View source for Load and solar resource comparison/en

[[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:

*Design daily insolation

*Design daily watt-hours required

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

{| class="wikitable" border=1
!Month
![[Special:MyLanguage/Weather and solar resource evaluation#Solar resource (insolation)|Average monthly insolation (kWh/m²)]]
![[Special:MyLanguage/Load evaluation#Total average daily energy demand|Total average daily energy demand (Wh)]]
!Ratio
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|January
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|February
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|March
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|April
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|May
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|June
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|July
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|August
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|September
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|October
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|November
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|December
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*'''Month:''' The month of the year.

*'''Average monthly insolation:''' Solar resource data obtained for the location from [[Special:MyLanguage/Weather and solar resource evaluation|Weather and solar resource evaluation]].

*'''[[Special:MyLanguage/Load evaluation#Total average daily energy demand|Total average daily energy demand]]''' for the month from the load evaluation.

*'''Ratio =''' Total average daily energy demand ÷ Average monthly insolation

====Step 2: Determine design values====

{| class="wikitable" border=1 style="width: 80%;"
! style="width: 20%"|Design daily insolation 
! style="text-align:left;"| = Average monthly insolation (kWh/m²) from month with the highest ratio ÷ 30
|}

{| class="wikitable" border=1 style="width: 80%;"
! style="width: 20%"|Design daily watt-hours required
! style="text-align:left;"| = Total average daily energy demand (Wh) from month with the highest ratio
|}

==Notes/references==
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