When it comes to off-grid living, it is the thought of going without electricity which 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?
Are you interested in designing an off-grid solar system?
Here are the 6 steps to get you started.
1. Calculate Your Solar Power Needs
The first step in getting started with solar power is to know what your power requirements are.
This is the most important step, and many people try to skip over it. Don’t!
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.
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 which 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.
DIY Solar power may seem like a daunting task.
Fear not, this video WILL set you on the right path.
He start by unraveling the mystery of off-grid solar power and teach you the basics, how to understand and think about your system.
2. Calculate The Amount Of Batteries You Need
Now that you know how much power you need, you need to figure out how many batteries you need to store it.
- Do you need only enough storage for a day or two or do you need to have enough batteries to store 3 or 4 days, or more, worth of power?
- Do you have another power source, like a generator or turbine, that will kick in if the sun doesn’t shine?
- Will you be storing the batteries in a warm room or will they be in a cold location?
Batteries are rated for storage at around 80 degrees Fahrenheit.
The colder the room, the bigger the battery bank you need – by over 50% more for below freezing. Each of these answers affects the size, and cost, of your battery bank.
What voltage battery bank do you need – 12V, 24V, or 48V?
Generally, the larger the system, the higher voltage battery banks are used to keep the number of parallel strings to a minimum and reduce the amount of current between the battery bank and the inverter.
If you are just having a small system, and want to be able to charge your cell phone and power 12V DC appliances in your RV, then a basic 12V battery bank makes sense.
But if you need to power much over 2000 watts at a time, you’ll want to consider 24 volt and 48 volt systems.
Besides reducing how many parallel strings of batteries you’ll have, it’ll allow you to use thinner and less expensive copper cabling between the batteries and the inverter.
3. Select Your Solar Panels You Need
Once you know how much energy you require to use solar off grid, you can start designing your system.
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.
4. Choose Your 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.
5. Choose Your 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 which 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 which 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.
Here’s a good in-depth article about how to choose a battery for your solar power system.
6. Choose Your 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.
The price of the solar panels is getting cheaper, day by day.
The manufacturers are trying to make it more affordable, anyone can buy them and install a system for their home.
The installation of a complete off grid solar system is still costly, because hiring laborers almost never go down in price.
If you decided to build a solar panels system for home to cover your electricity bill, these 6 steps are a great place to start.