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electrical:solar:gentle_intro [2019/09/24 15:55] frater_secessus [daily power needs] |
electrical:solar:gentle_intro [2019/10/30 17:54] frater_secessus [limitations of solar] |
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A quick definition: the word [[electrical:nominal|nominal]] will crop up again and again in your reading, both here and elsewhere. In your head you can replace the word "nominal" with the phrase "so-called". //Nominal// refers to something's name, and the name for car electrical systems is "12v" even though it is very rarely literally 12.0 volts. | A quick definition: the word [[electrical:nominal|nominal]] will crop up again and again in your reading, both here and elsewhere. In your head you can replace the word "nominal" with the phrase "so-called". //Nominal// refers to something's name, and the name for car electrical systems is "12v" even though it is very rarely literally 12.0 volts. |
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| ===== how solar power works ===== |
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| Solar power uses [[electrical:solar:panels|solar panels]] to convert sunlight into electricity. This power is usually stored in a [[electrical:12v:deep_cycle_battery|deep-cycle "house" battery]], which is seperate from the vehicle's starter battery. Electricity from the panels is fed to the battery by a [[electrical:solar:charge_controller|solar charge controller]], which keeps the battery [[electrical:12v:charging|optimally charged]] and powers any [[electrical:12v:loads|loads]] (things that consume power). |
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Given these limitations why do we do spend so much time and money on solar? Because having power off-grid, however expensive and limited, can make a //huge// difference in quality of life. Solar is silent, works for decades, and is always working when the sun is shining.((portable solar only produces when deployed)) | Given these limitations why do we do spend so much time and money on solar? Because having power off-grid, however expensive and limited, can make a //huge// difference in quality of life. Solar is silent, works for decades, and is always working when the sun is shining.((portable solar only produces when deployed)) |
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===== how solar power works ===== | ===== first things first: daily power requirements ===== |
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| It's not fun but the first step in getting solar is to assess **daily power requirements**. It's like writing down all your monthly expenses when making a family budget. Unpleasant but necessary. |
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| Power requirements are assessed as **daily** because solar power feeds the batteries((and [[electrical:12v:loads|loads]])) only in daylight. Then at night the 'dweller pulls power back out of the batteries. So a **minimal solar configuration** will meet your daytime needs then get you through the night without running out of power. No one but you knows how much power you will need daytime and nighttime. |
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| ==== AC, DC, Amps, and Watts ==== |
| The basic idea is to tally up all the [[electrical:12v:loads|loads]] you want to run daily, the time in hours each will run, and the amount of power (Watts) each will consume while running. |
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| It is useful to calculate power use in Watts, because "watts are watts" no matter if it's a 12v load or a 120vac load.((inverter inefficiencies will be addressed later)) |
| * AC (household) devices will usually give consumption in watts on a label. |
| * DC devices may give watts, but more commonly show Amps on a label. From this we can derive watts: Amps from the label times voltage (12v) == watts |
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| First things first: Bill needed some idea of [[electrical:solar:sizing#your_daily_power_needs|how much power he actually needed each day]]. |
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| One way to figure it out is to [[electrical:solar:builds|see what configurations other people are running successfully in their own camper]] right now. The gamut runs from 100W to 1000W+, with 200W being the most common. |
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| The details of Bill's logic and math has been [[electrical:solar:daily-gentle|moved to its own page]], but for now we will stipulate he came up with a daily requirement of **91Ah** of usable battery capacity for each 24hr period. On average he will consume that much power each day, and will have to replace that amount((and a little bit more due to charging inefficiencies)) from the sun. |
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Solar power uses [[electrical:solar:panels|solar panels]] to convert sunlight into electricity. This power is usually stored in a [[electrical:12v:deep_cycle_battery|deep-cycle "house" battery]], which is seperate from the vehicle's starter battery. Electricity from the panels is fed to the battery by a [[electrical:solar:charge_controller|solar charge controller]], which keeps the battery [[electrical:12v:charging|optimally charged]] and powers any [[electrical:12v:loads|loads]] (things that consume power). | |
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===== the easy answer ===== | ===== the easy answer ===== |