# How to Design a Domestic Solar Photovoltaic System Our solar system. The solar panels are – 5 x 190 watts + 1 x 300 watts + 2 x 150 watts

# INTRODUCTION:

If you are thinking of installing a solar energy  system in your off grid home it is very important to understand the basics of system design. It is best not to leave all the decisions to a salesperson.  It is very important to make the right decisions about battery size because old batteries cannot be mixed with new ones. So it it will not be possible to buy some supplementary batteries if you don’t have enough.

# 1. Calculate how much power you use

You have to find out how many kilowatt hours you use. A kilowatt hour or kWh is 1000 watts used for 1 hour.For example  If you have a 2000 watt fire on for 2 hours it will have consumed 4 kWh.
If you have an on-grid house the  electricity bill from the electricity company states the amount of kWh that you have used. This could be a way of finding out how much electricity you use although it is very likely that you would be much more generous in your use of electricity  if you are on-grid.  Another way to find out how much energy you use is to use devices to measure electricity use. If these are not possible you will have to calculate your daily kWh by making a list of all electrical devices  and calculating their energy use. If you want to know exactly how many watts each device uses it is possible to buy a plug-in  Electricity Usage Monitor. You plug the device into it and it tells you the amount of watts being used.

To calculate the daily kWh  use this formula.
(hours used X watts) divided by 1000 = kWh

# 2. Find out how much sunlight you get.

To be continued…..
I also wrote a calculator to help you decide what you need.
http://crazycalculations.com/solar_power/index.php