| Both sides previous revision
Previous revision
Next revision
|
Previous revision
Next revision
Both sides next revision
|
electrical:solar:gentle_intro [2019/09/24 16:31]
frater_secessus [daily power needs] |
electrical:solar:gentle_intro [2019/10/30 17:58]
frater_secessus [panels] |
| |
| 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. |
| | |
| | |
| | ===== how solar power works ===== |
| | |
| | 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). |
| |
| |
| 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. | 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. |
| |
| ===== how solar power works ===== | |
| |
| 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). | |
| |
| ===== the easy answer ===== | ===== the easy answer ===== |
| Solar setups require a //battery bank// of some kind, even during the daytime.((this is to help the controller stay stable)) In simple installs the bank is one or two batteries.((not including your vehicle's starter battery)) The battery also stores excess power. At night or any other time your demand is higher than your solar is pumping out, you will be pulling power from the battery. | Solar setups require a //battery bank// of some kind, even during the daytime.((this is to help the controller stay stable)) In simple installs the bank is one or two batteries.((not including your vehicle's starter battery)) The battery also stores excess power. At night or any other time your demand is higher than your solar is pumping out, you will be pulling power from the battery. |
| |
| For reasons related to the chemistry of [[electrical:12v:deep_cycle_battery|deep cycle batteries]], it takes twice the amount of battery bank Ah rating to deliver the daily Ah requirement: | For reasons related to the chemistry of lead-acid [[electrical:12v:deep_cycle_battery|deep cycle batteries]], it takes twice the amount of battery bank Ah rating to deliver the daily Ah requirement: |
| |
| | **total**| 91| | | **total**| 91| |
| * staying at a RV park with hookups on bad days | * staying at a RV park with hookups on bad days |
| * buying a [[electrical:generator|generator]] | * buying a [[electrical:generator|generator]] |
| * investing in lithium or other exotic batteries | * investing in [[electrical:12v:deep_cycle_battery#lithium_chemistries|lithium]] or other exotic batteries |
| * [[electrical:12v:alt_and_solar|adding alternator charging]] to the mix | * [[electrical:12v:alt_and_solar|adding alternator charging]] to the mix |
| |
| A common rule of thumb for solar-only charging is that one needs one watt of solar for every Ah of rated battery capacity. 2:1 is recommended for winter or other challeging conditions, and 3x is even better for off-grid folks.((1:1 is usually sufficient if solar charging is [[electrical:12v:alt_and_solar|augmented with alternator or other sources]]. 2:1 might still be required in areas lihe the Pacific Northwest.)) | A common rule of thumb for solar-only charging is that one needs one watt of solar for every Ah of rated battery capacity. 2:1 is recommended for winter or other challeging conditions, and 3x is even better for off-grid folks.((1:1 is usually sufficient if solar charging is [[electrical:12v:alt_and_solar|augmented with alternator or other sources]]. 2:1 might still be required in areas lihe the Pacific Northwest.)) |
| |
| So about 200w of solar is a good fit for Bill's 200Ah golf cart bank if he stays in a sunny area like the desert southwest. | So about 200w of solar is a good fit for Bill's 200Ah golf cart bank if he stays in a sunny area like the desert southwest. In the Pacific NW he'd be better off with something like 600w. |
| |
| | **Ratio W:Ah**| **Panel watts**| | | **Ratio W:Ah**| **Panel watts**| |
