29.12 KWh. Trackers 16.87, fixed array 12.25, total PV 29.12.
9/12 Net meter 999797. Total grid feed 30.09 KWh trackers 16.24, fixed array 12.04, total PV 28.28, turbine 2.21.
9/13 Net meter 999793. Total grid feed 26.577 KWh. Trackers 14.571, fixed array 10.81, total PV 25.381, turbine 1.2.
9/14 Net meter 999784. Total grid feed 15 KWh. Trackers 7.15, fixed array 6.67, total PV 13.82, turbine 1.18.
9/15 Net meter 999785. Total grid feed 23.82 KWh. Trackers 9.674, fixed array 8.146, total PV 17.82, turbine 6. Finally a windy day.
9/16 Net meter 999776. It has been a windy night. Total grid feed 41 KWh, trackers 14.757, fixed array 11.422, total PV 26.18, turbine 14.82. Best turbine generation in 6 months.
9/17 Net meter 999758. Total grid feed 34.73 KWh. Trackers 16.65, fixed array 12.07, total PV 28.73, turbine 6.
9/18 Net meter 999742. Total grid feed 23.567 KWh. Trackers 11.093, fixed array 8.274, total PV 19.367, turbine 4.2
9/19 Net meter 999740. Total grid feed 14.74 KWh. trackers 5.6, fixed array 4.7, total PV 10.3, turbine 4.44.
9/20 Net meter 999746. Total grid feed 8.726 KWh. Trackers 4.119, fixed array 4.007, turbine 0.6
9/21 Net meter 999761. Total grid feed 18.95 KWh. Trackers 9.9, fixed array 8.73, turbine 0.32
9/22 Net meter 999763. Total grid feed 24.52 KWh. trackers 13.794, fixed array 10.723, turbine 0. I had to run the air conditioner this evening several hours to dry out the house.
9/23 Net meter 999765. Total grid feed 13.3 KWh. trackers 7.1, fixed array 6.2 turbine 0. And again, ran the air.
9/24 Net meter 999782. Total grid feed 3.52 KWh. trackers 1.7, fixed array 1.7, turbine 0.12. total PV 3.4.
9/25 Net meter 999799. Total grid feed 33.53. trackers 18.78, fixed array 14.57, total PV 33.35, turbine 0.18.
9/26 Net meter 999786. Total grid feed 24.10. trackers 13.19, fixed array 10.231, total PV 23.42, turbine 0.68. The grid dropped out for a second today at 13:00, while I was watching a movie on Hallmark Channel. The system responded perfectly. No faults or errors. Grid feed dropped out and re synchronized, then reconnected perfectly. If these grid problems persist it is reason to switch the system over to protected power for running the house. I believe the last three weekends the grid has dropped off for a second.
9/27 Net meter 999777. Total grid feed 35.82 KWh. trackers 20.676, fixed array 14.845, total PV 35.521, turbine 0.30.
9/28 Net meter 999754. Total grid feed 55 KWh. trackers 22.1, fixed array 15.8, total PV 37.9, turbine 17.1. Record setting generation day!
9/29 Net meter 999720. Total grid feed 41.32 KWh. trackers 21.8, fixed array 15.62, total PV 37.42, turbine 3.9.
9/30 Net meter 999699. Total grid feed 36.05 KWh. Trackers 21, fixed array 15.05, Total PV 36.05.
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