Posts Tagged ‘residential power’

Watts up with residential solar power?

Wednesday, March 22nd, 2017

Since the beginning of 2017, the interest in residential solar power systems has grown among homeowners, particularly here in the Rockwall, Texas area. “What do you think about solar?” starts the conversation. Well, the question deserves and answer.

Nothing is free, not the equipment and most certainly not the installation labor. We could start with the energy density factor, but let’s instead start with the practical issue of ownership.

Few homes in my city of Rockwall were built to optimize photovoltaic (PV) solar electrical power. In fact, I should say none of the homes in my city can do so. Why?

Since we recently experienced the vernal equinox on March 20, 2017, it seems appropriate to point to the obvious: sunlight is only available during the day while typical families are away at school solarhouseand work. There is no sunlight to power the PV panels at night. Do you see how this might be a problem?

Let’s look at a home that was constructed to capture the most PV solar power. The roof is a half gable. The pitch of the roof is designed to expose the PV panels throughout the year. Do remember the sun is low in the south during winter, higher in the north during summer.

Next, do you notice the roofing material below the solar panels? The roofing material on the home pictured is not susceptible to hail damage, it won’t rot. Throughout the lifetime of the home, roof replacement is not at all likely. This particular home is in California and the solar power system was provided by Spectrum One Contract Builders. Roof construction of this home is ideal for solar panels.

I invite my Rockwall area residents to walk outside and look at their roofs. Your home may feature hip roof, gabled roof, dormers, and other geometries that don’t allow reasonable exposure to the sun. In most of our neighborhoods, the houses don’t particularly square off with the earth’s lines of latitude or longitude. One Rockwall home with solar panels has a gable roof and the panels are on the east-facing side, not exactly optimal.

The typical Rockwall area roof has composition shingles, a few with wood shingles, and even fewer with aluminum shingles. Before you decide to mount solar panels on your roof, first know there is no existing hail damage. What is the manufacturer’s warranty on the roof? If you mount solar panels on your easily hail-damaged roof, there are probably undesirable outcomes in your future.

For the roofing contractor to replace your hail-damaged roof, those solar panels must come down, then be reinstalled after the roofing contractor drives away. Do you see any roof vents, fireplace chimneys, dormers, gables, etc. that will limit the number and placement of solar panels on your roof?

Have you engaged an engineer to run the numbers? Probably not. Solar salespeople do that, but the motivation for you to buy into a solar program is all about the financial incentives. Right? May I suggest you get an objective report from a registered professional engineer before you sign on the dotted line?

Rockwall requires a building permit from the city and there are new electrical codes in play that affect wiring. You didn’t think about the wiring?

Early PV projects in which I have been involved wired panels in series. Terminal voltage would be as high as 180 volts DC. What happens when a fireman squirts water on a high-voltage electrical system? Yes, he may be electrocuted, so the latest electrical codes require lower voltage which means more wiring which means more cost to you.

Would I ever consider PV solar for my own home? Yes, but later on when more efficient PV panels will be available.

There are more factors to consider before you decide to go ahead with a solar project. The chief thing I hope you take away from my seemingly negative point of view is this. If you want a long-term practical PV solar power system for your home, engage an engineer not associated with the contractor or marketing company that will install it. Ask for a sketch on the layout of the proposed panels. The appearance alone may be the deal breaker for you.

Disclaimer: Rockwall Controls Company, Inc. is not a provider of photovoltaic solar electrical power systems and we rarely provide control systems to residential customers.

John White

Rockwall Controls Company, Inc.
(972) 771-3514