An off grid solar power system consists of:
Solar panels
PV combiner
Solar charge controller (PWM or MPPT)
Battery (Gel or lithium battery)
Off-grid inverter
Cable and accessory
Solar panel bracket according to different roof or ground

The first thing is to calculate the inverter power. To see how big the inverter and what is the DC voltage for the system.

To determine the inverter size we must find the maximum wattage of your home.
You can found this by adding up all your home appliances that would run at the same time.

Example: A room has three 60 watt lights and a 300w TV. The inverter size is 60 x 3 + 300 = 480 watts

And we should use at least a 500w inverter to run the appliances or 1kw would be better. Never full use the power of the inverter, because if you use full load all the time, the inverter life span would be reduce.

For the home appliances like air conditioner, the working power would be 4-6time than rate power, the inverter power should be consider bigger.
Like a 750w air conditioner, the working power would be 3kw-5kw. You should use a 5kw inverter to handle the air conditioner.

And also for the pump, the start power may reach 4times, so if your house have pumps or air conditioners, the inverter power should be bigger.

There are 2way can size your solar panel power.

First way is to see your electricity bill, if you use 900kwh per month. Then each day is about 30Kwh. How many solar panel can generate 30kwh in one day?
Usually we use 6 hour for efficient sun hour. And solar power can not 100% use, we consider 0.7 factor as the efficiency.
Here is how to calculate the solar panel power

So you will need 7kw solar panel to cover 900kwh per month if you not consider the rainy and cloudy day.

And the other way is to estimate by yourself.
Example: A room has three 60 watt lights and a 300w TV. Lights working hours is 12hours, and 9hours for the TV. Then the total usage would be

Here is how to calculate the solar panel power

So you will need 814w solar panel to cover the total usage if you not consider the rainy and cloudy day.

Finally we can size the battery bank capacity.
Example, there is one 500w machine working 24 hours, then we can divide the 24hours into 6 hours in day time+18 hours at night.
The battery bank is for night use. Then the total usage at night would be:

If we use 50% DOD for the battery, and the inverter voltage is 96V.
Then the battery bank should be

Because for the gel battery, common DC voltage is 12V.
So in for the 96V system, it will require

And the common gel battery capacity is 100Ah, 150Ah, 200Ah, 250Ah.
Then we will need 8pcs 200Ah gel battery for running 500w machine work 18hours at night.

Solar panel bracket according to your need.

The cost of an off grid solar power system can vary widely depending on the battery number and the solar panel number.

In general, the larger the system and especially the larger the solar PV panel and more battery, the larger the price tag.

When considering the true cost of an off grid solar power system, it can be helpful to compare same power inverter and same battery number and solar panel number.

For example, one 5kw off grid solar power system, the price would be quite different from one with 4pcs battery and the one with 8pcs battery.

From all the time, people trying to use the sun power as resource.
The first recorded is solar pump system, which were developed in the 19th century.

These first pump was used sun heated water to create steam, and use the steam to drive the steam engines. This was as a result of technology to convert solar energy into other energy forms.

These steam engines powered water pumps, trains, textile machines, and began the machine revolution.

In the 1960s, the solar panels were very inefficient, because the materials is hard to process and rare. It made the solar panel cost very high, like around $1000 per watt. This is like a impossible price for civil.

Luckily, the prices of photovoltaic (PV) panels have dropped a lot, because the price of silicon, the key material has also dropped substantially.

Choosing between different types of solar power system is not difficult, you can choose according to your appliances.

Bob is one of  the creators of InkPV. He uses experience in marketing and knowledge from her master's in climate communications to research and review the solar and wind industry.