During normal conditions, a grid-tied solar PV system “pushes” electricity into the
home’s electrical service to be used by electrical loads. Excess energy goes through
the meter to the electrical utility. During grid outages, a home backup generator starts
itself and “tells” the transfer switch goes into action. The transfer switch isolates the
generator from the grid, protecting linemen and not causing electrical interference on
the grid.

Utilizing both systems, the home is saving money during normal operation and powered
up during electrical outages. However, there are some issues that need to be
addressed for this setup to work safely and correctly.

Grid-tied PV systems are basically current pumps. They sense the grid’s electrical
parameters and dutifully push electricity into the circuit. The word “push” is used
because in a sense, that’s exactly what it’s doing – it’s generating electricity with more
electromotive force than the grid’s supply. Wait, what?

Imagine a water pipe supplying a house with 40 psi. Say the house wanted to send
water BACK to the supply. It would have to generate MORE pressure to send the water
back against a 40-psi supply. So, it might generate 45 psi so that the water flows
backwards.

This fundamental concept applies to any electrical system that has both a generator and
a PV system. A PV system cannot distinguish between a grid or a generator. During a
power outage, the PV system will attempt to back feed a connected generator, thinking
that it’s the grid. This can cause damage to the generator and possibly fires or electrical
hazards. Careful consideration must be taken to isolate the solar system from the
generator.

There are two ways to accomplish this: One method is to connect the PV output circuit
to the utility side of the generator’s transfer switch. This ensures that when the grid
electricity is not available, the PV system doesn’t have a place to export, and shuts off.
The other method is to install a contactor on the PV output circuit. Basically, the
contactor (a large switch) shuts off the connection to the PV system when the
generator is running. Generac Smart Management Modules can be configured to
perform this task on Generac units.

These two simple isolation techniques can ensure that your two electrical generation
devices don’t cause thousands of dollars in damage to each other, the home, or its
occupants.

On March 1 st , 2022, Pedernales Electric Coop announced a change to its Solar Interconnection
Rate. The change was made after results of a board-commissioned study were published in
November 2021. The stated mission of A Review of the Value of Solar Study, performed by GDS
Associates and corroborated by the Perryman group, for Pedernales Electric Cooperative was to
“true up” the previous solar interconnection rate; to account for a “subsidy” that PEC claimed
solar owners were receiving at the expense of non-solar owners.

This subsidy is described in the report as follows: “The “Value of Solar Study” shows that a
member-owned solar system provides some decrease in costs for transmission access charges
during the summer, but solar systems do not reduce the direct costs incurred by PEC for
investment, operations, and maintenance of the distribution system.”

“With increasing use of distributed generation among customers, electricity providers must
determine the appropriate method and amount of compensation to provide these customers. The
compensation must be fair and equitable to all customers. In addition, it must cover associated
costs to make the programs economically feasible and sustainable.” – Perryman Group
Meters at solar-equipped services record Delivered power, Received power, and Net usage.
Previously, PEC billed solar owners for the Net kilowatt hour value. Bear in mind that a solar
system’s electrical production services the home first, with excess power traveling “up” the
meter and onto PEC’s lines. Essentially, PEC was buying each kilowatt hour received from the
member at the delivery rate.

“From a rate standpoint, the reduced energy purchases of a member with [Distributed
Generation] will be treated the same for equity purposes as if a homeowner installed energy
efficiency measures to reduce energy consumption.” -Value of Solar Study, 2021
A kilowatt sent back to PEC’s lines is credited on the member’s bill at a rate of $.055377 per
kilowatt hour. Essentially, members will pay for every kilowatt delivered at the normal rate, but
see a line-item credit on their bill for about 5.5 cents per kilowatt hour sent to PEC’s electrical
infrastructure.

For members considering going solar, this will affect their ability to accurately calculate
financial payback models, as a produced kilowatt hour may be worth about 5.5 cents or about
twice that if consumed. One strategy might be to orient arrays westward, to closely match power
demand curves. Calculating solar production is easy, matching consumption in real time can be
challenging.

Value of Solar Study: https://www.pec.coop/wp-content/uploads/2021/11/Interconnected-
Generation-Value-of-Solar-Study-Report.pdf
Perryman Group Review https://www.pec.coop/wp-content/uploads/2021/11/Interconnected-
Generation-Perryman-Group-VOSS-Review.pdf
PEC Interconnection Rates https://www.pec.coop/your-service/distributed-
generation/interconnection-rates/

Once again, the good people of Wimberley were challenged by an unruly meteorological event.
The name is still being debated – “#Icenado’23”, “Elmmageddon”, “Oaknarök”, “The
Snappening”. But as chainsaws wail their sad dirges to fallen trees, the community’s response is
as expected – helpful, neighborly, compassionate. At the time of writing, First Baptist Church
(FBC) has a new mountain of wood chips rising in its street front. The forum is full of kind folks
offering to help and warnings of rip-off artists. And at home, everybody is hard at work clearing
their yards, cleaning out their fridges, and probably sipping a drink and shedding a tear at the
trunk of their favorite old live oak.

Five days after the front blew in, there are over 1000 electrical meters out of service – a large
portion of them in the Wimberley area. As the area has grown and developed, PEC has
expanded service to new neighborhoods and communities. Many of these developments draw
power from a distribution system that stretches over large ranches with limited access,
overgrown easements, and canyons, hills and valleys. For our heroic linemen, the struggle is
real. For our folks without power, the deep-freeze is a biohazard.

As one might expect, demand for generators is surpassed only by chainsaw purchases. Since
Snowpocalypse’21, the community has seen a steady growth in home back-up installations. For
genset owners, the play paid back dividends. For the community, the play also worked out,
benefitting homes and community fixtures alike. FBC is implementing plans to install a large
diesel generator and work with first responders for such outages. For homeowners, their
generators provided opportunities to help themselves as well as others:
With the lights and heat on, there are opportunities to grab some lumber and shore up a
favorite tree, invite the neighbors over for a movie and a hot meal. Not that close to your
neighbor? -Send a batch of chili over (beans, no beans – judgement-free zone). With the hose
bibs steadily dripping, there is time to go check on the elderly and kiddos, let the linemen into
the neighbor’s gate, run a bale of hay out to cold livestock, knock the ice out of the troughs.
Maybe just get some work done to avoid lost wages. Plan to create your own opportunities.
“In preparing for battle, I have always found that plans are useless, but planning is
indispensable.”
-Dwight D. Eisenhower

Home backup generators may have been considered a niche market a few short years ago, but
as our community continues to jump power hurdles such as epic storms with mass power
outages, global pandemics, war in a critical location for energy production and transfer, and
finally rolling brownouts due to excessive heat and growing grid demand – it would seem the
generator market is here to stay.

With the mad rush to find these elusive generators comes a new set of challenges. Should I
purchase one myself or go through a dealer? Do I call the gas company or an electrician or
both? Can I install it myself? Perhaps most importantly, what happens if something goes wrong
with my new system?

The first step is finding a technician on a manufacturer’s website. These are contractors that
have been trained by the manufacturer to service their units and exercise warranties. For
example, Generac, the most popular home backup brand, has several certifications, such as Air-
cooled and Liquid-cooled technician. If anyone else calls the technical support line including a
system owner, electrician, gas company, handyman, or gifted brother-in-law – they will be
referred to a technician on the company’s website. Put simply, unless the caller can quickly
recite their “Technician ID number”, warranties or tech support issues are not supported or
resolved. This is true of virtually all backup generator manufacturers.

In addition to warranties, scheduled maintenance is required for most generators. To use a
Generac example again, after 25 hours of run time on an air-cooled unit, a maintenance service
is required. This involves an oil change, filters and setting the valve lash on the engine to a
specific tolerance. So, if the system runs for even a single day, a Generac trained technician
needs to put their skills to work on that machine after its “break-in” period so that it’s ready for
the next outage.

Finally, Generac technicians carry a factory-issued parts kit for onsite repairs. These include the
“usual suspects”, required to repair either an air-cooled or liquid-cooled model. As the reader
might guess, they’re only available to Generac-trained technicians. They also carry technical
manuals with all the technical specifications necessary for repairs and have direct phone access
to tech support.

For current or future owners of backup generators, it’s certainly worth a quick search and a
phone call to find a local technician trained on your model and brand.

With 2021 ending with a collective sigh, we look to ’22 with hope that the new year brings a
sentiment of “we got through it!”, not “hold my beer”. To be on the safe side, many residents in
our valley continue to invest in emergency power options – primarily generators. There are a
few key considerations to installing a whole house generator.

Backing up a whole house will involve an electrical service rebuild. For example, a 200 amp
service will likely consist of a 200 amp meter socket, 200 amp main panel, with one or more sub
panels. For the entire house to be backed up, the whole 200 amps must be wired through a
transfer switch. A transfer switch takes power from either the grid or the generator – never
both, always separate. There is no other code-compliant way to tie a generator into a home.
Furthermore, if the service is rated for 200 amps, the transfer switch must be rated for 200
amps.

There are two main classes of whole house generators: air-cooled and liquid cooled. Air-cooled
models use engines like what you might find on a UTV or a commercial zero-turn mower. They
come in a small, unobtrusive housing that isn’t going to compel the HOA president to… “get
excited”. Maximum output is about 24kW, which is 100 amps – usually plenty to run an entire
house, and run on liquid propane or natural gas. The liquid-cooled models are substantially
larger, housing an in-line, four-cylinder engine with a radiator – much like you’d find in a small
import car. These units start at about 20kW and run up to 60kW and can run on LP, NG or
diesel. They are ideal for large estates, with multiple buildings and other significant loads, such
as pools, large well houses, detached living spaces, etc. While the smaller units are available
with a few weeks lead time, the large units are 32+ weeks out.

A good strategy for a home nearing the limit of an air-cooled unit is to employ management
modules. These load shedding devices are installed on one or more large loads, such as an
HVAC furnace, and serve to protect the generator if it approaches overload. It achieves this by
temporarily shutting down its respective load if it senses the generator is reaching redline.
Thus, the heat shuts off for about 5 minutes to keep the generator for shutting everything off.