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DOMESTIC SOLAR TECHNOLOGY
Solar equipment usually has 4 components:1. the solar panels,
2. the battery bank,
3. charge controllers and
4. the inverter
The functions
1. The solar panel is responsible for converting solar energy to electrical.
2. The battery bank stores energy for use during the night or when there’s cloud cover
3. The charge controller regulates energy flow into batteries, hence protects the batteries from too much power
4. The Inverter converts 12V DC power to 220V AC power. Usually household appliances use AC power.
CALCULATING EQUIPMENT NEEDED
Calculating how much equipment we actually need requires three stages, namely:
Power Assessment, Power optimisation, Final calculations
Power Assessment
This involves figuring out how much energy you need to run your house. This obviously has to be known for us to proceed. Your requirements may not be similar to your next door neighbour’s since you may have an extra home theatre and your son has a computer in his room. If you have no electricity at all where you are, that means you don’t buy any units and you don’t receive any electricity bills.
So how do you calculate the amount of energy you need? Almost every gadget that you have in your house has a power rating or label on it. This may be in the product’s front or at the back. The amount of energy the product consumes is equal to its power rating times the number of hours the product is actually ON. In the case of an 80W bulb that is switched ON for 5hrs daily. This bulb alone consumes (80W x 5hr) 400Wh worth of energy.
When using this method one has to go through their whole house noting down each component that uses electricity, its power rating and the number of hours it is switched ON during the day. After this you multiply all power ratings times their hours of use. That leaves you with energy consumption per each gadget. Lastly you add all the energy consumptions to get your total daily consumption.
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The power ratings and hours of use above are rough estimations.
Now, having completed power assessment, the next stage is power optimisation.
Power Optimisation
Power optimisation is just a fancy way of saying let’s cut down our current consumption by
getting rid of some huge energy “gobblers”. These energy gobblers consist of things like stoves,
microwaves, geysers and anything else that has a power rating over 800W. Simply find an
alternative for it, e.g. in place of an electric stove use a gas stove, in place of an electric geyser
buy a solar one (yes water does boil in them), and in place of a microwave, use a gas oven.
These
energy gobblers have to be removed otherwise you will cover your whole roof with solar panels.
However some energy gobblers are impossible to remove hence we need to content with them,
for now. Examples of these are borehole pumps and booster pumps. Well let’s just power them
up with solar until someone invents something new.
Replace less efficient products with more efficient ones. A refrigerator will consume more and
more energy when it grows older, you have to either service it or replace it. Lights are also an
easy target. What’s important for a light is the lumens/watt. This shows how bright it becomes
per wat. If you still have tungsten lights, replace them with either energy savers, or LED lights
they have more lumens/watt.
Now that we have optimised our consumption, let’s calculate how much of the solar equipment
you actually need.
Final Calculations
EQUIPMENT FOR A DOMESTIC SOLAR SYSTEM
1. Solar panels
Solar obviously converts energy during the day, calculating the amount of energy it consumes is
a matter of multiplying its power rating times the number of hours it is exposed in the sun times
its efficiency.
Solar’s energy = Solar panel power rating X hours of exposure X solar panel’s efficiency
A fixed solar panel is actually exposed for approximately 6 hours during the day. Yes I admit
that a day has more hours than that but when the solar is fixed it doesn’t turn to face the sun
hence when the sun is at an angle the solar absorbs less energy than when it faces the sun
directly. Clouds are also other factors to consider. So 6 hours is the average time the solar
converts energy at a rate equal to its power rating.
2. Solar batteries
Batteries are measured in Ampere hours (Ah). For you to be able to store energy you convert
during the day you need batteries that are big enough to contain that energy. So figuring out how
many batteries you need is a matter of determining how much energy a single battery can hold.
This of course is easy. You just multiply the batteries Ampere hours (Ah) times the voltage the
battery provides. Many batteries sold in Zimbabwe are 12V batteries. So let’s figure out how
many batteries Mr. Moyo needs to store his energy: Energy storable = Ah X Battery voltage
3. DC to AC converter (Inverter)
This is the unit that converts your stored DC power to AC power that is usable by the household
appliances. Its rating has to be equal to the maximum power that needs to be satisfied at a given
instance. For example, Mr. Moyo has all four of his lights ON between 6p.m and 10p.m, during
this time he also watches TV, he also plays a slideshow on his laptop while it charges, at the
same time his child takes time off from homework and plays on the desktop machine. Thus this
for him is the time for maximum power consumption. So his converter needs to be big enough to
satisfy this demand at any given time. Inverter’s power rating = the sum of power ratings that can
be used any given time.
Inverter’s power rating = Lights + TV power + Laptop + Desktop.
4. Charger controller
This is the unit that regulates energy as it flows into the batteries. You need it because your
batteries might get overcharged or receive too much power at one time. If they break batteries
are expensive to replace.
Charge controllers are measured in Amps. How do we determine the amperage (number of
amps) of the charge controller that we need. Solar panels come with amperages written either on
the packaging or on the back of the panel. The charge controller that you need must have
amperage equal to that of the solar panels added together.
Solar has become the future of household energy.
Let electricians help you today with all your solar installation needs.
Call or Whatsapp +263784259955 or +263779121253 and +263778726821
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