Off-grid solar installations are a great solution for powering your remote vacation cabin or RV, for those living in areas with an unreliable power grid or for anyone wanting to live completely grid free.
Things to Know
When deciding how big of a system you need, you will need to consider your total power consumption. The average home uses 30kWh of power a day. You can determine your exact energy needs by adding up the wattage of your appliances, lights, etc.
This calculator will help you determine the equipment you may need once you have an idea of your energy needs: http://www.anycalculator.com/solarpanelcalculator.html. Another neat resource available online is https://sunroof.withgoogle.com/ which uses satellite images to assess your home and how many panels will fit on your roof.
Once you know how big of a system you need you can pick the right equipment for the job. The key components of every off-grid solar installation include solar panels, charge controllers, batteries and inverters. We offer a variety of complete packages of different sizes, or you can pick and choose the equipment that you want. If you are picking your own equipment, we recommend educating yourself properly on each component to ensure compatibility with your system and needs.
Below are the different things to consider when building your off-grid system.
Choose Batteries for Your Battery Bank
Off-grid solar systems rely on batteries to store energy produced from solar panels. There are 3 different types of batteries best suited for solar applications:
- Flood lead acid batteries
- Sealed lead acid batteries
- Lithium batteries
Flooded lead acid batteries are the cheapest battery option, but they also require the most maintenance. Flooded lead acid batteries contain a combination of a liquid electrolytes, and water must be carefully measured and maintained to ensure a healthy, long-lasting battery. These batteries also emit gases, so it’s important that they are kept in a well-ventilated location.
Sealed lead acid batteries require little to no maintenance and are more efficient than flooded lead acid batteries. Unlike flooded lead acid batteries, there’s no need to add water to the inside compartment. They are a little more expensive that flooded lead acid batteries, but they have a longer life cycle.
There are two main types of sealed lead acid batteries: absorbed glass mat (AGM) and gel batteries. Gel batteries, which use silica to stiffen the electrolyte solution in the battery, tend to have lower charger rates and output than absorbed glass mat batteries. They also can’t handle as much current, meaning they take longer to recharge. Gel batteries have a greater lifespan than AGM batteries. AGM batteries are the cheaper of the two and they also offer a better temperature range.
Lithium batteries are the most advanced and the most expensive battery type. They are compact and lightweight, have an extremely long life cycle and high discharge and recharge rates. They also require little to no maintenance. Lithium batteries typically have a lifespan of at least 10 years and lose less capacity when idle than other battery types.
The amount of battery storage you need is based on your energy usage, so it’s important to properly size your system before purchasing equipment.
Choose Solar Panels
Solar panels are the part of your solar system that do the initial work of collecting energy from the sun. There are 2 types of solar panels: monocrystalline and polycrystalline.
Choosing between monocrystalline and polycrystalline panels is one of the first steps to take when shopping for solar panels. Polycrystalline panels are light blue in color, and they are less energy and space efficient than monocrystalline panels. They are also the cheaper option. Monocrystalline panels, which are darker in color, are more space and energy efficient and are generally considered to be the more preferred option.
Solar panels are available in 12V and 24V. Home/cabin installations can be built to 12, 24, or 48 volt systems. Most RVs have 12V battery banks, so people typically use 12V panels in order to be compatible with the batteries. You may consider a 24V solar panel system if you have high energy needs. With any solar system, if your energy needs are 1 to 3 kW, we recommend a 24 volt system. If your energy needs are above that, you’ll want to install a 48v system. Having a higher voltage panel system can save you money in the long run as you need less charge controllers and can use thinner cables for the same amount of power.
Choose a Charge Controller
Charge controllers are another crucial component of your system and are recommended with every solar panel larger than five watts. They sit between the energy source and storage and perform the essential role of preventing any overcharging of batteries by limiting the amount and rate of charge to your batteries.
Additionally, charge controllers shut down your system if the stored power falls below 50 percent capacity and charge batteries at the correct voltage level. This helps preserve the life and health of the batteries in your battery bank.
There are two types of charge controllers to consider: Pulse Width Modulation (PWM) controllers and Maximum Power Point Tracking (MPPT) controllers. PWM charge controllers are cheaper and ideal in smaller applications. They’re an older technology and are therefore cheaper, but they are also less efficient than MPPT charge controllers. MPPT controllers are the most efficient controller option and ideal in large applications. Both controllers are widely used, have similar lifespans and preserve the life of your batteries well. We typically recommend using MPPT controllers in an off-grid system because of their increased efficiency levels.
Choose an Inverter
Inverters are the final, crucial component to consider when building your solar energy system. Inverters turn DC power produced from your solar panels and stored in your battery into AC power. An inverter is necessary to power most appliances found in your home or RV, from TVs to microwaves. When shopping around for inverters, you’ll quickly learn there is not a one-size-fits-all approach.
There are two main inverter types: pure sine wave and modified sine wave inverters.
Pure sine wave inverters are capable of producing smooth, quiet, and reliable electricity to operate appliances and electronics without any interference. Like its name suggests, pure sine wave inverters produce current in a pure sine wave shape. LAC Solar sells a wide power range of pure sine wave inverters. All these inverters provide overload protection for both DC input and AC output to prevent damage to the components and the unit.
Additionally, LAC Solar offers hybrid pure sine wave inverters. These are our most popular inverters because they combine the inverter and charge controller in one unit. This makes set up easier and creates less clutter visually wherever your equipment is installed.
When looking at the waveform from a modified sine wave inverter, it has a stair-step, square pattern, where the polarity is flipped back and forth. Because of the choppiness of the wave pattern, modified sine wave inverters can negatively affect more delicate, sensitive equipment. You will usually hear a hum with devices attached to a modified sine wave inverter. We recommend a pure sine wave inverter in most every instance.
Once you have decided to go solar, choosing your equipment can feel a little overwhelming. We hope that this guide has helped you get started on the journey. If you know the size of the system that you want to install, we have complete kits that make the process even easier and take the hassle out of choosing each component. Regardless of which route you take we hope you enjoy your new system, and welcome to the solar energy family!