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tinyurl.com/TeslaKauai
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contact:
matthew.klippenstein@gmail.com
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created for article:
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https://www.solaranywhere.com
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Approximate coordinates 21.95°N, 159.35°W.
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Raw Data tab:
This tab contains the "representative year" of solar data.
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Date columnDay/month/year from which the representative data was taken.
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Time column
Time of day, in hourly increments. These periods are one-hour increments finishing at the stated time.
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e.g. 1:00 means the one-hour increment from 12:00:01 to 1:00:00
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GHI (W/m2)
Global Horizontal Irradiance. In lay terms, how much sunlight will hit the solar panels during a given period.
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Note that no sunlight hits the panels when the sun's not up (e.g. late night / early morning)
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Also note that the numbers reported are averaged for the 1-hour period, so though GHI has units of W/m2...
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...since the time period is 1 hour, then these figures can als be said to measure GHI in units of W-h/m2.
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Crunched GHI data:
Hopefully this is reasonably easy to understand
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Columns A-CDirectly copied from the "Raw Data" tab.
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Columns D-EWe extract the month and date from the date-stamp in column A.
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We can then use that information to calculate the GHI on each day of the year, in column J.
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Crunching Daily GHI data:
Further calculations leveraging the Crunched GHI data sheet.
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Columns A-CDay of year and GHI data from the prior tab.
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Column D
Capacity factor based on assumption of maximum of 1 kWh/m2/h GHI (or 24 kWh/m2/day).
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Column F
Expected electricity production on that day of the year, given the amount of GHI. DC basis (at the solar panel)
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Column G
Expected electricity production on that day of the year. AC basis (at the grid)
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Column K
Equals the lesser of Column G or 52 MWh (the maximum Tesla is allowed to provide the grid each evening)
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Columns N-P
Calculates the daily average energy to the grid in year 1, if the extra "buffer" of 5 MWh of batteries are used to "top up" grid contributions on cloudy/rainy days.
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Columns S-Y
Calculates the daily average energy to the grid in year 20, based on estimates of solar and battery degradattion.
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Calculations are made for situations where the extra "buffer" is not used (45 MWh) and where it is used (49 MWh).
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Powerwall Efficiency:
Outlines assumptions made on Powerwall / Powerpack efficiency at transforming DC inputs to AC outputs.
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Outlines assumptions made for solar panel degradation over the 20 year period.
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Outlines assumptions made for battery pack degradation over the 20 year period.
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DCF calculation:
Outlines how the Discounted Cash Flow (DCF) calculations were made.
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