Solar batteries and how best to use them

The key challenge to using solar PV power is energy storage – what to do when the sun does not shine. We have to find a way to store the solar energy that our PV produces during the day, so that we can use it to power our televisions and appliances at night. This storage comes in the form of batteries.

These batteries are called deep-cycle batteries and are very different from other batteries. For example, you cannot use the same type of battery that you have in your car. Your car battery is designed to put out a large current for a very short time to start the engine and it is recharged by the car itself, giving it a long lifespan. Deep cycle batteries give off a much smaller current than the car battery but they need to maintain it for a much longer time, usually from the time you arrive home after work until the time you go to bed – usually 2 to 3 hours after sunset. Therefore, deep cycle batteries are much more expensive than the average car battery. In a home installation, batteries will be charged during the day using solar energy or mains energy and will be discharged (providing energy) after the sun has stopped shining.

If you are a company that only needs to use power during the day then solar PV power without the use of batteries may be an ideal solution. However, on prolonged rainy days or where energy is required after hours, energy may need to be stored to work the entire night for lighting, security or night shift. As in the home installation, batteries will be charged during the day and discharged at night.

Some key considerations in using batteries in a solar PV installation are as follows:

  • You cannot just connect a few batteries to your rooftop PV panels and disconnect the grid power. These batteries may provide solar generated power but they have limitations and restrictions. First, a charge controller needs to be installed to make sure that your solar batteries aren't being overcharged …or being drained to the point of destroying a batteries potential to hold a charge.
  • The power coming in from the PV panel is also rated in DC (Direct Current), this needs to be converted to AC (Alternating Current) in order to be compatible with your common household appliances. To achieve this you will require an inverter to ensure that the Dc current can be utilised and the rest of the power is sent through the inverter to become AC power. The system doesn't need you to switch over at different times of the day it will all happen automatically, as well as kicking over to normal mains power if the batteries become depleted. This prevents any appliances from having to be "rebooted" or in the case of computers losing valuable data.
  • Generally the only maintenance is monitoring the wear and tear of the batteries and a "service callout" is recommended every 6 months.

Please understand, in a residential environment it is not yet feasible to go completely off grid. Appliances like geysers and cookers are incredibly energy intensive, and Afri-Market offers other renewable solutions for this including high quality solar water geysers. It is also suggested that if you need to upgrade your cooker or you have the vision to reduce your energy usage long-term invest in a gas cooker sooner rather than later.

Please contact us to discuss your requirements.