The first thing that anyone that's planning on going off-grid or trying to save money with solar panels needs to understand, is that it's a lifestyle change. Solar panels can only provide power when there is sunlight, this means that your savings would only occur during the day time, thus also meaning that heavy power usage items, such as geysers, ovens and kettles should only be used during the day. An example of this is that if you are used to cooking with your oven in the evening, then you would need to adjust your lifestyle such that you would only use your oven in the late afternoon for instance, when there is still sunlight, otherwise you would still be drawing power from the grid and not from your solar panels, thus not saving you anything.
The same goes for off-grid systems. An off-grid system usually refers to an array of solar panels with a backup battery solution. Your solar panels would charge your batteries during the day and you would use the batteries to power your lights, TV, fridge, etc. at night. However, most batteries are not meant to power power-hungry appliances such as ovens and geysers, as the large power draw tends to drastically deteriorate the lifespan of your batteries. Thus the same lifestyle changes mentioned earlier would apply to this type of system.