solar panel max energy output per year

[hamsuplo]

so say im looking at a system that has 28kWp. i multiply 28000W by the number of seconds year in a year to get joules, then divide by 3600 to convert to kWh which is
246144.022 kWh
so that is my max theoretical output.

now the actual yearly output of the system im looking at is 29,474.95 kWh, which is 0.12% of my theoretical, which means that yearly, on average i am only getting 2.88 hours of daylight that powers the solar panel (0.12*24 hours per day)

does my math seem correct?

[Sunking]

so say im looking at a system that has 28kWp. i multiply 28000W by the number of seconds year in a year to get joules, then divide by 3600 to convert to kWh which is
246144.022 kWh
so that is my max theoretical output.

now the actual yearly output of the system im looking at is 29,474.95 kWh, which is 0.12% of my theoretical, which means that yearly, on average i am only getting 2.88 hours of daylight that powers the solar panel (0.12*24 hours per day)

does my math seem correct?

Not even close to being right. For a grid tied system you fist have to find out what you daily average Insolation is for your area with the tilt and orientation it is to be installed in. USA average is 4.4 Hours. Next system efficiency is about 77%. So for 1 day production is 28 Kw x 4.4 Hours x .77 = 94.8 Kwh/day. Multiply by 365 to get a year.

[hamsuplo]

Not even close to being right. For a grid tied system you fist have to find out what you daily average Insolation is for your area with the tilt and orientation it is to be installed in. USA average is 4.4 Hours. Next system efficiency is about 77%. So for 1 day production is 28 Kw x 4.4 Hours x .77 = 94.8 Kwh/day. Multiply by 365 to get a year.

thanks. can i get a source for the 77%? thanks again

how can i find the daily average insolation? im in toronto, ontario, canada

[Naptown]

thanks. can i get a source for the 77%? thanks again

how can i find the daily average insolation? im in toronto, ontario, canada

PV Watts there is a link on the home page.
That rating is for the standard derate factors. You will have to tweak them if you are using modules with a + only power tolerance or microinverters etc etc. But is a good place to start from

[hamsuplo]

PV Watts there is a link on the home page.
That rating is for the standard derate factors. You will have to tweak them if you are using modules with a + only power tolerance or microinverters etc etc. But is a good place to start from

yup, i got it. do you know how i can find the daily average insolation? i assume that the 4.4hours that sunking gave accounts only for the maximum sunlight per day because i found online that everywhere in the world has 12 hours of daylight per day on average. do you know how i can calculate the 4.4 hours that sunking calculated?

thanks in advance

[Naptown]

yup, i got it. do you know how i can find the daily average insolation? i assume that the 4.4hours that sunking gave accounts only for the maximum sunlight per day because i found online that everywhere in the world has 12 hours of daylight per day on average. do you know how i can calculate the 4.4 hours that sunking calculated?

thanks in advance

you use the 4.4 hours x array watts x derate x 365 = system output

The 4.4 hours accounts for cloudy days rainy days etc. There is also not enough useable light early and late in the day.
The 4.4 is the energy that strikes the array / 1000 W per square meter.

[hamsuplo]

you use the 4.4 hours x array watts x derate x 365 = system output

The 4.4 hours accounts for cloudy days rainy days etc. There is also not enough useable light early and late in the day.
The 4.4 is the energy that strikes the array / 1000 W per square meter.

yup, i understand that. but how can i find that value for my area? im in toronto ontario. is there a website for a list of values for different areas?

thanks in advance

[Naptown]

PV Watts there is a link on the home page.
That rating is for the standard derate factors. You will have to tweak them if you are using modules with a + only power tolerance or microinverters etc etc. But is a good place to start from

yup, i understand that. but how can i find that value for my area? im in toronto ontario. is there a website for a list of values for different areas?

thanks in advance

Uh where I told you in a previous post
In red above

[hamsuplo]

Uh where I told you in a previous post
In red above

i found the derate factor from it; can u perhaps guide me to where i can find the number of hours thing? thanks

[Naptown]

Variable I II III IV V VI VII VIII IX X XI XII
[SIZE=4][COLOR="#FF0000"]Insolation, kWh/m

[hamsuplo]

[QUOTE=Naptown;44039]Variable I II III IV V VI VII VIII IX X XI XII
[SIZE=4][COLOR="#FF0000"]Insolation, kWh/m

[Naptown]

i saw that, but that data has units of kWh/m^2/day. i was looking for the average daily sunlight in units of hours

Those are the numbers to calculate solar output from a PV array.
I have no idea why you want to find the average sunlight time in hours. I guess it would be 12. Most of which are useless for solar production. Only the hours listed above will work to calculate output and are an average on the watts available per day on average for the month.

[hamsuplo]

Those are the numbers to calculate solar output from a PV array.
I have no idea why you want to find the average sunlight time in hours. I guess it would be 12. Most of which are useless for solar production. Only the hours listed above will work to calculate output and are an average on the watts available per day on average for the month.

to calculate the derate factor from sunkings quote

"Not even close to being right. For a grid tied system you fist have to find out what you daily average Insolation is for your area with the tilt and orientation it is to be installed in. USA average is 4.4 Hours. Next system efficiency is about 77%. So for 1 day production is 28 Kw x 4.4 Hours x .77 = 94.8 Kwh/day. Multiply by 365 to get a year."

i need the Wp of the arrays (28kW) * 0.77 (system efficiency.)* 4.4 hours (number of hours at which daylight is maximum, to account for shady days etc) which will give me units of power (kWh). i dont know how i can use the solar insolation (units of kWh/m^2/day) to help find the maximum potential solar energy generated in a year

[Naptown]

to calculate the derate factor from sunkings quote

"Not even close to being right. For a grid tied system you fist have to find out what you daily average Insolation is for your area with the tilt and orientation it is to be installed in. USA average is 4.4 Hours. Next system efficiency is about 77%. So for 1 day production is 28 Kw x 4.4 Hours x .77 = 94.8 Kwh/day. Multiply by 365 to get a year."

i need the Wp of the arrays (28kW) * 0.77 (system efficiency.)* 4.4 hours (number of hours at which daylight is maximum, to account for shady days etc) which will give me units of power (kWh). i dont know how i can use the solar insolation (units of kWh/m^2/day) to help find the maximum potential solar energy generated in a year

Last time here is the formula
STC wattage of all panels X derate factor (use .77) x Average insolation in KWH per Sq meter per day from the chart I gave
X 365 days = annual output of array.

Example
10 KW of panels x .77 x 4.4 (or whatever the average is you need to do this yourself) X 365
so based on an insolation of 4.4 hours per day average
10000 x .77=7700 x4.4 =33880 x 365=1233770 Watt hours per year or 1233 KWH per year

[russ]

Average sunlight hours in this manner is just the average insolation in watts divided by 1000 or an annual average insolation of 5.07 kW/m2/day would mean 5.07 sunlight hours.

A term some consider useful and I consider to just be confusing.