Hello
my name is Dwayne and I am seeking in assistance with designing a full off grid system total load 14720watts would like to design it to be expanded in future.
1.How many batteries are needed
2. Array configuration and quantity
For me, the first step in designing the system was determining what
and when the loads would be. This impacts how much production will be needed, and how much battery storage will be required to supply it. If the loads are not heavy during the non-solar hours, much less battery is needed, and, from what I have ascertained, the battery can easily be the most expensive component of the system.
So I would start by calculating the expected wattage of usage/loads, with an eye to the typical time of day for those loads. Then, in my case, to mitigate against cloudy days (for a completely off-grid setup with no option of public utility/grid as a backup), I doubled the battery capacity that I estimated would be necessary for one diurnal cycle. This should get me through at least one cloudy day without recharging. Then I added an additional 20% to the battery capacity to keep from cycling it too deeply. In the math, in other words, what I would actually draw out from the battery should not exceed .8C (80% of the battery capacity), as it is not good to run the battery to zero, even for LiFePO4 batteries (which I want to use).
Until you know your usage requirements, you are not yet prepared to make any determination of battery size, nor of paneling. If your peak usage coincides with peak solar production, you may be able to supply it from the panels without a large investment in batteries. Of course, remember that rainy days do happen--and only you will know how mission-critical your system must be. If it's okay to be out of power on occasion, it can make a big difference in your planning and budget as compared to majorly over-designing a system that is fail-safe even given a week of rain. In my case, the week of rain may be a reality, so I am hoping to use a generator as a backup for charging the batteries in those times (usually only about three-four weeks per year during rainy season).