Solar batteries store power generated from the sun and discharge the power as needed for later use. Portable solar batteries, off-grid or a simple backup rechargeable battery operates on fundamentally the same principles and many parts of the discussion can apply to both portable solar and fixed solar system. In a photovoltaic system, solar batteries in any type of form can experience a range of operating conditions and must be properly controlled to get the most from their performance, life cycle and more importantly, your safety.
It is a common misunderstanding that grid tied solar panels will operate when the grid is down. Inverters are designed specifically so that does not happen for a very good reason. Islanding is when an isolated electrical source is putting current back into the electrical grid. The danger is that a line repairman working in the neighborhood will unknowingly become injured because they thought it was safe to work on the line thinking the electrical power is off. Solar batteries can be a key component in stand-alone renewable energy systems, portable or fixed.
If never being without power is a top motivator for your system then you will need rechargeable batteries to provide the energy storage for your system. Deep cycle solar battery are designed to be discharged and recharged repeatedly. To maintain healthy solar battery and prolong battery life, most manufacturers suggest limiting the depth of discharge to about 20% but certainly no more than 50%. Below a 50% discharge can significantly lower the solar batteries life cycle. It should be noted that the term solar batteries overcharge may be used to describe two different conditions of battery recharging. The first of which is normal charging requires that more charge be applied to the battery than the expected gain once the battery is fully charged. This type of overcharge is necessary because some of the charge is lost through some battery inefficiencies. The second condition of overcharge applies to solar batteries that are already fully charged. If the charge is not stopped, the overcharge conditions can damage the battery, portable or solar battery in a permanently mounted solar or wind generator. The way to prevent over charging batteries is to use a charge controller which manages the energy that is flowing between electrical generator and battery or solar batteries.
Charge controllers use different methods to control the electrical current and voltage during the solar batteries charging. Single phase or stage charge controllers are simpler, but generally are more inefficient. For portable devices and smaller batteries they can provide the basics of that a charge controller should be doing. But multistage charging changes the applied electrical current to bring the battery to a higher stage of charge and is much more sophisticated sometimes requiring additional electronics. Multistage methods can charge batteries faster while limiting excessive overcharge and gassing minimizing safety issues. Often an inverter will have a Low Voltage Disconnect feature that will disconnect loads at a given set point. Low voltage alarms can provide audible warnings as well. Ammeters, voltmeters, solar battery monitors can help better maintain deep cycle battery health and provide statistics about the overall health of the system.
Types of Solar Batteries
There are many types of solar batteries each with its unique design, maintenance requirements and performance features. A solar battery is a collection of electrochemical cells that are contained in a case, sometimes wired together to produce a desired electrical voltage. Battery designs can vary by manufacturer but many share the same components and store electricity or power using similar processes. When selecting solar batteries you’ll have the option to use flooded lead acid batteries or sealed solar batteries which are commonly referred to as AGM (absorbed glass mat electrolyte) as well as lightweight portable solar batteries used for backpacking or camping.
Flooded lead acid solar batteries require a bit of maintenance, however, they generally last longer than their sealed counterparts. Devices such as water miser vent Caps can reduce the maintenance that is required when using flooded lead acid batteries. The other type of solar battery is known as gel celled batteries which are gelled by adding silicon dioxide to the battery solution. The mixture is added to the solar battery as a warm liquid that turns to get as it cools and is easily transported without the worry of spill. Finally there are common batteries such as alkaline batteries. Alkaline batteries such as nickel cadminum and nickel iron batteries also have positive and negative plates in an electrolyte. Each cell has a voltage of 1.2 volts and the charge termination point is 1.65 – 1.9 volts per cell. An advantage of an alkaline battery is they are as affected by high temperatures as other types of solar batteries.
Depending on the capacity of the batteries and the voltage of the charger, a portable solar battery charger can be powerful enough to power your laptop or notebook, while others work for smaller devices such as cellular phones, cameras, iPods, MP-3 players, flashlights, radios, and palm computers. In order to ensure you get the correct charger to run your equipment, you will need to get a charger with the correct voltage. For more information and guidance on how to determine the wattage you need, you can reference the solar power guide located at this link.
A solar battery charger allows you to charge batteries during the day, and then use them to power your equipment, during the night. Solar batteries also serve as a portable power source for appliances such as flashlights, radios as well as other portable solar equipment and have become a solution for hikers, campers, photographers, emergency workers, mountaineers, backpackers, bicyclers, horse-back riders, and anyone who will be away from the power outlets when they need to run or charge their electronic devices. Like other similar equipment, they can be used to run or charge laptops, cameras, cell phones, batteries, lights, MP3 players, GPS devices, and other electronic equipment. The advantage with a solar battery charger is that it can help you create and store power for later use. One can charge battery in the sun during the day, and use the stored electricity at night, indoors, or in bad weather.
Selecting solar batteries systems.
Solar batteries selection involves many decisions and sometimes compromises depending on conditions and usage. Some decisions on battery selection may be easy to make such a required capacity, size and or weight and cost. Each solar battery type has design and performance features suited for a particular application the least of which is cost. Solar battery may be a large expense for a sizable off grid system, with proper care and maintenance; they should last 5-10 years. Solar batteries for a portable solar application can be comparatively cheap, it still requires careful consideration.