With the increasing popularity and the availability of green energy products, most energy modelers will inevitably find themselves with the need to model photovoltaics. In order to model photovoltaics in EQUEST, a user must go to the utility and economics module. Once there, a user can create a photovoltaic module by right clicking on the said folder, or right clicking on the project name, and selecting “create photovoltaic module.” While you can select the photovoltaic type, I would recommend loading a component from the library. EQUEST only has one default entry, but that will suffice for now. So we select okay, and here we have the Sun Soaker 250. This has pretty standard variables for a photovoltaic module. Please note the height and width-- it's approximately 6 by 4 feet, or looking at the bottom, an area of 26.1 feet squared. If we can simply select these parameters, and please note that EQUEST allows the user to get very specific, including entering some advanced alga-rhythms. For now we'll select this as a module and click done.

At this point, it seems that we have modeled our photovoltaic, however, we haven't told it how many solar panels we have, nor have we told it which meter or rate to apply this to. So, we also need to add an electric generator, which gives EQUEST the means to transport the photovoltaic energy. Once we add the generator, we have to select a type as a photovoltaic array. Once we click okay, we're going to be prompted to enter a number of factors, which you would be required to know as EQUEST does not design the photovoltaic system. However, if we enter the capacity, in this case let's say it's 120 kilowatts with the minimum tracking of 60 volts and a maximum tracking of 400 volts, now we select the photovoltaic module that we just created, and the mount type which basically states if the particular panels are shading the building, or they're off to the side, in this case we're going to set them as standalone and click done. We also have to specify the number of inverters. In this case, we'll say that there are 50 inverters. The mount tilt, or the angle that these panels are at, is going to be 40 degrees, which are facing south by default. Now having those parameters, EQUEST automatically fills out the rest of the variables in the electric generator. If we look at the photovoltaic array, EQUEST put 7 modules and series based on our voltage and capacity requirements. You can see our capacity, as well as our number of inverters which is also listed. It's important to get the number of series modules and the number of parallel modules correct, as EQUEST will calculate the voltage and the amps from these two numbers. Let's not forget to add the number of parallel modules. In this case let's say we have 200 parallel and 99 of them series. This is just to make sure we ramp up our capacity. Here we'll click done.

There's still some additional steps required. We have to go to the electric meter and specify co-generation. In this case it's set to “don't run,” which means our generator won't run at all and essentially, we've turned off our panels. In most cases now-a-days, a user may sell the electricity back to the utility company and therefore photovoltaics are typically run at maximum. However, if selling the electricity was not an option we may not want to over run our panels and therefore we would want to track the electric load. In this case we're going to select “run at maximum.” Finally, it's important to note, and if you forgot to do this it would be okay because it's a default value, but it's important to note that the utility rate has a buy/sell mode and isn't just buy only. At this point we can calculate our stimulation. We have to save the changes. When the file runs, we can view our output and looking at our monthly utility bills, since we have a very large amount of solar panels, we see that in the summer months (or the sunny months) we note that we're actually getting paid. Our total cost annually has decreased quite significantly, in fact, it's been cut in half. Now you know how to add photovoltaic arrays, but please note that we could have gotten creative and created additional electric meters as well as other rates, and sold the electricity directly. Since there are so many options, it is for the user to decide how to apply them all. But these general principles will allow you to model photovoltaic arrays. Remember, you must create a module for the photovoltaic, a generator, and finally, you must specify that the electric meter allows co-generation. Typically we want to run it at the maximum for photovoltaic arrays.