Frequently Asked Questions

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FAQ's

  1. What is STC, and how does this affect my rebate and cost?
  2. What is a solar photovoltaic (PV) system?
  3. What is a grid-tied solar PV system?
  4. Will a grid-tied solar system work during power outages?
  5. What is two-way (or net) metering?
  6. Will the utility company pay me for the excess electricity I generate?
  7. What is Time-of-Use (TOU) metering?

1. What is STC, and how does this affect my rebate and cost? 

ANSWER: STC stands for Standard Test Condition. The manufacturer’s of solar modules test the modules at 77°F with an artificial sunlight perpendicular to the module. This is how they determine the “sticker wattage”, or what the module says it can produce. For example, the “sticker wattage” of a Sharp ND-216U1F module is 216 watts. Saying this solar module will produce 216W when it is 77°F and the sun is perpendicular to the module. Rebate amounts are based on the STC DC rating of the system.


2. What is a solar photovoltaic (PV) system? 

ANSWER: A photovoltaic (solar electric) system converts the sun’s light energy into electricity by producing direct current (DC) in the PV panels. The DC current is sent to an inverter that converts the DC current to alternating current (AC) for general use in your house or business.

3. What is a grid-tied solar PV system? 

ANSWER: A grid-tied solar PV system’s output is directly linked through your meter to the distribution lines that normally provide you with electricity. The grid effectively “stores” any excess power produced by your PV system and supplements power when your demand for electricity is greater than your on-site solar production. Grid-tied solar PV systems avoid the need for costly, toxic, and high-maintenance battery storage systems.


4. Will a grid-tied solar system work during power outages? 

ANSWER: Due to safety regulations, a grid-tied solar PV system will automatically shut down during power outages. If continued power is essential, you can invest in an uninterruptible power supply (UPS) or generator. Grid-tied systems with battery backup are also available, although they will increase the installation costs, maintenance, and toxicity, while decreasing the performance efficiency of your solar system. Some new inverters will allow use of a single emergency outlet as long as the sun is shining.

5. What is two-way (or net) metering? 

ANSWER: ​In a grid-tied solar PV system, electricity can flow through your meter in either direction, depending on the amount of electricity your system is producing and how much electricity you are using. When your solar PV system is producing more electricity than you need, the surplus is pushed back into the grid, spinning your meter backwards.
At other times, you may need to draw supplemental power from the utility grid, making your meter spin forwards. Net metering keeps track of the difference between the grid-supplied electricity you use and the surplus generated by your solar PV system.


6. Will the utility company pay me for the excess electricity I generate?

ANSWER: APS or SRP will credit future bills for excess electricity created, and will pay the customer at the end of the year for remaining credits at the wholesale rate at that time.


 7. What is Time-of-Use (TOU) metering? 

ANSWER: A TOU rate plan from APS bases the price you pay for electricity on the time of day and the time of year you use energy. With TOU, you typically pay more for electricity during peak hours (9 AM to 9 PM weekdays) or (Noon to 7pm)  in the summer. You pay less during all other hours (off-peak, partial-peak) and in the winter.
TOU can be very beneficial to solar PV owners since, under the net metering laws, the power company must credit you at retail rates for any excess power you produce. So, if you can “sell” your excess electricity at peak rates and buy it back at off-peak rates, your PV system will have a greater impact on lowering your energy costs.