Originally Posted by
Justloadit
It is extremely costly to go completely off grid.
One of the issues is that the use of hot water has to be carefully observed to get the most out of the sun based heating periods.
I have a dual geyser PV based water heating system, which is split between the kitchen and the bedrooms, giving me 300 litres of hot water every day with dedicated panels for this application.
Most days both 150L geysers end up at 65°C, however when it rains, I may get 40-50°C from both depending on the amount of cloud cover if all day or not.
I do have a mains back up when i require hot water. I usually set up the cut out at 50°C when running off mains, and has been adequate for my use.
Depending on the start temperature, I save between 7,5kW to 14kW per day.
My pool pump, which draws 1kW, runs of the inverter during the day between 10AM to 3PM when the sun mostly shines.
I then have a 5.5kW hybrid system with 10kW Lithium battery pack, and 2.6kW of PV panels.
I still use quite a bit of power from the grid, most days 50% solar, and 50% from mains. Totaling between 25 to 30kWH a day, when there is full sun shine whether winter or summer.
I could improve the amount from solar by increasing the number of PV panels and battery back up, so that less dependence on the grid.
I also have an 11kW generator as further back up.
I have noted a 50% saving on my mains bill.
My current cost for the hybrid and PV geyser is around R120K.
To go completely off grid, is far more expensive them maintaining some use from the grid.
Another very important point to note, that to get the best use of the PV solar water heating hot water storage, requires that the geyser be replaced with the latest models, and cladding all the pipes to and from the geysers, which have between 0.5 to 1°C of heat loss per hour, as opposed to the older geyser that use 3 to 4°C per hour, which greatly influences how long you can store the heated water, especially in winter.
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