Difference between revisions of "Load and solar resource comparison"
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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 [[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. | ||
| − | Example | + | '''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. |
{| class="wikitable" border=1 | {| class="wikitable" border=1 | ||
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|3.00kWh | |3.00kWh | ||
|.800 | |.800 | ||
| − | |- | + | |- style="background-color:#FF4500; |
|July | |July | ||
|3.39 kWh/m² | |3.39 kWh/m² | ||
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|.357 | |.357 | ||
|} | |} | ||
| + | ==Notes/references== | ||
| + | <references/> | ||
Revision as of 07:15, 12 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.
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.
| Month | Average daily insolation | Total average monthly Wh requirement | Ratio |
|---|---|---|---|
| January | 6.06 kWh/m² | 2.00kWh | .330 |
| February | 6.32 kWh/m² | 2.00kWh | .316 |
| March | 6.49 kWh/m² | 2.00kWh | .308 |
| April | 6.42 kWh/m² | 2.00kWh | .311 |
| May | 5.00 kWh/m² | 3.00kWh | .600 |
| June | 3.75 kWh/m² | 3.00kWh | .800 |
| July | 3.39 kWh/m² | 3.00kWh | .885 |
| August | 3.69 kWh/m² | 3.00kWh | .813 |
| September | 4.21 kWh/m² | 3.00kWh | .713 |
| October | 5.17 kWh/m² | 3.00kWh | .580 |
| November | 5.27 kWh/m² | 2.00kWh | .380 |
| December | 5.60 kWh/m² | 2.00kWh | .357 |
Notes/references
- ↑ PVWatts Calculator https://pvwatts.nrel.gov/pvwatts.php
