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electrical:solar:gentle_intro
A good solar system is one that meets your needs. – jimindenver1)
“…trying to take the comfort level you had in a house into your mobile life [is] tough to do for a boondocker.” – akrvbob2)
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

A gentle introduction to solar

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.

If you would like a refresher on basic electronics, see the AltE Intro to Electronics for solar video.

Benefits of solar

Solar power is silent, works for decades, and is always working when the sun is shining.3) It can recharge your batteries and run your loads.

Solar is nearly mandatory for charging lead-chemistry batteries off-grid, since those require of many hours of charging.4) Failure to charge lead batteries5) fully and regularly leads to battery murder. Solar helps prevent battery murder and the resulting $$ battery replacements.

For people who can 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.

Limitations of solar

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 a residential (or campsite) outlet with a $20 extension cord. Over time, though, the power is “free”.

Getting some power from solar is easy. Getting reliable power from solar alone is challenging (and expensive) because solar harvest is greatly affected by 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.

How solar power works

Solar power uses solar panels to convert sunlight into electricity. This electricity goes into solar charge controller, which keeps the battery optimally charged6) and powers any loads (things that consume power). The controller extracts the exact amount of power your batteries+loads demand and no more: in effect the controller is pulling rather than the panels pushing.

Overall it is arranged like this:

  panels -> controller -> battery bank -> loads

Power is stored up in a deep-cycle "house" battery during daylight and the power is pulled back out at night. The house battery is electrically separate from the vehicle's starter battery.7) In broad terms…

“Think of the batteries as a bucket of electricity. It's possible to pour water from multiple sources into a bucket at the same time, and also to do that while water is leaking out of the bucket.” – MarkSF8)

Battery charging is a topic unto itself, and improper charging can kill batteries prematurely.

Since it looks like magic, beginners tend to worry about 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 constantly9) 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.

Your approach to solar

Since reliable power by solar alone is tough, there are a few approaches to consider:

  • best-effort power - you take what you can get from the sun and 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.
    • massive solar - You can still collect usable solar power under very poor conditions if you have a huge amount of panel. This may require “maxxing out” your roofspace, tilting the panels, or deploying additional portable panels. Such configurations may be 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 non-essential loads without affecting your battery bank's state of charge.
    • solar + other forms of charging - Solar can work much better when augmented by additional sources of charging. It can work so well that less solar might be required and overall cost reduced.

How much solar do I need?

This question usually means “how much power do I need?” and involves making power10), storing power11), and using power12). 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.

It's not fun but the first step in getting solar is to assess your daily power requirements. Until they sit down to do the math first-timers often have radically unrealistic ideas about power in the campervan. You probably won't be able to run a hair dryer, electric space heater, air conditioner, or instant pot from solar.

Note: you can get a ballpark idea before crunching your own numbers by reviewing some existing solar installs.

Why daily?

Power requirements are calculated daily because the solar feeds the batteries13) only in daylight. Then at night the system pulls power back out of the batteries. This is natural rhythm of a solar-powered system.

A minimal solar configuration will

  • 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

People who are off-grid for longer stretches will also have to think about 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.

Should I build or buy solar?

In order from traditional to more recent approaches

DIY

DIY (do it yourself) means selecting component components individually (panels, solar charge controllers, batteries, inverters, isolators, etc) and installing them yourself.

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.

Con: Time-consuming. You have to learn enough to pick components and install them.

Kits

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

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.

Portable power stations

Often called 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.14)

Pro: all of the product selection is outsourced for you. Portable and generally attractive package.

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.

solar ready

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 Zamp's description of Solar Ready, which uses panels with built-in controllers.

It is been judged harshly by some users:

“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 Blog15)

Is my solar working?

One of the challenges of learning solar is that until you understand how it works it can be difficult to be confident that it does work.

This information will help you tell if it's working or not.

electrical/solar/gentle_intro.txt · Last modified: 2022/05/13 10:56 by frater_secessus