Monday, February 9, 2015

Powering my home by Solar Energy

I am interesting in renewable energy area from my childhood. Sri Lankan government introduced grid solar power system for residential few years ago. I was able to install grid solar power system at my home in 2014  with my uncle's help who has great knowledge about electric systems.

Mainly there are two types of Solar Systems i.e off grid and grid tied.

DC off grid system

rarely use [most electric components are capable only for Alternative Current (AC)]


AC off grid system

Inverter converts Direct Current (DC) to Alternative Current (AC). You can use a generator if you want to get power when battery bank is dead.

grid system with batteries

With a Battery bank you can have current to your home when distribution line power cut. you cant do that without a battery bank. because extra power should be store somewhere (in a battery bank).

grid system with batteries

I am using this system (without a battery bank). At Day time we are using the solar power and rest sends to the distribution line (export). If the solar power is low then get the current from normal distribution line (import).  

Lets say you have exported 300 units at the end of month and imported 400 units, so you have to only pay for 100 units. Otherwise (export = 400 , import = 300) then you have extra 100 units in your hand and you can use that extra units at other circumstances (some months have rainy season so import units can be higher)

There are 24 solar panels at my house's roof, each panel produces 185W to power up my home by solar energy. setup is not much difficult. It is similar to normal battery setup. Lets say you have two packs of 12 batteries. 12 batteries of each pack is connected series. 2 Packs gives powers separately.

grid solar system circuit diagram at my home

Be carefull
There are two types of solar panels in market i.e. monocrystalline and polycrystalline. Make sure to buy monocrystalline solar panels though it has high initial cost.

Currently I am getting 20 units average (20 kwh) for a good sunny day. For a rainy day its reduced to 10 units.

In my home roof is faced to East and West. For this kind of scenario best way is to have two sides are separately to produce power. Morning to 12'o clock Right hand side produce much energy than left also 12'o clock noon to Evening left produce much than right. If we put all sets as one it will drop the production.


Lets say Morning to 12'o clock Right hand side produce average of 1900 W and left is 1000 W, total production is 2900 W (1900+1000).

if we set both side as one, total production will be reduced to the minimum side

production = minimum {Left , Right} * 2 = 1000 W * 2= 2000 W

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