| Both sides previous revision
Previous revision
Next revision
|
Previous revision
|
electrical:solar:gentle_intro [2023/08/23 21:23]
frater_secessus [Kits] |
electrical:solar:gentle_intro [2025/04/10 10:27] (current)
frater_secessus [What about flexible panels?] |
| > "...trying to take the comfort level you had in a house into your mobile life [is] tough to do for a boondocker." -- akrvbob((http://www.cheaprvliving.com/forums/Thread-Too-much-or-too-little-Solar?pid=116253#pid116253)) (Bob from Cheap RV Living) | > "...trying to take the comfort level you had in a house into your mobile life [is] tough to do for a boondocker." -- akrvbob((http://www.cheaprvliving.com/forums/Thread-Too-much-or-too-little-Solar?pid=116253#pid116253)) (Bob from Cheap RV Living) |
| |
| |
| > The fastest way to bring beginner expectations of solar in line with reality is to **assume you will run //nothing// off an inverter**. -- secessus | |
| |
| > Setting up solar that //works// is easy. Setting up solar that //works well// and //under challenging conditions// is much tougher. -- secessus | > Setting up solar that //works// is easy. Setting up solar that //works well// and //under challenging conditions// is much tougher. -- secessus |
| |
| * Making //some// power from solar is easy. | * Making //some// power from solar is easy. |
| * Making //sufficient power// from solar to cover your [[electrical:12v:dailypowerrequirements|daily power needs]] is much harder. | * Making //sufficient power// from solar alone to cover your [[electrical:12v:dailypowerrequirements|daily power needs]] is much harder. |
| * Making sufficient power from solar to cover your daily power needs //in all conditions, seasons, and locations// is so difficult and expensive that few attempt it; instead we [[electrical:12v:alt_and_solar|augment solar with other forms of charging]]. | * Making sufficient power from solar alone to cover your daily power needs //in all conditions, seasons, and locations// is so difficult and expensive that few attempt it; instead we [[electrical:12v:alt_and_solar|augment solar with other forms of charging]]. |
| * panels rarely make their rated output under real conditions | * panels rarely make their rated output under real conditions |
| | * solar makes power as needed. If there is no user or charging demand solar will twiddle its thumbs, waiting |
| * your //location// will have a huge effect on solar harvest | * your //location// will have a huge effect on solar harvest |
| | * //time of year// will have a huge effect on solar harvest |
| * shade on the panels will clobber output | * shade on the panels will clobber output |
| * panels still make some power under cloudy skies | * panels still make some power under cloudy skies |
| Getting //some// power from solar is easy. Getting //reliable// power from solar alone is challenging (and expensive) because solar harvest is greatly affected by [[electrical:solar:output|real-world conditions]]: latitude, season, shade, temperature, even battery voltage. It's bit harsh but you need to hear it early on: //you won't be getting 100w out of a 100w panel//, and //you won't be getting it for 8 hours a day//. | Getting //some// power from solar is easy. Getting //reliable// power from solar alone is challenging (and expensive) because solar harvest is greatly affected by [[electrical:solar:output|real-world conditions]]: latitude, season, shade, temperature, even battery voltage. It's bit harsh but you need to hear it early on: //you won't be getting 100w out of a 100w panel//, and //you won't be getting it for 8 hours a day//. |
| A crude rule of thumb might be meaningful solar harvest is possible only when the sun is throwing well-defined shadows on the ground. | A crude rule of thumb might be meaningful solar harvest is possible only when the sun is throwing well-defined shadows on the ground. |
| | |
| | Solar must not be shaded; not by weeds on the the ground or by other objects on the roof. The panel needs to be the tallest object in the general area. |
| |
| [[electrical:12v:alternator|Alternator charging]] helps address these shortcomings of solar charging (and //vice versa//) so it is [[electrical:12v:alt_and_solar|a common combination]]. | [[electrical:12v:alternator|Alternator charging]] helps address these shortcomings of solar charging (and //vice versa//) so it is [[electrical:12v:alt_and_solar|a common combination]]. |
| |
| * **best-effort** power - you take what you can get from the sun and [[electrical:solar:rationing|minimize power consumption]] to make do. No household appliances, at least not often. | * **best-effort** power - you take what you can get from the sun and [[electrical:solar:rationing|minimize power consumption]] to make do. No household appliances, at least not often. |
| * **reliable power** - you //need// power to keep insulin refrigerated, keep your external heart bypass machine running, etc. Prepare yourself for added complexity and/or cost because now you have to worry about harvest under poor solar conditions. | * **reliable power** - you //need// power to keep insulin refrigerated, keep working remotely, keep your external heart bypass machine running, whatever. Prepare yourself for added complexity and/or cost because now you have to worry about harvest under poor solar conditions. |
| * **massive solar** - You can still collect usable solar power under very poor conditions if you have [[electrical:solar:overpaneling|a huge amount of panel]]. This may require "maxxing out" your roofspace, tilting the panels, or deploying additional portable panels. Such configurations may be [[electrical:solar:builds#w6|1000w or more]]. One of the pleasant side effects of massive solar is that having //enough panel to meet needs in poor solar conditions// means //lots of bonus power in normal and good conditions//. You may be able to run [[electrical:solar:nonessential|non-essential loads]] without affecting your battery bank's [[electrical:depth_of_discharge|state of charge]]. | * **massive solar** - You can still collect usable solar power under very poor conditions if you have [[electrical:solar:overpaneling|a huge amount of panel]]. This may require "maxxing out" your roofspace, tilting the panels, or deploying additional portable panels. Such configurations may be [[electrical:solar:builds#w6|1000w or more]]. One of the pleasant side effects of massive solar is that having //enough panel to meet needs in poor solar conditions// means //lots of bonus power in normal and good conditions//. You may be able to run [[electrical:solar:nonessential|non-essential loads]] without affecting your battery bank's [[electrical:depth_of_discharge|state of charge]]. |
| * **solar + other forms of charging** - Solar can work much better when augmented by [[electrical:12v:alt_and_solar|additional sources of charging]]. It can work so well that less solar might be required and overall cost reduced. | * **solar + other forms of charging** - Solar can work much better when augmented by [[electrical:12v:alt_and_solar|additional sources of charging]]. It can work so well that less solar might be required and overall cost reduced. |
| Con | Con |
| |
| | * **they have to be deployed in order to work**. This would seem to be obvious, but setting out portable takes time and effort that humans do not always expend |
| | * portables can be tilted. |
| | * to seasonal optimal angles/azimuth. "Set it and forget it" |
| | * or turned to face the sun as it moves. An overlooked downside is that panels that are set up to follow the sun **must follow the sun** throughout the day. Human intervention required. |
| * panels made to be portable tend to be expensive per-watt. | * panels made to be portable tend to be expensive per-watt. |
| * **they have to be deployed in order to work** | |
| |
| On the last point: many people believe they will [[opinion:frater_secessus:beginner_mistakes#believing_they_will_set_out_portable_panels|set out their portables any time they are stopped]]; far fewer actually do it. | |
| | On the first point: many people believe they will [[opinion:frater_secessus:beginner_mistakes#believing_they_will_set_out_portable_panels|set out their portables any time they are stopped]]; far fewer actually do it. And even if they set them out they are sometimes placed in shade or facing away from the sun. We must pay attention; solar is unforgiving. |
| |
| |
| ===== What about flexible panels? ===== | ===== What about flexible panels? ===== |
| |
| Flex panels are very expensive by the watt. They are a great fit for people who need to mount on a curved surface (boat hull, teardrop trailer, etc) or store/lift a portable. | Good reasons to use flexible panels: |
| | |
| | * you need to mount panel on a gently curved surface (boat hull, teardrop trailer, etc) |
| | * you need lightest weight for portability |
| | * you are willing to tolerate higher costs and shorter life to get the above |
| | |
| | Bad reasons to use flexible panels: |
| | |
| | * because they are "cool" |
| | * because you saw an influencer use them on Insta/YT |
| | * because you want to walk on them (you can't) |
| |
| Otherwise framed panels are the standard for many good reasons. | Framed panels are the standard for many good reasons. If you must use flex, consider one of the non-crystalline types (CIGS, amorphous, thin-film, etc). It is not surprising that solid crystals a few inches wide don't like to flex. |
| ===== How much solar do I need? ==== | ===== How much solar do I need? ==== |
| |
| It is common to mount framed panels on a rack. This accomplishes a few things: | It is common to mount framed panels on a rack. This accomplishes a few things: |
| |
| | |
| | [[https://amzn.to/45VXHEC|{{ https://m.media-amazon.com/images/I/51qQl5nwz6L._AC_UY218_.jpg?75}}]] |
| * allows the panels to always be deployed | * allows the panels to always be deployed |
| * where they won't fall over, walk off, or be urinated on by loose dogs | * where they won't fall over, walk off, or be urinated on by loose dogs |
| * allows underside cooling to minimize [[electrical:solar:output#panel_temperature|heat-related losses]] and re-radiation from superheated panels into the van interior | * allows underside cooling to minimize [[electrical:solar:output#panel_temperature|heat-related losses]] and re-radiation from superheated panels into the van interior |
| | * to keep from drilling extra holes in the roof. Some vans have rack mountpoints built in and don't require any holes for mounting the rack. |
| | * at least one hole will be required for solar panel wiring entry; this is typically routed through [[https://amzn.to/45VXHEC|a weatherproof cable gland]]. |
| | * allow changes later; drill new holes in the rack instead of in the roof |
| |
| Note: avoid racks with "ladder retainers" or other vertical elements. [[electrical:solar:output#shade|Partial shading]] is brutal on solar harvest, and //carrying around your own shade// is an "unforced error". If you have inherited a rack with uprights consider cutting them off. | Note: avoid racks with "ladder retainers" or other vertical elements. [[electrical:solar:output#shade|Partial shading]] is brutal on solar harvest, and //carrying around your own shade// is an "unforced error". If you have inherited a rack with uprights consider cutting them off. If you can't cut them off mount the panels as far away from the uprights as possible. If you have a basket the panels need to be on top of (or flush with) the basket instead down inside it. |
| |
| |
