We see a lots of people
installing solar rooftops in today’s time. But still lots of people are still
skeptical about going for solar rooftop. The main reason for that is the high
initial cost, which is scarring them away from the great benefits which solar
energy has to offer.
People who have gone for solar
rooftop are definitely witnessing their benefits and are also encouraging other
people to opt for it. We will be sharing here some of the basic things which
one needs to be aware of while choosing the right solar rooftop for their
needs.
Residential Solar Panels: An
introduction
Residential solar panels are either
monocrystalline, polycrystalline or thin film panels. All of them has their own
pros, cons and efficiency rates. In terms of suitability, monocrystalline and
polycrystalline panels are most suitable for residential application because of
their higher efficiency, longer life, etc.
Choosing the right solar panel for
your need
Lots of people has this common
question of which solar panel should they go for and for how many kW. For
residential application both monocrystalline and polycrystalline panels are
suitable. Choosing either single facial or bifacial solar panels will depend on
the amount of space available for the kW of solar panels you have chosen.
Bifacial solar panels will require lesser space.
Every household has different
requirements of electricity in terms of monthly and daily consumption. This
will lead to different capacity of solar panels being ideal for use by these
individuals. One needs to look into their current consumption and their likely
future consumption before choosing to install a particular capacity of solar
panels. Here I will be sharing general guidelines to follow before selecting a
particular solar panel for your needs. Also we will only be focusing on
residential solar panels and not industrial solar rooftops. Also all the
calculations discussed here is for on-grid solar plant.
a. Set your monthly billing amount: Most simplest way to do
this is to average out the monthly electricity bills of last 12 months. It will
give you general idea about your average consumption. Also it will average out,
the higher consumption during summer and lower during winter.
b. Add buffer to this monthly consumption: Once you have
decided your monthly consumption one should add atleast 20% bugger for future
increase in demand before selecting your actual consumption.
Lets take an example to understand
this concept. Lets assume that your bi-monthly electricity bill is 4000 INR.
Number of units consumed will correspondingly be 615 units considering per unit
cost to be 6.5 rupees. Now a 3kw solar rooftop is capable of generating
approximately 13 units per day. Now lets calculate the amount of solar panels
you would require if your bi-monthly consumption is 4000 INR.
Bi-monthly units consumption =
615 units
20% buffer for future rise in load =
615 x 1.2 = 738 units.
Now daily unit consumption = 738/60
= 12.3 units per day.
As we discussed 3kW of solar
rooftops are capable of generating 13 kW of power per day on an average. So for
a person having power consumption of house to be 4000 INR bi-monthly could
easily go for 3kW of solar rooftop and still maintain zero bill every month.
Now lets discuss a general formula which you can use to calculate kW of solar
panels which is right for you.
kW of solar panels = ((((B/C)*1.2)/60)*3)/13)
where B = Bimonthly bill you receive
in INR,
C = Cost per unit of electricity in INR.
Above equation will give you an
idealistic idea about the kW of solar panels which you should choose for your
house requirement.
Choosing the right inverter for
Solar Rooftop
Always choose inverter of more
capacity than the solar panels installed. It will give you flexibility of
increasing the solar panels in future without changing the invertor. So for
someone who is opting for a 3kW solar, they should go for minimum 5kW or 6kW
invertor for future requirements.
Below image will give brief idea about functioning of solar rooftops
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| Source: Indiamart |
On-Grid vs Off-Grid solar plant
1. On-Grid Solar Plant:
This is the one which is directly supplying the power generated by solar plant to the grid. In this case, you are getting the benefit of not paying huge investment for the installation of the battery system. Lets discuss few of the pros and cons of on-grid solar power plant system.
Pros
i. Benefit of using the units of electricity generated even
during night time when there is no availability of solar energy.
ii. You can get paid for the excess units of electricity
produced as compared to what is being used by you.
iii. No worries about availability of power during night time as
everything is connected to grid itself.
iv. Any kind of excess electricity is not wasted if battery is
full like off-grid solar, as it is transferred to the grid directly.
Cons
i.
Returns received
for the excess amounts of units generated against consumed units is very low.
ii.
There is
requirement of installation of 2 separate meter. One for calculating the units
of electricity imported to house and other to calculate units of electricity
exported.
iii.
Solar
plant stops in case of grid power failure.
2. Off-Grid Solar
This kind of solar
plant is not connected to the grid. Hence, whatever solar electricity is
produced in excess gets stored in the battery installed. During day time
whatever excess electricity is produced gets stored in the battery system. This
power can then be utilized when solar power isn’t available. Lets now discuss
its pros and cons.
Pros
i.
Better
return over excess electricity produced as its stored in battery which can be
utilized whenever required.
ii.
Power
availability even during power failure. As power is stored in the battery
system, one can have access to power even during power failure.
Cons
i.
Extra
cost of battery to be bear by you during the installation process. This battery
cost can be substantially high as normally it is lithium batteries.
ii. Excess electricity generated after battery is full will be wasted as one can’t supply the same back to the grid.
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| Off-Grid Solar. Source: Homescape Solar |
Conclusion
As per this discussion,
one can say that the most preferred mode of solar installation depends on one’s
specific needs. But in general most people opt for on-grid solar installation
as it provides benefits in many different forms.