solar electric system

Posted June 15, 2009 By admin

solar electric system
what would make a solar system add energy to an electric bill instead of replace it?

we installed a pv solar system for a customer, but his meter is speeding up instead of running backwards like all the other systems. what could cause this?

Hey Jared, frustrating problem you have there isn’t it? Let’s narrow the field a bit. I assume you have an array of some size connected to a grid tie inverter. There are two possibilities here. One, your system is actually pulling power in from the grid when it should be going out. Two, the meter installed on the house is a newer type, which in some cases looks like the old electric-mechanical ones we grew up with, but differs in how the logic inside works. Here is a simple test you can do. Go to the house at a time when you have good midday sun. Have the homeowner turn off all nonessential loads. This will put your system in a state where it should be producing enough power to feed the home and the grid simultaneously. Now examine the meter and see which direction and how fast it is spinning. It should be spinning in a direction that indicates power feeding out to the grid. You won’t know which way is which yet, but you will in a minute. Next, have someone turn off the inverter, so that you know no power is feeding back onto the grid, and examine the meter while this is done. If the meter spins faster, but in the same direction, all is well, it means the home was using more power than the array was providing, but deactivating it increased the amount of grid power the house needed to keep running. In this case I would suspect the home has some unknown load someplace, such as an attic fan running continuously, or a well pump with a bad check valve, and so forth. If the meter slows down when you turn off the solar, than it means one of two things. First, that your solar system is actually drawing a load someplace. Without seeing the system you installed I couldn’t begin to guess where the problem might be. I would suspect the inverter or AC wiring from the inverter to the house. Second, that the meter on the house is a new type that only runs in one direction, and it sees the extra power from the grid as more load power.

The third thing that could happen is the meter reverses direction when the solar is turned off. This indicates that the system is working well also, but the homeowner simply is using additional power someplace after hours.

As a side note, after doing this test by turning the inverter on and off, try also turning off the AC feed from the house to the inverter while it is running and see if the results are the same. If you get a different result, it might indicate that the solar array is in fine shape, but the AC wiring to the inverter or the inverter itself are suspect.

I’m wondering, you said, “We” installed this array, are you a solar installer for a living? If so you might put in a call to the inverter manufacturers tech support and throw this at them, if problems like this have occured before with their product, they usually know about it.

Good luck Jared, and take care, Rudydoo

Clean Energy News: Buying a Solar Electric System