Capacity Factor?

[Renaissance Man]

Hello! I am new to the forum and just getting started on a DIY residential solar grid-tied system. Before I can begin, I have to fill out the paperwork for a site review from my utility company. One question is the "Capacity Factor" of my system. My system, when built, will be about 15.4KW from the panels and my PVWatts annual production is estimated at 19,241KWh. Can anyone explain the way to calculate the CF?

 

[Madco]

The capacity factor is the ratio of energy generated over a period of time to the energy that would have been generated if the generator were run 24/7 over the same period of time. For solar energy, the CF is usually around 25%

 

[Renaissance Man]

The capacity factor is the ratio of energy generated over a period of time to the energy that would have been generated if the generator were run 24/7 over the same period of time. For solar energy, the CF is usually around 25%

Thank you for your reply. The confusing thing to me is it seems like they are asking me to calculate a number based on a system that isn't even built yet. They know that the CF for solar is well documented at 20-25% so why ask that question? I am just nervous that they will reject my application right off the bat if I give them a wrong answer. I was hoping someone had experienced this before and how they handled it. If no one has, I will just go with 25% and see what happens.

 

[RCinFLA]

Be aware of any homeowner insurance company limits on maximum PV power and peak array voltage. Utility companies may mention it, but I would not solely rely on them telling you.

 

[Madco]

Why are you worried about giving them a wrong number? Just calculate it with whatever PVWatts predicts and you have a defensible result. It will be as correct as anything else (and still be around 25%)! It is really kinda assinine!

 

[Partimewages]

Some utilities only want you to produce about what you will consume.
Is that what this is?

 

[Madco]

No, it is more of an efficiency calculation. Say you have a grid-tied system with no storage, a 10kW inverter, and 10kW of panels. The inverter would generate 87600 kWh if it ran 24/7/365. However, after a year, the system generated 20150 kWh. The capacity factor would be 20150/87600 = 0.23 or 23%.

 

[Madco]

It is really more of a utilization figure of merit that it is efficiency.

 

[OzSolar]

I can see no reason for a utility to ask someone what the (traditional) capacity factor for solar is.

I bet it's more about how much energy usage they are planning to offset with solar. A call to the utility in question is the only way to be sure.

Below is the first chart I found on google for traditional capacity factor.

 

[Renaissance Man]

Hey, thanks for all of the replies! I did call the utility and I think the guy really didn't know and didn't care. Anyway I am going with the PVwatts calculations. I'm pretty sure it's not as big of a deal as I thought it was going to be!

 

[McKravitts]

Hey, thanks for all of the replies! I did call the utility and I think the guy really didn't know and didn't care. Anyway I am going with the PVwatts calculations. I'm pretty sure it's not as big of a deal as I thought it was going to be!

Maybe they were just trying to make it so complicated that you would give up and continue o buy all your electric power from them.