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electrical:solar [2017/05/28 18:13] frater_secessus [sizing a solar installation] |
electrical:solar [2020/02/16 11:14] frater_secessus [weather-related issues] |
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+ | **Words of Wisdom:** I'm not sure people always grasp the concept of " | ||
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====== Solar power ====== | ====== Solar power ====== | ||
- | Solar (photovoltaic or PV) power is an excellent fit for ' | + | [Note: |
+ | |||
+ | Solar (photovoltaic or PV) power is an excellent fit for ' | ||
Broadly speaking, **solar power systems consist of** [[electrical: | Broadly speaking, **solar power systems consist of** [[electrical: | ||
- | Under normal use solar setups charge during the daytime and discharge at night; the lowest [[electrical: | + | Under normal use solar setups charge |
- | The most difficult part of a solar power system (other than paying for it!) is [[electrical: | + | The most difficult part of a solar power system (other than [[electrical: |
- | ===== things that affect solar power ===== | + | |
- | * Insolation (Intensity of sunlight) | ||
- | * hours of sun each day | ||
- | * clouds - panels make more power on sunny days and less on cloudy days, due to increased current (voltage relatively unchanged) | ||
- | * temperature - panels make more power when cold, due to increased voltage (current relatively unchanged) | ||
- | * physical obstruction / shade - | ||
- | * physical obstruction / covering - | ||
+ | ===== do you really need solar? ===== | ||
+ | Maybe not. If any of these conditions are met you probably don't need solar: | ||
- | ===== sizing | + | * you stay in campgrounds or other places with access to [[electrical: |
+ | * you have a [[electrical: | ||
- | ==== amp-hours needed ==== | ||
- | There are calculators online that will tell you how much panel and battery you need. That is the easy part. | ||
- | The **hardest part is figuring out what your daily power needs really are**. | ||
- | If you are going to be using both 12vdc and 110vac (through an inverter) it may be easier to do the calculation in watts, then convert to Amps DC by dividing by 12. Otherwise an [[https:// | ||
- | Note: remember you can't use all the capacity of a battery; | + | ===== practical considerations ===== |
+ | * [[electrical: | ||
+ | * panels are coming down in price but are $$$ to ship. Where will you get them? | ||
+ | * wiring from the panels will have to enter the camper body somewhere, and the entry will have to be waterproof | ||
+ | * lead acid batteries (flooded, sealed, AGM, etc) are extremely heavy and bulky. | ||
+ | * wiring from power sources will need to be fused or fitted with circuit breakers | ||
+ | * how will you ensure your batteries don't run your batteries too low and damage them? | ||
+ | |||
+ | ===== scheduling your use of solar power ===== | ||
+ | |||
+ | //When// you use power from your system can be as important as //how much// power you use. | ||
+ | |||
+ | There are times (bulk, early absorption) when the system is struggling to charge the lead-chemistry bank; loads should be minimized during these periods. | ||
+ | |||
+ | At other times like late absorption and float the system will have [[electrical: | ||
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+ | |||
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+ | |||
+ | ===== things that affect solar power ===== | ||
+ | |||
+ | * Insolation (Intensity of sunlight) | ||
+ | * **strongest** when there is least atmosphere between the sun and panels: | ||
+ | * **weakest** when there is the most atmosphere between sun and panels: | ||
+ | * hours of sun each day - more in southern latitudes and in summer; fewer in northern latitudes and in winter | ||
+ | * clouds - panels make more power on sunny days and less on cloudy days, due to increased current (voltage relatively unchanged). | ||
+ | * temperature - panels make more power when cold, due to increased voltage (current relatively unchanged) | ||
+ | * physical obstruction / shade - as when in forested areas | ||
+ | * physical obstruction / covering - as when covered in dust or snow | ||
- | === number of days === | ||
- | |||
- | Build in capacity for days when there is little solar energy available: | ||
+ | ===== how much solar? ===== | ||
+ | Solar sizing has been moved to [[electrical: | ||
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===== weather-related issues ===== | ===== weather-related issues ===== | ||
+ | Weather and [[electrical: | ||
==== cloudy weather ==== | ==== cloudy weather ==== | ||
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* when the **sun is near the edge of a cloud** you can get spikes in current, called Edge of Cloud Effect (ECE). | * when the **sun is near the edge of a cloud** you can get spikes in current, called Edge of Cloud Effect (ECE). | ||
- | Rainy weather causes a drop in current due to the cloud cover effect. | + | Rainy weather causes a drop in current due to the cloud cover effect. An upside is it can wash dust off panels. |
Dusty or snowy weather can cause a loss of output due to physical presence on the panels. | Dusty or snowy weather can cause a loss of output due to physical presence on the panels. |