 Hi, this is Vera Cole. I thought it would be helpful if I could give you a quick tour of some of the main features of PVWATS. When you click through from the link in our lesson content, it'll open up this web page. And the first thing you're going to want to do is click through to the calculator. So we're going to click through to the calculator. Now remember, this is a calculator for estimating the amount of electricity a photovoltaic installation is going to produce. So the first thing I want to know is where is your solar installation? For purposes of this demonstration, I'm going to talk first about the system on my property, which is located in Pennsylvania. So the solar installation is in Pennsylvania. And then PVWATS wants you to tell it, what's the closest weather station? This system is located just north of Philadelphia. So let's use the data from the Philadelphia weather station. The next thing the system needs to know is how big is the system? What size of a solar system am I putting in? In this case, this system has 40 modules. And each module is rated at 240 watts. So you'll remember from the lesson that the total wattage is going to be the sum of all of these wattages. So it's going to be 40 times 240, which is going to be 9,600 watts or 9.6 kilowatts for the entire array. So the rating is going to be the DC rating kilowatts. It's going to be 9.6 kilowatts for this system. That's, again, based on 40 modules at 240 watts each. The DC to AC rating factor estimates all the inefficiencies between when the electricity is generated as direct current and when it's available to your home or business in the form of alternating current or AC. In this video, I'm not going to go through all the details of this factor, but I want to point you to some additional information. If you click on Help, and let's open that in another tab. It'll take you to this page. That's spelled wrong. Isn't that crazy? I'm going to have to send them a note, but it's kind of funny when that happens to other people. Anyway, this is a page of excellent information about the parameters underlying this model. It's very easy to read, and it gives good descriptions. So you'll see here, they describe the DC rating. And then this whole next section describes the DC to AC rating factor. And all of the underlying factors and how the calculations work. If you're all interested, I highly recommend you reading or scanning closely this whole section. This page also has information about array types, different kind of rotations. That's tracking systems. This is about the tilt angle of the array, and this is about the azimuth angle, the direction your array is facing. And a few notes about electricity cost. So remember that this page of information is available while you're working with the model. But let's go back to the model. OK, so we're going to leave the default factor here of 0.77. The array type, again, is fixed tilt. We're not doing any tracking, no single or double-axis tracking. The tilt of this particular array is right at 40 degrees. So we'll leave it at 39.9. And it's facing south. And that's the default value, so I'll leave that at 180. And we'll also leave the default value for energy data. So I'm going to just, that's all the input this model needs. And I'm going to press Calculate. Now this table summarizes all of our input data. And this table summarizes all of our output data. So to walk you through this table, first of all, you'll see that their rows are by month. So month one is January. And month 12 is, surprise, December. And then this bottom row are the annual values. This column is solar radiation. Now this is based on historical weather data for the weather station we specified, in this case Philadelphia. So it's saying in the Philadelphia area you can expect to receive this much sun, this much energy from the sun per day. And notice the units of measure. It's energy, so it's kilowatt hours per square meter per day. So in the month of January, our solar electric system is going to receive about 3.3 kilowatt hours per square meter per day. The same system in August is going to get about 5.67 kilowatt hours per square meter per day. The annual value is going to be 4.57 kilowatt hours per square meter per day. And remember, that's for a system meeting all of these parameters. It's located near Philadelphia. It's facing south. It's at a 40-degree tilt. And on an annual basis, it's going, on average, get 4.57 kilowatt hours per square meter per day. That's the energy from the sun. AC energy. This is the electricity the system is going to produce. And this is going to be the final electricity in the form of alternating current that's available for immediate use. In our homes or business, we can even export it to the grid. Again, this is energy. So again, the unit of measure is kilowatt hours. And you'll see that this system can be expected to produce in the month of January about 778 kilowatt hours of electricity. The same system in August is going to produce 1,150 kilowatt hours of electricity. And for the whole year, this system, and remember, this is exactly the system, 9.6 kilowatts with this orientation. And this tilt is going to generate 11,578 kilowatt hours of electricity per year. This is the amount of electricity this system will generate in one year. And this is the dollar value of that electricity based on the default values used by the calculator. Now, what if I were to look at this and say, hm, that's not going to be enough electricity for my house. I need more. What do I do to make more? Well, let's go back to our values. To make more, I'm going to make the DC rating higher. I'm going to say I need a bigger system. So instead of a 9.6 kilowatt system, let's put in a 10 kilowatt system. Now calculate. Well, this changed. Everything else here is the same. And the amount of solar radiation is the same, right? Because the sun hasn't changed any. So all these values are the same. This is the same. But because our system is larger, it's going to generate more. So these values have all gone up. And so we can see that now with a 10 kilowatt system, we're going to generate a little over 12,000 kilowatt hours per year. So that's the relationship. So if I want to make more electricity per year, I need to make my system larger. If I want to make less electricity per year, I'm going to make my system smaller. And that's all for a given location. If everything else stays the same, that's all for a given location, OK? So my 10 kilowatt system is going to produce more electricity than my 9.6 kilowatt system did. So I can keep changing the DC rating and looking at the values of the output to see what size system I need for a particular installation. OK, thanks for your attention. I hope you found this helpful. Please take a play with the model on your own. Take a look at some of the information here. And if you have questions here and all through here, if you have questions, post them to our questions about EGE401 Discussion Forum, I would love to discuss any of this with you more. All right, thank you. Enjoy the assignment.