Design Off grid Solar Photovoltaic System to Generate Electricity

With simple, brief and accurate method, Many People ask me about how can they feed their homes or commercial buildings with electricity from the off grid solar photovoltaic system . Kindly permit me to introduce you the answer in six steps as following:
 Step one: Calculate load kWh requirement for DC and AC electricity per day and indicate battery days of autonomy required by customer, which mean the number of days that our electrical load can be fed from batteries without the aid of the solar radiation
 Step two: Divide kWh for AC electrical load on inverter efficiency (let it 0.90) and add the result to kWh for DC electrical load then divide the result on 0.85 (efficiencies of batteries and charge controller), so the result is DC kWh that required from the solar photovoltaic array per day.
 Step three: Divide DC kWh required from the solar photovoltaic array which resulted from step 2 on sun hours per day for the location of the array (city and country), let it 5 hour for Egypt country , you will get minimum  DC kW required from array, select module power and calculate Isc & Voc incase of parallel and series modules connection. But try to select connection that will introduce low electrical current in order to reduce electrical losses
 Step four: Charge controller is a DC to DC converter and its selection is depending on photo voltaic array current and voltage. Voltage and current of array (Isc, Voc) mustn't exceed the voltage and current max input ranges of charge controller in order to achieve MPPT (maximum power point tracking). Charge controller specifications are briefly comprise (max current, max voltage, operational voltage (24/12 v) and if it precedes MPPT or not).t
 Note:charge controller have (2 inputs) from the solar photo voltaic array, 2 outputs to DC load continued to the 2 inputs to the inverter , 2 outputs to the batteries and it's duty is to regulate charging and discharging of the battery. Usually the output voltage of the controller is 12/24 V
 Step five: Select any battery spec and start to determine AH (ampere hours) of the batteries by dividing total daily DC kWh required by the total load on (battery depth of charge (let it 0.6) * controller charging voltage 24/12) and multiply the result by days of autonomy, for example let it 2 days
 Hint: AH of the total series batteries is the same for the one battery but if the batteries are connected in parallels, AH of the totals is equal to the sum of all. Also Battery depth of charge 60% mean that you can get 60% of battery charge without affecting its life time or its safety
:Step six : Indicate minimum inverter power rating, it will be depending on the AC kW load and equal to (AC kW load / efficiency)
At the end if you want to design off grid solar photovoltaic system to generate clean and reliable electricity, you can simply precede the six steps mentioned above and I will be very happy to answer your question and inquires.