The Survivalist’s Guide to Solar Power

When it comes to off-grid living, it is the thought of going without electricity that gets to most people. This is what makes people scramble to buy pricey solar panel systems and keep them attached to the grid “just in case.”

Let’s think about this rationally.  How much do you really need electricity?

You Don’t Really Need Electricity

Sure, it is nice to have a TV, internet, washing machine, dishwasher, and all those other appliances in your home.  But they also take up lots of space, are noisy, are distracting, and generally build up your anxiety levels.

I personally think that the best test to see how much you really need electricity is to spend a few days camping off-grid.

It only takes a day or two in nature before your body gets in rhythm with the earth.  You rise with the sun and go to bed when it gets dark.

You don’t get bored without your TV and gadgets because you are actually talking with your family.

Reasons You’ll Still Want Electricity

While you don’t need electricity, there are some areas of your life where electricity is particularly useful.  I wouldn’t want to completely give up electricity for:

• Refrigeration and Freezing: There are off-grid solutions like root cellars and iceboxes, but these don’t quite compare to a fridge/freezer for keeping food fresh.
• Lighting: Sometimes you need to do things at night and having lighting can increase your productivity hours.
• Power Tools: When living off grid, you’ll probably need to use your tools a lot more often. While there are hand-powered tools, they aren’t nearly as powerful as ones that use electric power.
• Internet: While not absolutely essential, having access to the internet means you have access to information – and that can be essential!
• Communication: Unless your entire family is going off grid with you, you’ll probably want a way to call them and that will probably require electricity.

There are three main options for off-grid electricity: Solar, Wind, and Hydro.

Wind is very impractical and expensive for home use, and hydro is only a solution if you live near a source of moving water that you can divert.

So that leaves solar power as the best option for most people.

Calculating Your Solar Power Needs

The first step in getting started with solar power is to know what your power requirements are.  For most households in the USA, this is around 900 kWh each month.  You can easily check this by looking at your monthly electric bill.

Next, you need to be aware of how much sunlight your area will get.  This obviously varies by region as well as by season.

In Southern California, for example, you can expect about 6 hours of sunlight per day in summer and 3.4 hours in winter.   In Upstate New York, you can expect only about 4.5 hours of sunlight during the summer and 2.3 during winter.

Once you know this, you can do some math to determine the size of the solar panels you will need.

How to Calculate Solar Panel Size

• Take your monthly energy use and divide it by 30 days. This will give you how much energy you need per day.
• Divide this number by the sunlight hours in your area. If you will be relying on your solar system year-round, then divide it by the lower sunlight hours in winter.

For example:

Let’s say that your family is fairly good at conserving energy so you use about 600 kWh each month.  That comes out to 20 kWh per day.  If you live in an area of Texas that has 4.5 peak sunlight hours during wintertime.   Divide 20 kWh by 4.5 sunlight hours and you need 4.44 kW worth of solar panels to meet your winter power needs.

Even though solar panels are getting a lot cheaper, they are still pricey to buy.  The simplest way to reduce the upfront costs of solar panels is to reduce your energy needs.  The less electricity you use, the fewer solar panels you will need.

This is in line with the off grid mentality which says that “less is more” and encourages a more hands-on approach to the household.

For example, do you really need to waste all that power to run your washing machine when you can get a pedal-powered washing machine instead?

4 Main Parts of a Solar Panel System

Once you know how much energy you require to use solar off grid, you can start designing your system.

Here we will go over the 4 main parts: Solar Panels, Charge Controller, Battery, and Inverter.

1. Solar Panels

There are two main types of solar panels: Crystalline and Thin-Film. Crystalline are currently the more popular option and have a longer lifespan.  They are also cheaper than Thin-Film solar panels. However, crystalline panels are heavier and require a more complex racking system to install them.

Solar panels can also vary drastically in how much energy they generate (aka Conversion Efficiency).  If you only have a small space for collecting sun energy (such as a small rooftop), then Conversion Efficiency matters and you’ll need to buy more expensive solar panels that can produce more energy.

There are also numerous other factors to consider like LID and PID resistance, temperature co-efficient, tolerance, warranty, and, of course, the cost. Here is a good guide to how to choose solar panels.

2. Charge Controller

The next part of a solar energy system is the charge controller, also sometimes called a “solar regulator.”  This prevents the batteries from overcharging when there is a lot of sun and energy going into the battery.

It is important to choose a quality charge controller as this will improve the performance of the battery and improve efficiency.

Here is a guide on how to choose a charge controller.

3. The Battery

It is possible to create a solar power system without batteries, but you would only be able to use it while the sun was shining.  Thus, virtually all off-grid solar systems rely on batteries to store the solar energy for later use.

While solar panels get the most attention, choosing the right battery may be the most important part of your off-grid system.

First, you will need to choose a voltage for the solar system, which can be 12, 24, or 48 volts.  The benefit of going with a higher voltage is that there will be less energy loss. Most small off-grid homes use a 12 or 24-volt battery though.

It is possible to use a car or truck battery for a solar panel system.  These are okay for providing short bursts of high energy and then recharging them.  However, they are not meant for deep discharge.

You’ll more likely need a deep-cycle lead-acid battery that permits partial discharge and also for deep slow discharge.

Battery capacity is rated in Ampere hours. Remember that batteries are not 100% efficient so you’ll need to leave some margin when choosing an Ampere Hour for the battery.

Note that the battery choice really depends on how you plan on using the energy.  A battery that isn’t fully charged might not be capable of providing enough energy to power a large appliance like a washing machine.  The battery voltage might drop so much that the inverter cuts it to protect it – meaning that your load of laundry stops mid-cycle.

4. Inverter

Solar panel systems produce DC current.  There are now many household appliances specifically designed for solar use which run on DC current.  However, most still use AC current.  If you want to use your solar system for these appliances, then you’ll need an inverter to convert DC to AC current.   Inverters can be connected directly to the appliance or they can be connected to your breaker panel.

Other Components

Those were just the 4 main components of an off-grid solar panel system.  You will also need other equipment like wiring, fuses, breakers, disconnects, and battery monitors.

You may also want to consider wind and solar hybrid systems.