After the site visit, I was sent another preliminary design with
more detail that is shown in Figure 3 and Figure 4. The design
had to be revised because a satellite dish on the roof was no
longer used and two more panels could be added. In addition,
the company had added a few panels to the front roof visible
from the street which my spouse did not appreciate.
After some analysis, it was determined they only added 4%
to the total energy output, so they were deleted. (I later
wondered if the extra panels would have put me over the 10KW
maximum to permit net metering in my state.) All the panels
would be on the back of the house. Since the house is a two-story colonial, they would be not seen from the deck, just in the
back yard some distance from the house.
It should be noted that I had to approve the final design,
even though I had already signed the contract. If the numbers in
the proposal changed because of the site visit or I did not
approve the final design, the deal was off. A project planner was
assigned to us. He was my point of contact for technical issues,
including the status of permits, inspections, and approvals. I
approved the final design.
The array consisted of 38 panels (REC260PE) with a nominal
power output of 260 watts and 16% efficiency. The total array
had a power output of 9,880 watts nominal. The panels have a
10 year product failure warranty, but the lease agreement
guarantees a 20 year replacement life. They are wired in a
series/parallel arrangement, and the DC voltage is fed through
conduit down the side of my house (see Figure 5). You can
barely see the conduit from the ground. It is tucked in the
chimney chase corner.
A close-up is shown in Figure 6 where the feed comes down
from the roof next to an old antenna bracket and old wires. The
wiring is then fed into the basement to the inverter (Figure 7)
and interior shut-off switch (on the right). The inverter is a
SolarEdge inverter (SE10000A-US) rated at 10,000 watts. There
are system shut-offs both inside and outside the house. The
conduit on the left side comes from the array and the conduit
on the right of the inverter goes up to the meters on the outside
of the house (Figure 8). There is a net meter supplied by the
electric utility, a solar performance meter supplied by Sunrun,
and an exterior shut-off.
Microinverters vs. String Inverters vs.
Recently, there has been a lot of discussion on processing
solar power and the best architecture for a solar photovoltaic
system. Here is a short summary of three different methods:
1. Sunrun used power optimizers on my system which had a
small module on each panel to condition the DC before sending
it to the centrally located inverter in my basement, where it is
converted to AC and synchronized to the power line. The only
downside I have found with this arrangement is fan noise. There
40 August 2016
FIGURE 5. Location of feed from the roof.
FIGURE 6. Close-up of feed from the roof.