You can calculate the size of the solar system and the number of necessary solar panels using a not so complicated algorithm. The numbers you have to put in the equation are your monthly electricity usage, the number of peak sun hours per day, and the power of a solar panel.
Calculating the solar system size for a 2000 kwh energy usage
To exemplify, let's start by assuming you need a solar panel system that can generate 2000 kwh per month. From the beginning, you should know that 2000 kwh per month is a quite a lot of energy, and you would need an impressive solar system to provide it. Although we use this number just for the sake of the exemplification, in case you do consume 2000 kwh per month, our advice would be to take some energy reduction measures and to remain connected to the electricity grid, just in case the solar system can not keep up with the demand.
Now, you have to find out for how many hours per day your system will be able to produce enough electricity for your needs. The panels produce energy only when the sun is up in the sky, and it shines directly on them. At night, the panels do not produce anything. In the morning and in the evenings, when the sun is weak, the energy production is also insufficient. Depending on the area where you live, there might be 4-6 hours of peak sunlight every day, when the system will produce the necessary electricity, and sometimes even more than you need.
If you want to have 2000 kwh per month, it means you have to produce 2000/30 kwh every day, that is 66.66 kwh per day. Considering there are 4 hours of peak sun every day in your area, the solar system will have to produce 66.66 / 4 = 16.66 kwh per hour, and that means 16660 in watts. Now, different types of panels produce more or less energy watts. If you opt for one that produces 150 watts, then you will need about 111 solar panels. Yes, that is a lot.
To approximate the necessary space for such a solar system, you have to know that, in order to generate 2000 kwh per month, you need a system of 24.8 kwp (kilowatt peak). Every 1 kwp needs about 100 sf of space.
It is, indeed, a large system, but if you want to save some money on bills, it is not necessary to build a system that provides all the energy you use. You can remain connected to the electricity grid, and build a system that supplies 30%, 40% or 50% of the energy you need, depending on your budget and available roof space.