What are the advantages of creating an account?
Registered users can record their site values, and so don't need to enter their longitude and latitude every time. They can also create new solar panels, in case one of the existing ones doesn't match.
Why do you ask about latitude and longitude anyway?
Because the expected power output depends on the cosine of Φ, the incidence angle of the array to the sun. We can calculate the position of the sun from the current time, but in order to calculate the value of Φ we need to know exactly where the array is, and what direction it's facing.
What is the Sandia model and where does it come from?
What do you mean by site efficiency?
This is a combined term for all the various losses inherent in converting DC to AC. This can vary considerably from site to site. The best explanation we've found of all the various factors involved can be found here.
How do I create a new photovoltaic site?
Only registered users can create a site. Record the new site values by clicking Record instead of Submit on the Solar form page.
The database doesn't have an entry for my type of solar panel, should I do?
For a rough approximation, just pick the closest panel to yours and use that. However, for a best results you should create an account and add your solar panel to the database.
How can I enter a new solar panel into the database?
Only registered users can create new solar panels. Many solar panels are nearly the same. For example, the Mitsubishi PV-MF 185 TD4 is very much like the Mitsubishi PV-MF 180 TD4. Go to the Solar panels page, find the closest solar panel and click on the [copy] link. You will be able to update values for any solar panel you entered.
I'm entering a new solar panel, but it seems the datasheet doesn't specify the active area. What do should I do?
Sometimes the manufacturers provide the details of the dimensions of each cell. If so, it's simply a matter of multiplying by the number of cells. Measuring the cells will also work, but please remember the area should be specified in square centimeters. If all else fails, you can leave the entry blank, and the server will calculate an estimate of 89% of the total surface area.
Where did you get your solar panel information?
Most of it actually came from specifications we found on Certified Modules.
The model's prediction doesn't match my measured values. What should I do?
Please tell us about it. We want to make the model as accurate as possible, and are working to improve it every day.
What is the advantage of using this site instead of PVwatts?
The biggest problem with PVwatts is that you have to fuss with it for half an hour before it will make any predictions. Our site is designed to produce useful information very quickly.
Are there any other good sun position calculaters?
My question isn't on this list. How can I get an answer?
Please send us your question, we'll do our best to answer it. Please note that although the email address is optional, of course we'll need it if you want a reply.