Solar panels are made up of silicon layers and when light particles ( known as photons) from the Sun, hit the silicon layer knock off electrons causing them to flow hence generating electricity.
The sun is a natural nuclear reactor that releases small packets of energy called photons that travel the 150 million Kilometers from the Sun to Earth in about 8.5 minutes. We get enough photons hitting the surface of the Earth generate enough solar energy that can supply the global energy needs for a year.
Acording to the Internatonal Energy Agency (IEA), solar power is now the cheapest form of electricity.
Types of photovoltaic (PV) panels
There are basically three types of photovoltaic solar panels , monocrystalline, polycrystalline and thin film solar panels. Monocrystalline solar panels have solar cells made from a single crystal of silicon, while polycrystalline solar panels have solar cells made from many silicon fragments melted together. Thin film solar cell is a second generation solar cell made by depositing one or more thin layers, or thin film of photovoltaic material on a substrate such as glass or plastic.
How do I know what size of solar panels I need?
The first thing you need to do to determine the size and number of solar panels is to calculate your load, that is the appliances that will run on the solar system. This is done by multiplying the wattage and number of your appliances by the daily hours of use. For example, If you have 15 lights of 11w that you use for 4 hours per day, the watthours for you lights will be 11 x 15 x 4 = 660 watthours. You then move to the next appliance say a tv of 100w that you watch for 5 hours a day and have 100 x 1 x 5 = 500 watthours. You then proceed with the same procedure for all the other appliances and get the total in our case we have 660 watthours + 500 watthours which gives 1160 watthours.
From there, you divide the total watthours by the average sun hours in your region which is 5 in Kenya and add a factor of 20% to cater for the losses. You will therfore have 1160/5 x 1.2 = 278.2 w
Then you determine the panel size you want to use say 120w and divide it by the wattage established above which gives 278.2 / 120 = 2.31 and round off to the higher number which gives you 3 x 120w panels.
Frequently asked questions on solar panels
- What is the payback period of a solar system?
The payback period depends on many factor weather you have a battery back up and the type, how often you use the system , the type of equipment you purchased but typically 3-4 years for domestic systems.
- How long will my solar panels last?
Solar panels have a lifespan of 25 to 40 years and should be able to pay back the cost of the system and run for decades longer giving you free energy from the Sun.
- What happens to my solar system when It rains? will it still generate power?
Solar pv systems require light not heat to generate electricity however, the amount is reduced due to reduced radiation that is why you require a battery back up and days of autonomy factored in the system to cover for that so you will still have electricity.
- Can I add or scale my system later?
Yes you can add solar panels and batteries to your system but you require to have that in mind when procuring the original equipment.
- Can I use a fridge, microwave, blender or iron box with my system?
Yes, you can use the above appliances as long as the sizing of the system factored the in. However, for hot water heating, we recommend a solar thermal hot water system for water heating.
- Are all solar panels, inverters and batteries the same?
No. The type and quality makes a huge difference in the functionality and durability of a system. Only procure form a reputable firm dealing with quality brands.
- Will my solar panel work at night?
Solar panels do not generate electricity at night due to the lack of light from the Sun, however , a properly sized solar system with a battery bank will run throughout the day and night.