How many watts will a Suntech STP245-20/Wd produce?
If I am using 33313 of kWhs a year, then how many panels are required?
Comments
To be conservative, allow for 77% of the module's STC rating (245W) for its hourly rate of production once it passes through an inverter, or 189W.
If you are using 33313 kW Hours per year, then you're looking at an average of 2776 kWHrs/month, or 93kWHrs/day. Now you have to know how many hours of sunlight are available for your location: Let's say that's an average of 6 hours per day, for the whole year. This depends on some geographic and local factors. So, 93,000 / 6 Hours of sun per day = 15,500 Watts of required input to offset 100% of your consumption. You would need about 82 modules.
Ghacont,Thanks for your observation - corrected for daily usage. I generally rounded up so the count I get is 82 modules, but now we have a ballpark estimate...
I think there are a lot of factors that go into what a pv system will actually produce.
One way to look at getting to 100% would be to intentionally slightly undersize your project leaving room to add on later. Monitor the system once commisioned for a year or so, and then decide if you have met your goals. If not, simply add the difference required to meet your goals based on the real production numbers from the actual watts installed.
Comments
To be conservative, allow for 77% of the module's STC rating (245W) for its hourly rate of production once it passes through an inverter, or 189W.
If you are using 33313 kW Hours per year, then you're looking at an average of 2776 kWHrs/month, or 93kWHrs/day.Now you have to know how many hours of sunlight are available for your location: Let's say that's an average of 6 hours per day, for the whole year. This depends on some geographic and local factors.
So, 93,000 / 6 Hours of sun per day = 15,500 Watts of required input to offset 100% of your consumption.
You would need about 82 modules.
I disagree with the above comment.
33,313kw/365 days in a year = 91.27kw/per day(daily consumption). or 91270 watts/per day
using the the assumptions above...
91270 watts/per day / 6 hrs average sun per day/ 77% system inefficiencies= 19,755 watts
19,755 watts/245 watt modules = 80 modules
I think the mistake above was not calculating usage down to the day. cheers
I think there are a lot of factors that go into what a pv system will actually produce.
One way to look at getting to 100% would be to intentionally slightly undersize your project leaving room to add on later. Monitor the system once commisioned for a year or so, and then decide if you have met your goals. If not, simply add the difference required to meet your goals based on the real production numbers from the actual watts installed.
Just a humble thought..