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 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: |
| + | |||
| + | *Design insolation | ||
| + | *Average 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="pvwatts"> PVWatts Calculator https://pvwatts.nrel.gov/pvwatts.php</ref> The load evaluation shows that loads will be used more frequently during the rainy season, which is common. | '''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="pvwatts"> PVWatts Calculator https://pvwatts.nrel.gov/pvwatts.php</ref> The load evaluation shows that loads will be used more frequently during the rainy season, which is common. | ||
| − | *July (highlighted in red) has the worst ratio of solar resource relative to energy requirement throughout the year. The | + | *July (highlighted in red) has the worst ratio of solar resource relative to energy requirement throughout the year. The average insolation value (3.39 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 13: | Line 16: | ||
|January | |January | ||
|6.06 kWh/m² | |6.06 kWh/m² | ||
| − | | | + | |2000Wh |
| − | | | + | |330 |
|- | |- | ||
|February | |February | ||
|6.32 kWh/m² | |6.32 kWh/m² | ||
| − | | | + | |2000Wh |
| − | | | + | |316 |
|- | |- | ||
|March | |March | ||
|6.49 kWh/m² | |6.49 kWh/m² | ||
| − | | | + | |2000Wh |
| − | | | + | |308 |
|- | |- | ||
|April | |April | ||
|6.42 kWh/m² | |6.42 kWh/m² | ||
| − | | | + | |2000Wh |
| − | | | + | |311 |
|- | |- | ||
|May | |May | ||
|5.00 kWh/m² | |5.00 kWh/m² | ||
| − | | | + | |2000Wh |
| − | | | + | |600 |
|- | |- | ||
|June | |June | ||
|3.75 kWh/m² | |3.75 kWh/m² | ||
| − | | | + | |3000Wh |
| − | | | + | |800 |
|- style="background-color:#F08080;" | |- style="background-color:#F08080;" | ||
|July | |July | ||
|3.39 kWh/m² | |3.39 kWh/m² | ||
| − | | | + | |3000Wh |
| − | | | + | |885 |
|- | |- | ||
|August | |August | ||
|3.69 kWh/m² | |3.69 kWh/m² | ||
| − | | | + | |3000Wh |
| − | | | + | |813 |
|- | |- | ||
|September | |September | ||
|4.21 kWh/m² | |4.21 kWh/m² | ||
| − | | | + | |3000Wh |
| − | | | + | |713 |
|- | |- | ||
|October | |October | ||
|5.17 kWh/m² | |5.17 kWh/m² | ||
| − | | | + | |3000Wh |
| − | | | + | |580 |
|- | |- | ||
|November | |November | ||
|5.27 kWh/m² | |5.27 kWh/m² | ||
| − | | | + | |2000Wh |
| − | | | + | |380 |
|- | |- | ||
|December | |December | ||
|5.60 kWh/m² | |5.60 kWh/m² | ||
| − | | | + | |2000Wh |
| − | | | + | |357 |
|} | |} | ||
*'''Month:''' The month of the year. | *'''Month:''' The month of the year. | ||
| Line 75: | Line 78: | ||
*'''[[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 daily insolation | ||
| + | |||
==Notes/references== | ==Notes/references== | ||
<references/> | <references/> | ||
Revision as of 12:20, 20 November 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 insolation:
- Design insolation
- Average 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.
- July (highlighted in red) has the worst ratio of solar resource relative to energy requirement throughout the year. The average insolation value (3.39 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 | 6.06 kWh/m² | 2000Wh | 330 |
| February | 6.32 kWh/m² | 2000Wh | 316 |
| March | 6.49 kWh/m² | 2000Wh | 308 |
| April | 6.42 kWh/m² | 2000Wh | 311 |
| May | 5.00 kWh/m² | 2000Wh | 600 |
| June | 3.75 kWh/m² | 3000Wh | 800 |
| July | 3.39 kWh/m² | 3000Wh | 885 |
| August | 3.69 kWh/m² | 3000Wh | 813 |
| September | 4.21 kWh/m² | 3000Wh | 713 |
| October | 5.17 kWh/m² | 3000Wh | 580 |
| November | 5.27 kWh/m² | 2000Wh | 380 |
| December | 5.60 kWh/m² | 2000Wh | 357 |
- 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 daily insolation
Notes/references
- ↑ PVWatts Calculator https://pvwatts.nrel.gov/pvwatts.php
