Difference between revisions of "Load and solar resource comparison"
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[[Category:Site evaluation]] | [[Category:Site evaluation]] | ||
| − | 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 [[Weather and solar resource evaluation|solar resource]] due to poor weather or latitude. Many off-grid PV systems will see a significant variance in [[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 to four times per year. Determining the worst-case month can be done using a simple table and a quick calculation. The values and calculation can be performed in Wh or kWh - the ratio is what is important. 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 insolation: | + | 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 [[Weather and solar resource evaluation|solar resource]] due to poor weather or latitude. Many off-grid PV systems will see a significant variance in [[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 to four times per year. Determining the worst-case month can be done using a simple table and a quick calculation. The values and calculation can be performed in Wh or kWh - the ratio is what is important. 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 insolation | + | *Design daily insolation |
*Design daily watt-hours required | *Design daily watt-hours required | ||
| − | '''Example 1:''' A potential off-grid PV system in Puerto Maldonado, Madre de Dios, Peru in the Amazon rainforest with [[PV module|PV source]] with a tilt of 12 degrees of PV module tilt. Solar resource data shows that despite being relatively near the equator there is significant monthly variation due to seasonal rains.<ref name=" | + | '''Example 1:''' A potential off-grid PV system in Puerto Maldonado, Madre de Dios, Peru in the Amazon rainforest with [[PV module|PV source]] with a tilt of 12 degrees of PV module tilt. Solar resource data shows that despite being relatively near the equator there is significant monthly variation due to seasonal rains.<ref name="pvgis"> EU PVGIS https://re.jrc.ec.europa.eu/pvg_tools/en/#MR</ref> The load evaluation shows that loads will be used more frequently during the rainy season, which is common. |
| − | * | + | *May (highlighted in red) has the worst ratio of solar resource relative to energy requirement throughout the year. The average monthly insolation value (135.47 kWh/m²) and Average daily Watt-hours required (3000Wh) from this month should be used in the design. |
{| class="wikitable" border=1 | {| class="wikitable" border=1 | ||
| Line 15: | Line 15: | ||
|- | |- | ||
|January | |January | ||
| − | | | + | |147.27 kWh/m² |
|2000 Wh | |2000 Wh | ||
| − | | | + | |13.58 |
|- | |- | ||
|February | |February | ||
| − | | | + | |140.08 kWh/m² |
|2000 Wh | |2000 Wh | ||
| − | | | + | |14.28 |
|- | |- | ||
|March | |March | ||
| − | | | + | |166.77 kWh/m² |
|2000 Wh | |2000 Wh | ||
| − | | | + | |11.99 |
|- | |- | ||
|April | |April | ||
| − | | | + | |161.56 kWh/m² |
| − | | | + | |3000 Wh |
| − | | | + | |18.57 |
| − | |- | + | |- style="background-color:#F08080;" |
|May | |May | ||
| − | | | + | |135.47 kWh/m² |
| − | | | + | |3000 Wh |
| − | | | + | |22.15 |
|- | |- | ||
|June | |June | ||
| − | | | + | |157.44 kWh/m² |
|3000 Wh | |3000 Wh | ||
| − | | | + | |19.05 |
| − | |- | + | |- |
|July | |July | ||
| − | | | + | |149.74 kWh/m² |
|3000 Wh | |3000 Wh | ||
| − | | | + | |20.03 |
|- | |- | ||
|August | |August | ||
| − | | | + | |178.82 kWh/m² |
|3000 Wh | |3000 Wh | ||
| − | | | + | |16.78 |
|- | |- | ||
|September | |September | ||
| − | | | + | |172.36 kWh/m² |
|3000 Wh | |3000 Wh | ||
| − | | | + | |17.41 |
|- | |- | ||
|October | |October | ||
| − | | | + | |170.63 kWh/m² |
| − | | | + | |2000 Wh |
| − | | | + | |11.72 |
|- | |- | ||
|November | |November | ||
| − | | | + | |161.02 kWh/m² |
|2000 Wh | |2000 Wh | ||
| − | | | + | |12.42 |
|- | |- | ||
|December | |December | ||
| − | | | + | |164.17 kWh/m² |
|2000 Wh | |2000 Wh | ||
| − | | | + | |12.18 |
|} | |} | ||
*'''Month:''' The month of the year. | *'''Month:''' The month of the year. | ||
*'''Average daily insolation:''' Solar resource data obtained for the location from [[Weather and solar resource data sources]]. | *'''Average daily insolation:''' Solar resource data obtained for the location from [[Weather and solar resource data sources]]. | ||
*'''[[Load evaluation#Average daily watt-hours required|Average daily watt-hours required]]''' from load evaluation. | *'''[[Load evaluation#Average daily watt-hours required|Average daily watt-hours required]]''' from load evaluation. | ||
| − | *'''Ratio =''' Average daily watt-hours required ÷ Average daily insolation | + | *'''Ratio =''' Average daily watt-hours required ÷ Average monthly insolation |
| + | |||
| + | ==Outputs== | ||
| + | |||
| + | {| class="wikitable" border=1 style="width: 80%;" | ||
| + | ! style="width: 20%"|Design daily insolation | ||
| + | ! style="text-align:left;"| = Average monthly insolation 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;"| = Average daily watt-hours from month with the highest ratio | ||
| + | |} | ||
==Notes/references== | ==Notes/references== | ||
<references/> | <references/> | ||
Revision as of 09:53, 19 December 2020
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 to four times per year. Determining the worst-case month can be done using a simple table and a quick calculation. The values and calculation can be performed in Wh or kWh - the ratio is what is important. 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
Example 1: A potential off-grid PV system in Puerto Maldonado, Madre de Dios, Peru in the Amazon rainforest with PV source with a tilt of 12 degrees of PV module tilt. Solar resource data shows that despite being relatively near the equator there is significant monthly variation due to seasonal rains.[1] The load evaluation shows that loads will be used more frequently during the rainy season, which is common.
- May (highlighted in red) has the worst ratio of solar resource relative to energy requirement throughout the year. The average monthly insolation value (135.47 kWh/m²) and Average daily Watt-hours required (3000Wh) from this month should be used in the design.
| Month | Average daily insolation | Average daily watt-hours required | Ratio |
|---|---|---|---|
| January | 147.27 kWh/m² | 2000 Wh | 13.58 |
| February | 140.08 kWh/m² | 2000 Wh | 14.28 |
| March | 166.77 kWh/m² | 2000 Wh | 11.99 |
| April | 161.56 kWh/m² | 3000 Wh | 18.57 |
| May | 135.47 kWh/m² | 3000 Wh | 22.15 |
| June | 157.44 kWh/m² | 3000 Wh | 19.05 |
| July | 149.74 kWh/m² | 3000 Wh | 20.03 |
| August | 178.82 kWh/m² | 3000 Wh | 16.78 |
| September | 172.36 kWh/m² | 3000 Wh | 17.41 |
| October | 170.63 kWh/m² | 2000 Wh | 11.72 |
| November | 161.02 kWh/m² | 2000 Wh | 12.42 |
| December | 164.17 kWh/m² | 2000 Wh | 12.18 |
- Month: The month of the year.
- Average daily insolation: Solar resource data obtained for the location from Weather and solar resource data sources.
- Average daily watt-hours required from load evaluation.
- Ratio = Average daily watt-hours required ÷ Average monthly insolation
Outputs
| Design daily insolation | = Average monthly insolation from month with the highest ratio ÷ 30 |
|---|
| Design daily watt-hours required | = Average daily watt-hours from month with the highest ratio |
|---|
