Going Solar: What You Should Know Author:

Understanding your current utility costs and the extent that solar will affect those costs is very important in making the decision to switch to solar. It is also important to understand how solar PV systems work, and what factors can affect your production levels. So, let’s go over it!

First, let’s break down your utility bill and the fees you are currently paying. Your bill can be simple or complex, depending on your utility company and amount of energy you use, but either way it might require a little explanation.

Service Charge: Essentially a flat monthly fee for doing business with the utility. It can be as small as $1 for residential, and is a bit larger for commercial. Going solar will not change this cost.  

Generation Charge: This is the actual cost of the electricity that is used each month. That electricity can come from multiple entities using various methods for generation including: nuclear, coal, oil, etc. The cost is charged in increments of kilowatt-hours, or kWh, and can range from $0.06/kWh to $0.40/kWh. Going solar will change this usage and overall cost.

Delivery Charge: Also known as Delivery Service Charge, this is the charge to transport the electricity to your home/business including lines, poles, transformers, and substations. This fee can vary greatly, and is also charged in kWh increments. Solar will change the usage and overall cost.

Demand Charge: This is a charge for when you use electricity the most, based on the period of time detailed in your rate plan. This charge is often misunderstood; it is used to analyze the maximum amount of wattage that a home/business needs at any one time during the month. This ensures that the location would have enough energy at it’s peak demand.This charge varies greatly between locations. Solar might affect this number, but it’s generally considered a charge that will not change with solar.

Arizona: APS just rolled out a new demand charge plan that would make it much less affordable for Arizonans to go solar.

If you switch to solar before July 1, 2017 you will be”grandfathered-in” to current net-metering and demand charge rates. Time is of the essence!

On-Peak & Off-Peak Generation: Also referred to as “Time-of-use billing,” these charges vary on the amount of electricity you used throughout the month during on-peak and off-peak hours. These on-peak/off-peak hours vary based on your utility and location, but primarily off peak hours are 7pm-noon and on-peak hours are noon-7pm. In Arizona, On-peak hours can reach their most expensive rate usually 3-6pm weekdays during June-August. A solar array, especially with a battery backup system, can work well to alleviate these charges.

If you have more questions, most utility companies will have a page defining all the terms and charges you will see on your bill.

In Arizona: APSSRP

In San Diego Area: SDG&E

Solar Energy Diagram: How Solar Works

When understanding Solar PV Systems, there are several variables that can affect the system, but hardware-wise it primarily comes down to three parts: the solar panels, the inverters, and the racking.

Solar Panels: The panels are the primary component to any solar system, and also the most expensive. Solar panels are rated by the amount of DC (direct current) they produce under standard test conditions. Their rating is used to represent the panel’s predicted power production under ideal sunlight and weather conditions. Using their rating you can compare basic production numbers between panels; for example, a 320-watt panel will produce more energy than a 280-watt panel. Most of the time, the higher the energy efficiency, the costlier the panel. Higher cost in panels will affect your PPA, financing and overall return on investment so do your research or ask your Rooftop Solar representative for recommendations on panel sizes specific to your needs.

Inverters: Inverters convert the DC (direct current) power from your solar panels into AC (alternating current) power for the grid. The two types of inverters commonly used include central inverters and microinverters. Central inverters are wired to multiple panels, while microinverters are wired to individual panels and convert electricity at the panel. To learn more about the differences and pros/cons of each type of inverter, especially in hotter climates, read this blog post.

Racking: Racking refers to the mounting that secures the panels – usually rails, although there are rail-less systems as well.

It is somewhat tricky to predict production estimates, because there are many components that can influence your power production. The three main factors taken into account when estimating your production levels include shading, azimuth, and pitch.

Shading: Shading can come from trees, adjacent roofs, or other obstacles around your home. We use specialized shading tools, similar to Project Sunroof (where you can see your roof’s solar potential yourself), to analyze the amount of shade your roof receives throughout the day/year. Shading varies throughout the year because of the angle of the sun changing with the seasons (The sun is lower in the winter, leading obstacles to create more shade than when it is shining high in the summer.)

If there are too many trees in the way, we may suggest cutting or trimming them before we start your solar installation.  We will do the cutting for you, but never without discussing it  first, and getting consent to do so.

Azimuth [az-uh-muh th]: Solar Azimuth determines the angles to place panels so that they are facing the direction that the sun is shining from. Azimuth is just as important as shading, because it dictates how much sun will be shining on the panel throughout the year. Solar panels are the most efficient when they are on the south-facing roofs.

Pitch: Pitch, or tilt, refers to the actual angle of the solar panels. It is the least important of the three, but it does still affect production.


This post was influenced by Green Tech Media’s original blog post “What Customer’s Need to Know Before Going Solar.

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