Excel Tutorial: Calculate Monthly Solar Energy Output

Name: Solar Power Forecasting in EXCEL Sheet# # एक्सेल शीट में सौर ऊर्जा का पूर्वानुमान
Uploaded: 2026-04-05T08:34:27.205886+00:00
Duration: 15 min 55 s
Channel: Renewable Energy Study Group
Description: Summary and key takeaways on Excel Tutorial: Calculate Monthly Solar Energy Output, covering Project Estimation Basics Solar energy forecasting is required for

Renewable Energy Study Group

Apr 05, 2026

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15 min video

•

2 min read

YouTube video ID: fFVbM6lNsKY

Source: YouTube video by Renewable Energy Study Group — Watch original video

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Solar energy forecasting is required for profit‑loss analysis and investment planning. Manual calculations in Excel enable month‑wise and year‑wise energy yield estimation for projects ranging from 1 kW to 500 MW. Before installing any solar project in terms of kilowatt, the amount of electricity in kilowatt‑hours that the plant will generate must be estimated.

Excel Calculation Framework

Input Parameters

Month and the number of days in each month.
Number of panels (for example, 32 panels for a 10 kW system).
Panel capacity (e.g., 325 Wp).
Global Horizontal Irradiance (GHI) values in kWh/m²/day, obtained from databases such as NREL, Meteonorm, or NASA.

Derating Factors

Soiling losses (e.g., 5 % loss → factor 0.95).
Manufacturing tolerances (e.g., 5 % loss → factor 0.95).
Temperature increase losses (e.g., 5 % loss → factor 0.95).

These factors are multiplied with the rated panel capacity to obtain the effective kilowatt‑peak (kWp) of the array.

Energy Flow Calculations

DC Output – Compute practical panel output, multiply by the number of panels and by the GHI value.
Inverter Input – Apply DC cable loss (3 % → factor 0.97).
AC Output – Apply inverter efficiency (96 % → factor 0.96).
Grid Delivery – Apply AC cable loss (1 % → factor 0.99).

The step‑by‑step formulas are:

Final Power Output (kWp) = (Panel Capacity × Soiling × Manufacturing × Temperature) / 1000
Actual DC Energy (kWh) = Practical Panel Output × Number of Panels × GHI
DC Input at Inverter = Actual DC Energy × 0.97
AC Output from Inverter = DC Input × 0.96
AC Energy to Grid = AC Output × 0.99

Data Visualization

Monthly energy yield is obtained by multiplying daily AC energy delivered by the number of days in the month. Yearly yield is the sum of all monthly values. Plotting the results with 2‑D or 3‑D charts highlights seasonal performance variations, such as lower yields during rainy seasons.

"The ghi value which is following on the site is changing actually side to side and day by day it is changing over here."
"Whenever we are estimating a profit and loss account in the particular when we are doing an investment in a solar sector actually so in that we required what amount of forecasting that we are getting from the solar power plant."

Takeaways

Solar energy forecasting is essential for profit‑loss analysis and investment decisions, and can be performed manually in Excel for projects from 1 kW up to 500 MW.
The Excel model begins with inputs such as month, days per month, panel count, panel capacity, and site‑specific GHI values sourced from NREL, Meteonorm, or NASA.
Derating factors—soiling, manufacturing tolerances, and temperature losses—are applied as multiplicative reductions (e.g., 0.95 each) to convert rated panel capacity into effective kWp.
Energy flow calculations sequentially apply DC cable loss (0.97), inverter efficiency (0.96), and AC cable loss (0.99) to derive daily AC energy delivered to the grid.
Monthly yield equals daily AC energy multiplied by days in the month, and summing all months gives yearly generation; visual charts reveal seasonal patterns such as reduced output during rainy periods.

Frequently Asked Questions

How do derating factors influence the effective panel capacity in the Excel solar model?

Derating factors are multiplied with the rated panel capacity to reflect real‑world reductions. Each factor—soiling (0.95), manufacturing tolerance (0.95), temperature loss (0.95)—is applied sequentially, so effective capacity = Panel Capacity × 0.95 × 0.95 × 0.95, converting watts to kilowatts when divided by 1000.

What formula calculates monthly solar energy yield after accounting for all losses?

Monthly Energy Yield = AC Energy Delivered per Day × Number of Days in Month, where AC Energy Delivered per Day = (Panel Capacity × Soiling × Manufacturing × Temperature / 1000) × Number of Panels × GHI × 0.97 × 0.96 × 0.99. This incorporates DC cable loss, inverter efficiency, and AC cable loss.

Who is Renewable Energy Study Group on YouTube?

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Does this page include the full transcript of the video?

Yes, the full transcript for this video is available on this page. Click 'Show transcript' in the sidebar to read it.

Helpful resources related to this video

If you want to practice or explore the concepts discussed in the video, these commonly used tools may help.

Solar Power Engineering Reference Book Recommended

Provides in-depth technical knowledge on solar system design, efficiency losses, and performance modeling beyond basic spreadsheet calculations.

Amazon →

Solar Irradiance Pyranometer Sensor

A physical tool to measure actual Global Horizontal Irradiance (GHI) on-site, providing more accurate data for energy yield models.

Amazon →

Solar Panel Cleaning Kit

Helps mitigate soiling losses, which the video identifies as a critical derating factor in energy production calculations.

Amazon →

Digital Multimeter For Solar Testing

Essential for verifying the electrical output and efficiency of solar panels and inverters during system commissioning.

Amazon →

Links may be affiliate links. We only include resources that are genuinely relevant to the topic.

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Full Transcript YouTube

hello my dear friends welcome to the
renewable energy study group in the
today's session we're going to see the
calculation of monthly energy generation
in the Excel sheet basically in the
earlier session we have seen the monthly
energy generation in the PV V software
basically the energy generation is
nothing but whenever we are installing a
solar power plant of any size ranging
from the first kilowatt up to the 100 or
the 500 megawatt level of the particular
project so before installing any solar
project in terms of kilowatt we have to
estimate what amount of electricity in
terms of kilowatt hour the solar power
plant will going to get generate because
whenever we are estimating an profit and
loss account in the particular uh when
we are doing a investment in a solar
sector actually so in that we required
what amount of forecasting that we are
getting from the solar power plant there
are basically the two methods when the
manual method of energy generation or
the energy
calculation month-wise also we can
calculate manually with the help of the
Excel sheet and the year wise also we
can calculate over here and whenever we
are calculating the final balance sheet
of the particular Financial balance
sheet so in that cases actually we
required to consider this particular
data over here so basically how we
calculating the monthly energy
generation or the energy yield with the
help of the manual Excel sheet is that
we just prepare a such kind of a format
in the Excel sheet calculation out of
the first table or the First Column is
the month over here that is from January
up to the December month we need to
calculate the particular energy yield
again the number of days in the
particular month we have to select over
here January is carrying 31 number of
days February is carrying 28 number of
days so likewise manually we just
putting over here how many number of
days are there in a particular month
that we are selecting over here
then in the third column we have to
select the number of panel in our
particular solar project so let's say if
you are going for the 10 KOB of a solar
project we required approximately 30 to
32 number of the panels as per the
selection of the utility scale solar
panels actually so we just go for the 10
kilowatt of a solar project so basically
there are number of methods are there to
calculate the number of panels in my
earlier video also you can able to see
for 10 kilowatt of a capacity how many
number of panels we required we were
calculating this number of panel with
the help of a formula then we decide how
many panels will required to connect in
the series combination and how many
strings we required to connect in the
parallel combination in the earlier
videos you'll get this particular
information in the channel over here so
basically we just select the 10 kilowatt
of the solar installation capacity will
required approximately 3 to 32 30 to 32
number of the panels so we select over
here let's say the 32 two number of the
panels will required for 10 Kow of the
solar installation capacity for the
residential scale solar power plant that
we were installing over here so we just
copy this particular 32 number up to the
December month simply you have to just
select this particular corner of the
Cale in the Excel sheet and just pull
this particular Corner up to the
December month that we have been noted
down over here so basically this 32
number of the panel value will directly
getting getting copy over here
again the fourth column is saying that
the panel capacity that we were selling
basically there are number of the solar
manufacturers are there currently in the
market the leading manufacturers like
the Vikram solar Vari solar tataa solar
power plant likewise they have provided
their data sheets for whenever they were
manufacturing the particular solar panel
like there are number of sales are there
like a poly chrystalline monocrystalline
mono standard mono perk bifacial half
cut type of solar cell according to that
their capacity is getting very over here
for this particular case study we're
going to select the 325 data power solar
particular solar panel you can select
any of the solar panel just remember
what is the maximum Peak capacity of the
solar panel is having so let's say if
it's having the 325 wat peak of the
maximum solar panel capacity for the
data power solar module that we were
selecting same module capacity we have
to just copy up to the December month
just select this particular corner of
the select row and up to the December
month just copy this particular value
over
here then in the basically fifth column
we have the average daily ghi value ghi
value called it as a global horizontal
irradiance Global horizontal IR Radiance
in the earlier videos also I have been
explained what do you mean by this ghi
value it has been the combination of
direct normal ear radiation and the
direct horizontal IR radiation that is
falling normal solar IR radiation
horizontal diffuse solar irradiation the
combination becomes the ghi value which
is global horizontal irradiance there
are number of website through which you
can calculate what is the global
horizontal air Radiance value for any of
the site that you are calculating the or
installing the solar project so let's
say this data is for the Mumbai region
District so we can calculate this value
either from NRL website rather we can
calculate this value from Mom website
rather we can give this value from the
particular NASA database over here this
we can get from the Google also just
copy this particular value write a
particular District name and for the
district name find out these values in
the Google and just put this value from
the December to uh January to the
December month every month in the
particular location the ghi value which
is following on the site is changing
actually side to side and day by day it
is changing over here just note down
this value over here for the subsequent
calculations over here
so basically Tak an average of it so
average we get 5.87 kilowatt hour per M
Square per day the unit of ghi is
kilowatt hour per M Square per day
according to that we could do the
subsequent calculation in the Excel
sheet over here next thing is the final
power output of a solar moduel basically
the final power output of a solar module
is what after considering the number of
dting factors because whatever the model
manufacturer is giving us that is 325
wat Peak that is the main capacity of
the solar panel but actually when we say
in the Practical environment there is a
increase in the temperature is having
there are the soiling losses are having
there are the P losses are having light
induced degradation losses are having
cabling losses are having much of the
losses are having actually so we have to
consider the particular daating factor
which actually more affecting over the
panel capacity then we can estimate 325
wat peak of a solar panel will generate
practical cases this much amount of the
power over
here so what we just over here like say
the equal to we just write whenever we
are writing the formula in the Excel
sheet we need to write start with the
equal to then the bracket we choose the
panel capacity which is the 325 W Peak
multiplied by we have to choose
basically the daating factor the first
Factor we choose as the soiling Factor
if any soiling is depositing over the
solar panel let's say the 5% losses are
happening over there so we take 95%
efficiency which comes 0.95
multiplication Factor 0.95 resembles to
5% loss of the particular due to the
soiling losses so 0.95 just multiply by
daating Factor multipied by we take here
manufacturing tolerances manufacturing
tolerances consider of L losses P losses
in the particular solar cell so we take
5% of the manufacturing tolerance loss
which resembles to
0.95% of dting factor also we are
multiplying by the temperature
increasing Factor as the temperature
goes beyond 25° Centigrade per degree
increase in the temperature there has
been the decrease of the power output up
to some percentage module to module wise
this temperature coefficient value is
getting increasing or the particular
changing over here so whenever we select
a data sheet of a module or a solar
panel in the data sheet it has been
mentioned over there so so basically
approximate we take 5% of the
temperature losses over here so we just
multiply by 0.95 and we just complete
this bracket over here divided by 1,000
so we'll get the value in terms of the
kilowatt Peak over here so we are
getting over here
0.28 kilowatt so this much basically the
final power output we are getting after
considering the derating losses due to
the manufacturing tolerances soiling
losses and the temperature D rating
Factor over here so just copy with this
value up to the December month simply
put over the row and just copy this
value up to December month over here in
the seventh column it is written that
actual DC energy output from the solar
array it means that if we are combining
32 number of the solar panel what will
be the output in terms of kilowatt hour
the solar array is giving actually at
the DC side so we can calculate this by
this formula equal to in a bra we can
take what is the output we are getting
from Individual solar panel in the
Practical situation multiplied by what
will be the number of solar panel we are
choosing in the array so we select the
particular cell multiplied by what is
the basic ghi value that is horizontal
Global horizontal IR Radiance value of
the particular site over here so what we
have done final power output again the
ghi value multiplication and the number
of panel multiplication and so we get
56.8 Kow hour is the actual DC energy
output from the solar array so we just
particularly just pull this value up to
the December month so we came to know in
the month of July the value is
37.4 in the month of January it is 56.8
actually it is because in the global
horizontal IR Radiance value which we
are getting from solar radiation in July
which is typically a rainy season in
India actually so that is why the solar
radiations are lesser and thus it is
reflecting the actual DC energy output
that we are getting from the solar array
over here then we're going to proceed
for DC input at the inverter so when we
are giving the power from the combiner
box up to the inverter we were using the
DC cable over here considering that
there is a 3% losses are there due to
the DC cable so we just write this
formula equal to in a bracket actual DC
energy output from solar array in terms
of kilowatt hour multiplied by we just
multiply by
0.97 which is the dting factor resembles
to 3% losses due to the DC cable and
enter so here we can calculate up to the
December amount we just pull this value
subsequently changes has been happening
per particular month to month basis over
here we're going to on the ninth of the
colum actually it says that AC output
energy from the inverter so whenever we
are giv the power to the inverter from
the DC to AC conversion losses has been
happening over here so we can say the we
can consider over here the inverter
efficiency which resembles to the DC to
AC conversion losses so equal to in a
bracket DC input that we are giving to
the inverter in terms of kilowatt hour
multipied by what is the efficiency of
inverter just see the data sheet of
inverter that you are choosing according
to that most of the inverter is having
96% of efficiency so we multiply by 0.96
which resembles to 96% of efficiency of
inverter that we were selecting for
residential scale solar project and
enter so from this you can calculate up
to December month just pull this value
on the road side subsequently changes
has been happening in the month to month
wise over here 10th column we see the AC
energy delivered to the grid actually so
whenever the energy is passing from the
inverter from inverter up to to the
particular metering panel or the
switching panel actually customer
switching panel we were using the AC
cable which is AC armor cable we are
using and we were considering that there
is 1% losses will be happening for the
AC cable you can change these losses
according to the site and what cable
that you are selecting for the
subsequent application so in this case
study we select 1% AC cable losses so
the AC output energy from the inverter
in terms of kilowatt hour multiplied by
0 .99 where 0.99 resembles to 99%
efficiency or the 1% loss is due to the
AC cable and enter subsequently we
select this particular column and just
we pull up to the December month and
simultaneous changes has been happening
per individual month according to this
ghi value and last column 12th column we
see monthly AC energy yield it means
that month-wise how much amount of unit
our 10 Kow solar power plant will
generate at actually so this we can
calculate up to equal to in a
bracket what AC energy we are delivering
per day actually so it is 51.79 for
January month so we select this
particular sale multiplied by how many
number of days are there in the
particular month so the January carrying
31 February carrying 32 select the
particular sale actually and say enter
so it says that
1,654 this much kilowatt hour has been
generated in the January month
subsequently just pull this particular
sale up to December month and you came
to know what is the monthly energy
generation has been there for the
month-wise analysis over here and lastly
we just write sum of all these parameter
over here so we just write the formula
what is the yearly energy yield is
getting generated so use the command of
sum command equal to sum in a
bracket so basically equal to sum in a
bracket and we just copy this particular
sale up to December month and bracket
complete over here enter so we get
17572 181 kilow hour per year of units
has been generated by the 10 kilowatt
capacity of the solar project if you
want to do a graphical analysis of it
just select this particular column that
is monthly from January to December and
just go on insert and make a select the
graph that is a 2d graph 3D graph
whatever the graph you've been
comfortable so I'm choosing over 2D
graph over here so it will come over
here that is from one month that is
January month up to the December month
how the energy yield variation will be
there for the 10 kilowatt of the solar
project just click on this any one of a
column right click on it add data levels
over here so we came to know in the
January month we are creating 1,65 units
March month we are creating 1,8 1 37
units subsequently there is a July
August September which is a rainy season
in India the energy yield will be lesser
again in the winter season energy yield
will be higher over here so likewise we
can analyze month-wise energy Generation
by the solar power plant with the help
of the Excel
sheet fine thank you for the watching
the video