Off-Grid VS Hybrid Grid Tied Systems vs Pure. What is best

What Is An Off Grid System

In an off-grid system there is no public electricity grid. Once solar power is used by the appliances in your property, excess power will be sent to your battery bank. Once the battery is full it will stop receiving power from the solar system. When your solar system is not working (night time or cloudy days), your appliances will draw power from the batteries. One of the greater disadvantages with this system is that once the power from the batteries have been consumed one will require a back up source of power like a generator not only to power appliances but also to recharge the batteries themselves when sunlight is not available.

What Is A Grid Tied System

A grid tied systems is an electrical circuit that is tied to the public electrical grid, in this case Eskom. Essentially there are two types of grid tied systems which one can consider as “true” grid tied and hybrid grid tied systems.

The main difference here is that the “pure” grid tied system does not require batteries and uses only the inverters to change the DC current into AC current that can be used to power appliances. Once the energy stored in the system has been used the public grid supply will kick in. This is  the cheapest option available, as the PV panels and inverter (along with fuses, disconnect switches, breakers, grounding equipment and surge protection) are the only equipment necessary.

Please take note, a “pure” grid tied system is designed to supplement only day-time electrical usage. The main disadvantage with this system is that during a power outage or load shedding, one is still left in the dark. Inverters switch themselves off during a power outage and to stop the feed of any electricity back into the grid it as it poses a risk to repair people who may be working on a damaged grid. This is the most suitable option, if you have not battery back-up for commercial operations that have the bulk of their electrical consumption during daylight hours only who do not reply solely on solar.

What Is A Hybrid System

A Hybrid Inverter is an inverter which can simultaneously manage inputs from both solar panels and a battery bank. This means the system can charge batteries with either solar panels or directly from the electricity grid (depending on which is more economical or preferred). Their capabilities may go much further beyond this as technology evolves however – some devices can also handle inputs from wind turbines, generators and other more modern power sources.

With a hybrid set-up, batteries form part of the system and most have the ability to “island” – which means that they can isolate from the grid when there is a power outage or load shedding and still provide some electricity. This stored electricity will last as long as the combination of and number of batteries and devices consuming electric.

A hybrid PV system, gives you the best of both worlds.  The inverter in this system typically backs up and discharges electricity less frequently and this extends the life of the connected batteries. The significant advantage with a hybrid grid tied systems is that they allow one to add more batteries at a later stage. Unless there is stored power in the batteries during a power outage or load shedding, you will not be able to power on the lights and appliances you may need.

Remember to employ a profession who is certified to work on implementing such solutions who will correctly configure your installation to ensure that your critical load requirements are met. Your higher electrical consuming appliances such as a geyser, stove, oven and kettle should be connected to their own solar supply so that you can save more on your electrical costs.

A hybrid system is a fair amount more costly than a grid-tied system as you need to purchase an expensive array of batteries for your battery bank.

Since a hybrid solution is capable of storing power it is possibly the best option to consider. Our local national power supply is unrelaibale and the future of our electricity supply is inconstant and forever changing and becoming more and more expensive. From the 1st of April our electricity costs sky rocketed making solar a more viable option in the long term. Find out more about this here.