Off grid – Guide for independent solar power plants
Installing off grid solar power plants independent of the electrical grid is often the first thing people think about when they decide to go solar. While this option is definitely not for everyone, off grid solar power plants can be a great solution for those who live in remote areas without a reliable and affordable electricity grid, those who want to live a self-sufficient lifestyle without monthly utility bills, or have the need for access to energy during power outages.
Introduction to off grid solar power plants
Off grid solar power plants use batteries to store energy produced by solar panels. Since you rely solely on your own solar plant to meet all of your energy needs, systems must be sized and designed to meet different needs throughout the year, especially in the winter when there are fewer hours of sunlight.
Off grid systems are excellent for those who want to be independent of the electricity grid or do not have the possibility to connect to it. The key parts of any off-grid solar power plant include solar panels, charge controllers, batteries and inverters. We highly recommend that you take the time to read all about these different components, as well as the most important part, how to plan and size your system to be efficient for years to come.
This is because you will not be able to use the mains, but will rely solely on your own system. An accurate understanding of your energy needs will give you a better idea of costs and ensure that you do not build a system that is too small or too large.
Selection of batteries
Batteries are a key link in an off-grid solar system, and proper selection plays a key role in its longevity and efficiency. There are different types of batteries, each with its own characteristics and advantages.
Lead-acid batteries
Flooded lead-acid batteries
These classic batteries are an economical option, but they require regular maintenance and good ventilation. Liquid electrolyte must be carefully monitored to ensure a long-lasting and healthy battery. Lead-acid batteries are widespread and available in many stores.
Sealed lead-acid batteries regulated by a valve
Sealed lead-acid batteries, also known as maintenance-free batteries, are divided into GEL sealed batteries and AGM sealed batteries. They are more expensive than flooded lead-acid batteries, but do not require water topping up and have a longer life cycle.
| GEL | AGM |
|---|---|
| More expensive | Cheaper |
| More suitable for weaker currents | More suitable for higher currents |
| Lower charging speed | Faster charging speed |
| Lower temperature range | Wider temperature range |
| Greater discharge capacity | Lower discharge capacity |
LiFePO4 (Lithium-Iron-Phosphate) batteries
LiFePO4 batteries are considered the most advanced and most expensive type of battery. For those who value efficiency and portability, lithium-ion batteries are an excellent choice. They are compact and light, have an extremely long service life, high discharge and charging rates. Also, they require little or no maintenance. Lithium-ion batteries typically have a lifespan of at least 10 years and lose less capacity when idle compared to other types of batteries.
Conclusion on batteries
When choosing batteries, it is crucial to consider factors such as capacity (expressed in kilowatt-hours), charge and discharge cycles, and operating temperatures. Lithium-ion batteries tend to have a higher initial cost, but provide better value in the long run due to their longevity and efficiency.
Selection of solar panels
When you decide on a solar system, it is crucial to choose the right solar panels, because they are the heart of the entire off grid system. Different types of panels are offered, and the right choice depends on specific needs and conditions. Here are some key factors to consider when choosing solar panels.
Monocrystalline vs. polycrystalline panels
Monocrystalline panels: more energy efficient, darker in color and with a higher price
Polycrystalline panels: less energy efficient, brighter colors and more economical
Flexibility vs. firmness
Solid panels: standard type and more durable, ideal for roof installations on flat surfaces
Flexible panels: lighter than rigid panels, perfect for mounting on curved roof surfaces
Folding panels: multiple applications, lighter and portable, suitable for limited space, for lower energy needs
Panel voltage
The choice depends on the energy needs. Smaller systems often use 12V panels, while larger systems are more efficient with 24V or 48V panels. If the energy needs are between 1 and 3 kW, a 24V system is recommended, and for more than 3 kW, a 48V system. The higher the voltage, the faster the charging speed.
Selection of charge controller
Charge controllers are an essential part of any off grid solar system. Their key role is to prevent overcharging of batteries, limiting the amount and speed of charging. In addition to the above, they ensure the longevity of the batteries.
We distinguish between two types of controllers: pulse width controllers (PWM) and maximum power point controllers (MPPT). PWM controllers are more economical and suitable for smaller systems, while MPPT controllers are most efficient in larger applications. In off-grid systems, the use of MPPT controllers is recommended due to increased efficiency.
Choosing an inverter
Inverters are the last but crucial component to consider when assembling an off grid solar system. Their role is to convert the direct current (DC) from the solar panels and stored in the battery into the alternating current (AC) needed to power everyday devices in the home or RV, from televisions to microwave ovens. When choosing an inverter, it is important to understand that there is no one-size-fits-all approach.
There are two main types of inverters: pure sine wave inverters and modified sine wave inverters
Pure sine wave inverters are capable of producing reliable electricity to operate devices without any interference. As the name suggests, pure sine wave inverters generate current in the form of a pure sine wave.
Looking at the shape of the modified sine wave inverter, one will notice the stepped, square shape where the polarity changes. Due to waveform irregularities, modified sine wave inverters can adversely affect sensitive electronics. If, for example, you are using sensitive medical equipment, it is recommended to use a pure sine wave inverter. In many cases, devices connected to a modified sine wave inverter can produce noise.
Modified sine wave inverters can be used in simple systems without sensitive electronics. If you’re running a device that doesn’t have an AC motor and isn’t sensitive equipment, you’ll probably be happy with a modified sine wave inventor. Old cathode ray tube televisions, water pumps and cell phone chargers usually work well with a modified sine wave inverter.
However, appliances such as refrigerators, microwave ovens, and compressors that use AC motors will not operate as efficiently with a modified sine wave inverter. Some fluorescent lights also won’t work as bright, and some may make noises like buzzing or humming.
Conclusion
Ultimately, this guide to off grid solar systems provides basic information for those looking to live off the grid. Understanding the components, from solar panels to inverters, is necessary to successfully assemble your own off grid solar system.
Proper sizing of the off grid system, from solar panels to batteries, is key to long-term efficiency. Choosing batteries, such as lithium-iron-phosphate, brings advanced efficiency and long life, while choosing an inverter, especially pure sine, is key to reliable energy.
Charge controllers and careful selection between PWM and MPPT ensure optimal battery charging. The versatility and efficiency of the system depend on the precise selection of solar panels, whether they are monocrystalline, polycrystalline, flexible or fixed.
Through this off grid guide, we provide the basics for an energy-independent life, promoting sustainability and reducing harmful impacts on the environment. By following the steps and adapting them to individual needs, everyone can realize their dream of off-grid living with a powerful, efficient, and sustainable solar system.
Feel free to contact us for more details and all inquiries related to battery and solar systems.