| Both sides previous revision
Previous revision
Next revision
|
Previous revision
|
electrical:solar:gentle_intro [2018/10/17 11:46]
frater_secessus [charge controller] |
electrical:solar:gentle_intro [2023/11/07 11:19] (current)
frater_secessus [TLDR] |
| > A good solar system is one that meets //your// needs. -- jimindenver((paraphrased)) | > A good solar system is one that meets //your// needs. -- jimindenver((paraphrased)) |
| |
| > The fastest way to bring beginner expectations of solar in line with reality is to **assume you will run //nothing// off an inverter**. -- secessus | > "...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) |
| | |
| | |
| | > Setting up solar that //works// is easy. Setting up solar that //works well// and //under challenging conditions// is much tougher. -- secessus |
| |
| |
| ====== A gentle introduction to solar ====== | ====== A gentle introduction to solar ====== |
| |
| This page aims to provide beginners with a basic overview of solar power for nomads. There are oversimplifications and concepts skipped for clarity. If you would like a refresher on basic electronics, see [[https://www.youtube.com/watch?v=eTvXx9tBkuU|the AltE Intro to Electronics for solar]] video. | This page is a basic overview of solar power for beginner nomads. There are oversimplifications and concepts skipped for clarity; click on the links for more information on a topic. |
| |
| A quick definition: the word //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". The most common use is "nominal 12v", referring to the common automotive 12v system. The term is used for historical reasons and is almost never literally 12.00 volts. In fact, a lead-acid battery is [[electrical:depth_of_discharge|over-discharged]] at 12.0v! | |
| |
| | If you would like a refresher on basic electronics, see [[https://www.youtube.com/watch?v=eTvXx9tBkuU|the AltE Intro to Electronics for solar]] video. |
| |
| ===== limitations of solar ===== | |
| |
| Solar is not a magic bullet; it is a compromise like anything else. | ===== TLDR ===== |
| |
| **Solar is expensive for the amount of power you get out of it.** It can cost several thousand dollars to get the same amount of reliable power one might might get from a residential (or campsite) outlet with a $20 extension cord. | * 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 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 |
| | * 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 |
| | * panels still make some power under cloudy skies |
| |
| **[[electrical:solar:rationing|Minimizing power consumption]] is key** to happiness with a simple, affordable solar setup. It requires a change in mindset for most folks. Electrical power becomes a precious resource to be carefully consumed. The **path to frustration** (or at least considerable expense) involves [[hvac:solar|heating or cooling with electricity]] or trying to run household appliances in a van. | [[opinion:frater_secessus:pareto|about this summary]] |
| | ===== Benefits of solar ===== |
| |
| > "...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)) | Solar power is silent, works for decades, and is always working when the sun is shining.((portable solar only produces when deployed)) It can [[electrical:12v:charging|recharge your batteries]] and [[electrical:solar:offthepanel|run your loads]]. |
| |
| The amount of power a solar configuration outputs is [[electrical:solar:output|greatly affected by things like latitude, season, shade, temperature, and even battery voltage]]. | Solar is nearly mandatory for charging lead-chemistry batteries off-grid, since those require of [[electrical:12v:charging#absorption_stage|many hours of charging]].((Solar is [[electrical:12v:mandatory_solar|not mandatory]] with lithium or chemistries that aren't harmed by [[electrical:12v:psoc|partial state of charge.]])) Failure to charge lead batteries((AGM is lead!)) fully and regularly leads to [[electrical:batterycide|battery murder]]. Solar helps prevent battery murder and the resulting $$ battery replacements. |
| |
| Since it looks like magic, beginners tend to worry about [[electrical:solar:status#is_my_solar_working|whether or not their system is working]]. It usually is. | For people who can [[electrical:solar:rationing|control their power consumption]], even a small amount of solar can greatly extend time off-grid and can make a //huge// difference in quality of life. |
| |
| |
| 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)) | |
| |
| ===== 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). | ===== Limitations of solar ===== |
| |
| ===== the easy answer ===== | Solar is not a magic bullet; it is a compromise like anything else. **Solar has very high startup costs for the amount of power you get out of it.** It could cost several thousand dollars to get the same amount of reliable power one might might get from [[electrical:shore_power|a residential (or campsite) outlet]] with a $20 extension cord. Over time, though, the power is "free". |
| |
| Kits are available that handle the basics at a reasonable price. [[electrical:solar:builds#w1|200W of solar is the most common]] campervan setup, and is sufficient for most campers that do not run [[electrical:inverter|inverter]] (residential appliance) loads.((Yes, you //can// run inverter loads. The problem is not with the inverter; it is with users who do not realize how much power residential appliances consume. Planning to have no inverter will build in realistic expectations from the beginning. -- secessus)) | 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. |
| |
| Are kits the penny-pinching cheapest, or the highest tech, or the most tacticool military/marine grade option? No. But the average user doesn't need those attributes. And once users get comfortable with how their system works it can often be tweaked for better operation by adjusting [[electrical:solar:charge_controller_setpoints|controller setpoints]]. | 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. |
| |
| For now, let's consider some common kit-based installations. The terms used will be discussed later in the page in case you don't recognize some of them. | [[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]]. |
| | ===== How solar power works ===== |
| |
| * [[http://amzn.to/2ztSSoO|200W kit]] + a [[electrical:12v:deep_cycle_battery#chain_store_batteries|wally world learner battery]] is about $450 at late 2017 prices. This is about $1.75 per solar watt produced((actually going out of the controller into the battery)) and would cost **~$750 over 5 years**, including expected battery replacement. | Solar power uses [[electrical:solar:panels|solar panels]] to convert sunlight into electricity. This electricity goes into [[electrical:solar:charge_controller|solar charge controller]], which keeps the battery [[electrical:12v:charging|optimally charged]]((or attempts to!)) and powers any [[electrical:12v:loads|loads]] (things that consume power). The controller extracts the precise amount of power your batteries+loads demand and no more: in effect the controller is //pulling// rather than the panels //pushing//. |
| * 200W kit + 2 x [[electrical:12v:deep_cycle_battery#v_golf_cart_batteries|6v golf cart battery]] bank is about $550 at late 2017 prices. This is about $1.75 per solar watt, and would cost **~$550 over 5 years**. Flooded lead acid golf cart batteries are the most tolerant of beginner mistakes, and will take the most abuse. | |
| * [[http://amzn.to/2zrtTR5|200W kit w/MPPT controller]] + 2 x 6v golf cart batteries is about $675 at late 2017 prices. This is about $2.37 per solar watt, and would cost $675 over 5 years.((using a locally sourced 24v panel with the MPPT controller would bring the cost down to $1.25/solar watt)) | |
| * 200W kit w/MPPT controller + [[electrical:12v:deep_cycle_battery#agm|AGM battery]] bank is about $875 at late 2017 prices. This is about $2.37 per solar watt, and would cost **$965 over 5 years**~. Note: AGM batteries are not particularly well suited for solar-only charging.((http://www.cheaprvliving.com/forums/Thread-How-much-of-an-issue-is-battery-off-gassing?pid=144704#pid144704)) | |
| |
| 200W is not a magic number, but it is the most common size of solar install for vandwellers and [[camping:dispersed|boondockers]]. It is probably more than what's needed for the basics and has enough power to add in a [[food:refrigeration#compressor_refrigeration|12v compressor refrigerator]] if desired.((assuming good conditions like the desert southwest)) | Overall it is arranged like this: |
| |
| Going beyond the basics, handling the basics more frugally, or running non-trivial loads off an inverter will require more research, planning and patience. Read on, and follow links in the text to drill down to deeper explanations. Beware that some of the links are technical. | |
| |
| | panels -> controller -> battery bank -> loads |
| |
| | Excess power((that which of what you are using for loads)) is stored up in a [[electrical:12v:deep_cycle_battery|deep-cycle "house" battery]] during daylight((as long as the battery bank can accept it)) and the power is pulled back out at night. The house battery is electrically separate from the vehicle's starter battery.((unless combined using [[electrical:12v:alternator#isolators|an isolator]], or running a [[electrical:solar:shallow_cycling|single-battery setup]])) In broad terms... |
| |
| | > "Think of the batteries as a bucket of electricity. It's possible to pour water from [[electrical:12v:multipoint_charging|multiple sources into a bucket at the same time]], and also to do that while water is leaking out of the bucket." -- MarkSF((https://www.cruisersforum.com/forums/f14/multiple-sources-of-dc-voltage-being-fed-to-battery-bank-246008.html#post3335865)) |
| |
| | [[electrical:12v:charging|Battery charging]] is a topic unto itself, and improper charging can [[electrical:batterycide|kill batteries prematurely]]. |
| |
| | Since it looks like magic, beginners tend to worry about [[electrical:solar:status#is_my_solar_working|whether or not their system is working]]. The solar setup is usually working as intended, and over time you will begin to learn how your system behaves. In the beginning you may watch it constantly(("solar tv")) then eventually need to check "the gauges" less and less often. At some point you will be able to predict what the system is doing before looking. |
| |
| ===== a typical DIY setup ===== | ===== Your approach to solar ===== |
| |
| BLM Bill across the wash over there built a system he successfully uses to run LED lights and [[hvac:roof_vent|roof vent]], charge a phone/[[electrical:12v:laptop|laptop]], and run [[food:refrigeration|a 12v refrigerator]]. It is made up of the following components: | Since reliable power by solar alone is tough, there are a few approaches to consider: |
| |
| * Two 100w [[electrical:solar:panels|solar panels]] | * **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. |
| * Two 6v golf cart [[electrical:12v:deep_cycle_battery|deep cycle batteries]] in [[electrical:12v:parallel_serial|series]] to make a 12v bank | * **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. |
| * A 20A solar [[electrical:solar:charge_controller|charge controller]] | * **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]]. |
| * a [[electrical:12v:ports|12v power port]] with [[electrical:USB|USB outlets]] | * **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. |
| |
| You've never seen him run out of power. He isn't //wasteful// with power but is not [[electrical:solar:frugal|obsessed with conserving every watt]], either. He has a functional, comfortable system suited to his needs. | |
| |
| So how did he pick those components? How did he know they would work? Where did he start? [[electrical:solar:builds|What are other people doing?]] How the heck does anyone untangle this stuff?((by mastering small sections at a time!)) | |
| |
| | ===== What about portable panels? ===== |
| |
| ==== daily power needs ==== | Pro |
| |
| | * can be set in sun while vehicle is in shade |
| | * can add more power when mounted panels are insufficient |
| | * can be tilted easily |
| |
| First things first: Bill needed some idea of [[electrical:solar:sizing#your_daily_power_needs|how much power he actually needed each day]]. | Con |
| |
| 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. | * 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. |
| |
| 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**. 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. | |
| ==== 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. | ===== What about flexible panels? ===== |
| |
| 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: | 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. |
| |
| | **total**| 91| | Otherwise framed panels are the standard for many good reasons. |
| | | | | ===== How much solar do I need? ==== |
| | Minimum battery bank((except lithium))| 182| | |
| |
| | This question usually means "how much //power// do I need?" and involves **making power**((solar, [[electrical:generator|generator]], [[electrical:12v:alternator|isolator]], [[electrical:shore_power|shore power]], etc)), **storing power**(([[electrical:12v:deep_cycle_battery|deep cycle battery]] bank)), and **using power**(([[electrical:12v:loads|12v loads]], [[electrical:inverter|inverter]] loads)). Unfortunately, you are the only person who knows how much power you will need, and even //you// may not know yet. :-) Strangers on the internet cannot tell you how much power you need anymore than they can tell you who to date or how many kids to have. |
| |
| and that's just to get through a 24hr period **with good sun**. If you want to get through a day (or more) of terrible solar yield (rain, snow, fog) it requires even more battery capacity (//reserve//), money, and cargo capacity. These numbers are both very rough but will illustrate the pattern: | It's not fun but the first step in getting solar is to [[electrical:12v:intro#how_much_power_do_i_need|assess your daily power requirements]]. Until they sit down to do the math first-timers often have [[opinion:frater_secessus:beginner_mistakes#electrical_power|radically unrealistic ideas about power]] in the campervan. You probably won't be able to run a hair dryer, electric space heater, [[hvac:solar_ac|air conditioner]], instant pot, or other high-wattage loads from solar. |
| |
| | | **Rated Ah**| **cost (flooded)**| **cost (AGM)**| **weight in lbs**| | **Note:** you can get a ballpark idea before crunching your own numbers by [[electrical:solar:builds|reviewing some existing solar installs]]. |
| | **Minimum battery bank((except lithium)) | |
| 0 days of reserve**| 182| $182.00| $364.00| 91| | |
| | | | | | | | |
| | **1 day of reserve**| 364| $364.00| $728.00| 182| | |
| | **2 days of reserve**| 546| $546.00| $1,092.00| 273| | |
| | **3 days of reserve**| 728| $728.00| $1,456.00| 364| | |
| |
| |
| Don't panic! You don't need to spend thousands of dollars. In practice, many vandwellers do not design for extra days of reserve, planning on just not having power (or not much power) on rainy days. And there are other ways to compensate for rainy days: | |
| |
| * [[electrical:solar:frugal|voluntarily using less power]]. This approach has the added benefit of costing nothing but does require some study and discipline | ==== Why daily? ==== |
| * [[electrical:solar:overpaneling|overpaneling]] to harvest usable power even in challenging conditions like rain and overcast skies | |
| * staying at a RV park with hookups on bad days | |
| * buying a [[electrical:generator|generator]] | |
| * investing in lithium or other exotic batteries | |
| * [[electrical:12v:alt_and_solar|adding alternator charging]] to the mix | |
| |
| | Power requirements are calculated **daily** because the solar feeds the batteries((and [[electrical:12v:loads|loads]])) only in daylight. Then at night the system pulls power back out of the batteries. This is natural rhythm of a solar-powered system and the reason why deep-cycle batteries are used. |
| |
| | A **minimal solar configuration** will |
| |
| The most beginner tolerant and value-for-money battery bank is two **6v deep cycle "golf cart" batteries** [[electrical:12v:parallel_serial|wired in series]] to make 12v. This will provide 200+ Ah (amp-hours) of rated capacity.((100+ Ah of usable capacity)) This bank gives Bill one normal day's use and and about a half/day of of reserve (ie, a day with no charging). A set of golf carts like this will be sufficient for most needs and does well with 200-500W of solar panel. Deep cycle batteries should be [[electrical:depth_of_discharge|discharged no lower than 50%]] to avoid damaging them. This is about 12.2v. A [[electrical:12v:lvd|Low Voltage Disconnect]] can help prevent deeper, damaging discharge. | * meet your daytime needs |
| | * then get you through the night without running out of power or overdischarging the battery |
| | * meet your needs again the next day **while also recharging the battery** |
| |
| Yes, they should be vented. No, not everyone does. | People who are off-grid for longer stretches will also have to think about [[electrical:solar:sizing#your_reserve_needs|reserve power]]. It's not so much an issue for recreational campers who will likely camp only in good weather, and can return home to charge in any case. |
| |
| Sternwake says: | |
| |
| > "I don't think any battery is going to out cycle a 6v flooded golf cart battery. These are simply the most tolerant of the type of usage typically seen in this lifestyle."((http://www.cheaprvliving.com/forums/Thread-Intro-Solar-Questions?pid=192079#pid192079)) | |
| |
| Because beginners commonly [[electrical:batterycide|murder their first battery bank]], a common beginner's battery is a [[electrical:12v:deep_cycle_battery#chain_store_batteries|Walmart "deep cycle" / marine battery]], preferably one with removable cell caps for adding distilled water as needed. Often called a "learner battery", they do not have long lives or much capacity but are widely available nationwide and often have pro-rated warranties. A walmart battery will usually have half the capacity of actual deep cycles, so Bill would get one nights's power with no reserve for rainy days. | ===== Should I build or buy solar? ===== |
| |
| Also common are **AGM** batteries, a sealed type. They do not have to be vented under normal conditions and have very high charge/discharge rates. On the downside they cost 2x as much, require vigorous charging one generally cannot get with [[electrical:12v:alt_and_solar|solar charging alone]], cannot be charged to as high a voltage, and have less capacity.((http://www.cheaprvliving.com/forums/Thread-Considering-battery-s-for-the-future?pid=347419#pid347419)) | In order from traditional to more recent approaches |
| |
| About these Sternwake says: | ==== DIY ==== |
| |
| > "While AGMs are considered a no maintenance battery if they were a person... they would be considered high maintenance... and only with a surplus of everything they want could they be kept happy."((http://www.cheaprvliving.com/forums/Thread-Intro-Solar-Questions?pid=192079#pid192079)) | DIY (do it yourself) means selecting component components individually ([[electrical:solar:panels|panels]], [[electrical:solar:charge_controller|solar charge controllers]], [[electrical:12v:deep_cycle_battery|batteries]], [[electrical:inverter|inverters]], [[electrical:12v:alternator|isolators]], etc) and installing them yourself. |
| |
| A single 12v AGM would get Bill through one night; two can be paralleled to double capacity to nearly match the capacity of the golf cart batteries. | **Pro:** Typically lowest cost. Components precisely meet your specific needs. You know where everything is, what it does, and how to replace it if it fails. |
| |
| ==== panels ==== | **Con:** Time-consuming. You have to learn enough to pick components and install them. |
| |
| 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. | |
| |
| | **Ratio W:Ah**| **Panel watts**| | ==== Kits ==== |
| | **1:1 solar**| 182| | |
| | **2:1 solar**| 364| | |
| | **3:1 solar**| 546| | |
| |
| | Kits are usually **solar panels, charge controllers**, and perhaps **related hardware** sold in one (hopefully) well-matched package. You will typically need to add your own battery, inverter, etc, as needed. |
| |
| | **Pro:** some of the product selection is outsourced for you |
| |
| Considering the solar panels themselves, there are framed panels ([[electrical:solar:panels#monocrystalline|mono]], [[electrical:solar:panels#monocrystalline|poly]]), and semi-flexible ([[electrical:solar:panels#thin_film|amorphous]]) panels. Buy whatever: | **Con:** likely could get better quality and better-matched components for less money with DIY. Packages are often put together by marketing teams instead of engineering or support teams and sometimes [[https://mouse.mousetrap.net/blog/2019/11/13/pwm-loves-poly/|the combinations don't work as well as they could]]. |
| |
| - fits on your roof | |
| - is the cheapest per watt | |
| |
| This usually means framed panels, as flex panels are usually 2+ times more expensive per watt and are less rugged. Flex panels do have legitimate uses but they are specialty panels and are not recommended as a default panel for most builds. | ==== Portable power stations ==== |
| |
| Arrays of two 100W panels are popular because 100w panels can be shipped individually by UPS/FedEx. Larger panels may require $$$ truck shipping; try to buy those locally if possible to avoid shipping fees. | Often called [[lifestyle:faq_solar_generator|solar generators]], these devices are neither //solar// nor //generators//. They are all-in-one systems packaging a battery, an inverter, DC outputs, and allowing various forms of charging.((including from solar)) |
| |
| 100W panels are usually nominal 12v; [[electrical:solar:panels#panel_voltage|there are also 20v and 24v panels]] one can source from the solar grid-tied market. The higher voltages panels require a MPPT controller (see below) but tend to be cheaper per watt. | **Pro:** all of the product selection is outsourced for you. Portable and generally attractive package. |
| |
| The two main types of panel in 2018 are **monocrystalline** (//mono//) and **polycrystalline** (//poly//). The technical details are unimportant but you will see panels described as mono or poly when you are researching. Due to relatively small differences in their voltages, **poly panels are slightly better suited to PWM charge controllers**, and **mono panels((and "high voltage" 20v/24v panels)) are slightly better suited to MPPT controllers**. These controllers are discussed next. | **Con:** very expensive for what you get, and what you get is someone else's idea of what you should want. Generally not repairable by the end user. People with heavier power needs may find SGs challenging to intergrate into camper wiring. |
| ==== charge controller ==== | |
| |
| The charge controller stands between the panels and battery bank and takes care of charging. There are two types of controller commonly found in vans and RVs: | ==== solar ready ==== |
| |
| * [[electrical:solar:charge_controller#pwm|PWM]] - simple, inexpensive, cannot make complete use of the panels' capabilities. | RVs that are sold as "solar ready" typically have a connector and wiring from Zamp. It is more apt to call it "Zamp solar kit ready" as normal panels cannot be attached to the Zamp port. Here is [[https://www.forestriverforums.com/forums/f221/a-frame-solar-ready-71071.html#post740529|Zamp's description of Solar Ready]], which uses panels with built-in controllers. |
| * [[electrical:solar:charge_controller#mppt|MPPT]] - more complex, 2-3x more expensive, can run the panels at max power, optional with 12v panels and mandatory when nominal panel voltage is higher than nominal battery voltage.((e.g., 24v (72 cell) panels with a 12v bank)) | |
| |
| PWM are cheap enough that it is common to start with PWM and upgrade to MPPT later only if necessary. After one upgrades from the PWM unit it can be kept as a spare/emergency part. | It is been judged harshly by some users: |
| |
| Folks in areas of [[electrical:solar:output|limited sunlight]] (like the Pacific Northwest) or heavier power use might be better served by investing in MPPT right away. | > “Solar Ready” doesn’t mean sh*t. It means there is a plug wired to your battery and oh by the way IT IS WIRED EXACTLY BACKWARDS. The polarity on the Zamp SAE style connector is reversed. -- John's Tech Blog((https://www.hagensieker.com/wordpress/2020/01/12/rockwood-a122-two-year-review/)) |
| |
| |
| |
| | |
| | ===== rack mounting ===== |
| |
| | It is common to mount framed panels on a rack. This accomplishes a few things: |
| |
| | * allows the panels to always be deployed |
| | * 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 |
| | * to keep from drilling extra holes in the roof |
| | * allow changes later; drill new holes in the rack |
| |
| | 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. |
| |
| |
| |
| [[electrical:solar:status#is_my_solar_working|This information]] will help you tell if it's working or not. | [[electrical:solar:status#is_my_solar_working|This information]] will help you tell if it's working or not. |
| |
| |
| ===== muddying the waters ===== | |
| |
| Once you have a headlock on the information above it is time to [[electrical:solar:gentle complexity|introduce a bit more complexity]]. | |
| |
| |
