Difference between revisions of "Load and solar resource comparison"
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*Design insolation | *Design insolation | ||
| − | *Design daily | + | *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="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. | ||
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*'''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 | + | *'''[[Load evaluation#Average daily watt-hours required|Average daily watt-hours required]]''' from load evaluation. |
| − | *'''Ratio =''' Average daily | + | *'''Ratio =''' Average daily watt-hours required ÷ Average daily insolation |
==Notes/references== | ==Notes/references== | ||
<references/> | <references/> | ||
Revision as of 14:11, 16 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 insolation:
- Design 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.
- 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 | 2000 Wh | 330 |
| February | 6.32 kWh/m² | 2000 Wh | 316 |
| March | 6.49 kWh/m² | 2000 Wh | 308 |
| April | 6.42 kWh/m² | 2000 Wh | 311 |
| May | 5.00 kWh/m² | 2000 Wh | 600 |
| June | 3.75 kWh/m² | 3000 Wh | 800 |
| July | 3.39 kWh/m² | 3000 Wh | 885 |
| August | 3.69 kWh/m² | 3000 Wh | 813 |
| September | 4.21 kWh/m² | 3000 Wh | 713 |
| October | 5.17 kWh/m² | 3000 Wh | 580 |
| November | 5.27 kWh/m² | 2000 Wh | 380 |
| December | 5.60 kWh/m² | 2000 Wh | 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
