Sunshine Design Engineering Services
RF test engineer Joe Cahak, owner of Sunshine Design Engineering Services, recently
had a photovoltaic panel system installed on his southern California home. After
much research and running through return on investment (RoI) calculations, he made
the decision to invest in a state-of-the-art system by Semper Solaris in San Diego.
If you have not looked into modern PV technology, you might be surprised - as was
I - to learn that rather than all the panels feeding their DC outputs into a common
AC inverter that handles phasing issues with the street service, instead each panel
has its own inverter and phase matching circuit so everything simply feeds into
a 2-pole circuit breaker. Doing so eliminates single point failures and allows graceful
degradation if necessary rather than taking down the entire system. Joe has provided
a very nicely done write-up on the system and its installation.
See list of all of Joe's articles at bottom of page.
Solace in Solar
Figure 1 - Solar World Panel
Figure 2 - Solar Panel Grid and Corner
Figure 3 - Solar Panel Rear Electric Connection
By Joseph L. Cahak
Copyright 2013 Sunshine Design Engineering Services
I consider myself a conservative investor and also a practical environmentalist.
I have watched alternative energy and especially solar for many years and closely
looked at the technology, the lifetime, the efficiency and the economics of various
incarnations of solar systems. I also looked at methane and wind power as possibilities.
None quite fit the bill as easy and low maintenance, until now.
I finally made the decision to purchase a system after many years of looking.
We decided to go with a company called Semper Solaris in San Diego, CA. They serve
the entire Southern California area. So why did I purchase a solar system now and
what did I get? Why did I go with the vendor I did?
In order for me to give a bit of perspective on the solar topic, please bear
with a quasi-historical review. In the early days it was 12 or 48VDC lead acid batteries
and single inverters and high DC losses between the solar cells and the batteries.
The batteries were expensive, heavy, dangerous and prone to failure with regular
replacement costs. The systems were OK for small scale and/or emergency use, but
not cost effective for total home power systems. The solar panel glazing and solar
cells did not hold up well in the sun. The solar cells also suffered high temperature
power output loss. The DC line losses are very prohibitive as is the battery losses
Another reason working against the solar system cost and maintenance was the
competing lower cost of the grid. In California the cost of power was already very
high. The last few years we have had power deregulation and other stupid politics
and energy gaming schemes with the big energy and power companies colluding to set
high prices. The rates are due to go up a minimum of 6-8% per year for many years
to come. In addition, recently Edison Electric and SDG&E decided to shut down
San Onofrae nuclear reactor. They are working to try to make us rate payers pay
for the failed generator. So rates will really jump. Estimates range from 30-40%
in addition to the 6-8%/ year projected increases. This makes solar very attractive
for southern California and Arizona. In addition the minimum electric price is $5
per month and SDG&E is expected to raise it to either $10/month or $50/month.
We are waiting to find out. Reviewing my SDG&E bill I see they now charge me
$65 for electric generation, $3.48 DWR bond charge, $65.81 distribution and $1.88
Competition Transition Charge. I find it interesting that they want so much more
for distribution. These charges sound excessive to me.
Where we live in central San Diego County it gets very hot in the summer and
Air Conditioning is critical. We minimize it as much as we can, but with tiered
rates, we pay a minimum of $0.17/KWh. We can pay of $0.35/KWh when using more than
597 KWh. This coincides with the high heat of summer. This adds up to steep costs
very quickly. Now the AC will run the most while we produce the most solar power
mid day summer. The panels are have an aspect ratio sized for maximum output when
the heat load on the house is highest through the spring, summer and fall. In addition
the tax incentives for Solar power are lapsing after Dec. 31st this year. Even with
this loss on credit, solar will still be a viable electric rate investment given
the increases coming.
The Solar Cells in the early years were only about 6-8% efficient at best and
they did not hold up well under heat and intense sun. The contacts also did not
always adhere well. They also were prone to corrosion around the contacts. The newer
solar cells are larger, have good heat resistance and lifetime. The single crystal
cells have higher efficiency than the cheap poly-silicon cells so prevalent in the
market today. The efficiency of our panels is 14.8%. The implant and surface finish
holds up to the heat and sun better than previously and has a highly rated lifetime
warranty. They also have better grids and interconnects for longer life. Solar World
encapsulates the cells and contacts in a moisture proof hermetic seal.
Many solar panels are not built well and can have the glazing cloud and crack
after time; some of them get moisture inside easily and fail to shed it well to
keep the panels working best. Some panels are not built to last for the long haul.
The Solar Panels we got are from Solar World. They are US made and of the highest
quality and have a 25 year warranty. They are solidly built of all aluminum frame
and solid corners. The panels are clear covered with a moisture and environmental
seal and backed with a white solar resistant material and then the glazing sits
on the panels to help with heat transfer and lower reflective loss, all very lightweight
and strong. I was told I could stand on the panels even in the center.
A few years ago, Enphase Energy developed what is now known as the micro inverter.
The Micro Inverters have changed the alternate energy market completely. With the
micro inverters, the DC from the solar panel is converted in small inverters at
the solar panel to AC for feed into the home AC entry panel. All that was needed
was some Quad20Amp breakers to the 240/208 VAC AC feed panel.
Figure 4 - Enphase Micro Inverter Top
Figure 5 - Enphase Micro Inverter Bottom
Figure 6 - Quad Pak Panel Breaker
Figure 7 - Electric Panel Labeling
The solar system uses Enphase Micro Inverters model M215 and has one inverter
for each panel. This has several advantages. Each panel puts out it individual maximum
output to the inverter which converts to 240V AC and is synchronously feed back
into the utility grid. This gives the lowest line losses to the AC Line Power. Batteries
are no longer used, as the power grid becomes the backup system. You are merely
adding power back and getting credit up to the amount of electricity you use over
the year above what you produced. You typically will not make money from the utility
in California. The power companies have strong agreements and regulations in their
favor. So the strategy is to make enough power to almost cover your maximum average
total power. Our system should produce > 95% of or Electric use today. One final
feature of the micro inverters is that if one or more panels lose some or all power
due to shade, the loss only affects the shaded panels. All other panels will still
produce all that they can or not. The synchronous inverter detects the frequency
and phase of the grid electric feed and synchronously inverts and steps up the VDC
input to the 240VAC output to match the line characteristics and the added phase
needed to produce instead of use power.
The Enphase units each report to an Envoy Communications Gateway. We log in through
a web portal and can monitor our panels' output, status and contact support when
The Solar power feeds into most 200 AMP home panels. They just feed in thru breakers.
This saves a huge amount on panel replacement.
When the installation crew worked the roof for the installation mounts, they
discovered a bit of roof damage and the old roofing paper was dried to powder. So
we had to add about $2400 for a section of roof repair. They fixed two leaks in
the process. We weren't thrilled about the added cost, but expected it.
Final System looks great and has a low profile that is not visible from the front
of the house.
Figure 8 - Complete Solar Installation
Figure 9 - Side View with Gap Above Roof Tiles
Figure 10 - Solar Panel Close-Up
Figure 11 - Solar Panels After Tree Trimming
We have talked to and looked at many of the solar systems and finance agreements
over the years, but just never saw one that had all I was looking for. Then I gave
a call to Semper Solaris after seeing an ad in the paper. Semper Solaris is a local
company and one of the founders was a marine. We met Mike, one of the salesmen and
he explained the system and I liked all the features and warranty. The finance terms
are all fine for many people in different income situations. I was just getting
back to work, but had some saving to invest in the right things. So I asked about
cash discount and got an 8% savings on the total for paying with cash. This investment
of $21K would "earn" me about $170-300 a month for the next 25 years. Sounds like
a good retirement investment to me. Certainly better return than I was getting for
One note on leased solar system is that is may impact your ability to sell or
the sale-ability of your home. Some of the leases and systems may not be attractive
to prospective buyers and it may greatly limit your range of buyers.
20 panels rated at 245 watts each for a total full power ~3.5-5kWh for about
600-1000kWh/month or an annual average of 740kWh/month. The panels have a rated
module efficiency of 14.8%.
We are using about 742kWh/month annual average presently. Our house is about
1800 Sq Ft and we live in central San Diego County. So our highest cost utilities
are the water well pump, the freezer, refrigerator and the Air Conditioner/Furnace.
The solar system was estimated generate about >96% of our total electric usage.
As I write this, on a sunny November day, 6 weeks from solar minimum, we are
getting 26 kWh/Day from the system. With some quick estimates for the solar min
and max output, one can approximate of 20-35 kWh/day for a monthly output range
of 600-1000 kWh. At this day's output of 26KWh, if we had a full 30 days of sun,
would equate to 770 kWh/month output. This output in fall at the beginning of November
sun season is a very good sign to start with. We'll be watching to see how things
stack up when the days get cloudy as well to see the impact to the overall total
collected. The overage also accommodates the cloudy days to keep the average at
better than 700kWh/month.
The roof has an aspect angle of 30 degrees. The sun ranges here in San Diego
County between 33.5 and 80.5 degrees. So a 30 slope means it is perpendicular to
a 60 degree sun. This puts sun max collected in the spring (~April 15th) and fall
(~Sept 15th). Our hottest days are in July-October so the aspect is well suited
I gave them a cleaning after 3 weeks. We have horses and live
in a dry, windy and dusty area, so they build up dust in the dew laden mornings.
I used some light dish soap and a half cup of white vinegar to cut mineral deposits
with city water. I found a great 16 ft variable length rod and brush/squeegee and
wide bucket to the cleaning and wiping dry. Home Depot had pretty good deals on
them. I saw about a 200-300 Watt bump in power output after the cleaning.
The total system cost was $21,200 after 8% off for cash discount with $2400 roof
repair and $6500 tax credits yields $17,100 net cost
Return on Investment
Notes on Permits
- The ROI for 17,100 at today's electric rate is $2500 for a payback period of
- The ROI for 17,100 at next year's rate is $3500 for a payback period of 4.8
- The earning after the system is paid off is $3500 per year. So the income from
the loss offset is between 14.8 to 20.5% annually or about $208-$290/month. Not
too bad an investment.
- Not to be forgotten is the property value increase with an owned system on the
house. I figure the house value could have increased by at least $30K.
- San Diego County Building Permit was obtained after the system was drafted and
- San Diego County then performed an on-site inspection to approve the building
- SDG&E Permit To Operate - for solar power hook up and right to operate
We give Semper Solaris a 5 star rating. They were professional in the sales and
explanations of the deals and system. Mike was real upfront about everything and
provided me with follow up materials to share with this article. I was told the
serve the entire Southern California area: San Diego, Temecula and Murrieta.
If this interests you, call them and ask for Mike Barnett, tell them Joe sent you.
Mike has given me his word of special deals for all referrals.
CA licensed General Building Contractor: #B978152
1637 Tierra Montanosa
Alpine, CA 91901
Sunshine Design Engineering Services
is located in the sunny San Vicente Valley near San Diego, CA, gateway to the mountains
and skies. Are you looking for new things to design, program or create and need
assistance? I offer design services with specialties in electronic hardware, CAD
and software engineering, and 25 years of experience with Test Engineering services
in RF/microwave, transceiver and semiconductor parametric test, test application
program development, automation programs, database programming, graphics and analysis,
and mathematical algorithms.
- RF Connectors and Cables
- Searching for the Q
- Hybrid Heaven
- Noise and Noise Measurements
- Solace in Solar
Semiconductor Device Input Parameters with Vector Analysis
- Computing with Scattering Parameters
- Measurements with Scattering
- Ponderings on Power Measurements
- Scattered Thoughts on
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23517 Carmena Rd
Ramona, CA 92065
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Posted November 5, 2013