Difference between revisions of "Load and solar resource comparison"

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[[Category:Site evaluation]]
 
[[Category:Site evaluation]]
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The design process for an off-grid PV system should use conservative, worst-case values to ensure that the system is capable of meeting the energy needs of users throughout the year. There are many locations that have a significant seasonal variance in [[Special:MyLanguage/Weather and solar resource evaluation|solar resource]] due to poor weather or latitude. Many off-grid PV systems will see a significant variance in [[Special:MyLanguage/Load evaluation|how loads are used throughout the year]], especially in locations that are only seasonally occupied. These two different factors - load usage vs. solar resource - make it important to determine what month to use in the system design as the worst-case scenario. An analysis of loads and usage could be performed on a monthly basis, but the most drastic shift in usage likely occurs between the major seasons in a given region meaning two times per year. Determining the worst-case month can be done using a simple table and a quick calculation using [[Special:MyLanguage/Weather and solar resource evaluation|monthly insolation data]] and [[Special:MyLanguage/Load evaluation|Average daily Wh estimates]] for the two different time periods October - March and April - September. The two following values used for the design should be chosen from the month with the highest ratio of average daily watt-hours relative to average monthly insolation:
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*Design daily insolation
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*Design daily watt-hours required
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====Step 1: Determine monthly ratio of energy demand to solar resource==== <!--T:4-->
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{| class="wikitable" border=1
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!Month
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![[Special:MyLanguage/Weather and solar resource evaluation#Solar resource (insolation)|Average monthly insolation (kWh/m²)]]
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![[Special:MyLanguage/Load evaluation#Total average daily energy demand|Total average daily energy demand (Wh)]]
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!Ratio
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|January
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*'''Month:''' The month of the year.
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*'''Average monthly insolation:''' Solar resource data obtained for the location from [[Special:MyLanguage/Weather and solar resource evaluation|Weather and solar resource evaluation]].
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*'''[[Special:MyLanguage/Load evaluation#Total average daily energy demand|Total average daily energy demand]]''' for the month from the load evaluation.
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*'''Ratio =''' Total average daily energy demand ÷ Average monthly insolation
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====Step 2: Determine design values==== <!--T:9-->
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{| class="wikitable" border=1 style="width: 80%;"
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! style="width: 20%"|Design daily insolation
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! style="text-align:left;"| = Average monthly insolation (kWh/m²) from month with the highest ratio ÷ 30
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|}
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{| class="wikitable" border=1 style="width: 80%;"
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! style="width: 20%"|Design daily watt-hours required
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! style="text-align:left;"| = Total average daily energy demand (Wh) from month with the highest ratio
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|}
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==Notes/references== <!--T:12-->
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<references/>
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</translate>

Latest revision as of 14:19, 1 April 2021

Other languages:
English • ‎español

The design process for an off-grid PV system should use conservative, worst-case values to ensure that the system is capable of meeting the energy needs of users throughout the year. There are many locations that have a significant seasonal variance in solar resource due to poor weather or latitude. Many off-grid PV systems will see a significant variance in how loads are used throughout the year, especially in locations that are only seasonally occupied. These two different factors - load usage vs. solar resource - make it important to determine what month to use in the system design as the worst-case scenario. An analysis of loads and usage could be performed on a monthly basis, but the most drastic shift in usage likely occurs between the major seasons in a given region meaning two times per year. Determining the worst-case month can be done using a simple table and a quick calculation using monthly insolation data and Average daily Wh estimates for the two different time periods October - March and April - September. The two following values used for the design should be chosen from the month with the highest ratio of average daily watt-hours relative to average monthly insolation:

  • Design daily insolation
  • Design daily watt-hours required

Step 1: Determine monthly ratio of energy demand to solar resource

Month Average monthly insolation (kWh/m²) Total average daily energy demand (Wh) Ratio
January
February
March
April
May
June
July
August
September
October
November
December
  • Month: The month of the year.
  • Ratio = Total average daily energy demand ÷ Average monthly insolation

Step 2: Determine design values

Design daily insolation = Average monthly insolation (kWh/m²) from month with the highest ratio ÷ 30
Design daily watt-hours required = Total average daily energy demand (Wh) from month with the highest ratio

Notes/references

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