are two fans in the inverter that turn on when
the inverter is converting significant amounts of
power (> 4,000 watts), which is typically in the
middle of the day. If there is a 2% inefficiency,
the inverter has to get rid of 200 watts. The
metal case gets warm on the sides and top.
Would an external heatsink keep the fans from
coming on? I have not tried that because the
two small fans do not make that much noise
and have not really bothered me (yet).
2. String inverters have the panels organized
into groups or strings, and work best with all the
panels on the same plane with no shading. (This
was not my situation.) If one panel in the string
is shaded, the output drops for that string.
3. Microinverters convert the DC to AC
right at the panel before sending the power
down to the basement; there is no need for a
central inverter. They also tolerate shading.
However, microinverters are more costly, and
typically have more components with lower
reliability (e.g., electrolytic capacitors) and lower
efficiency (96% vs. 98% for power optimizers).
Also, the more electronics on your roof, the
higher the temperature swings (and failure rate),
and the more difficult it is to maintain them
when they fail.
There are many white papers (and heated
discussions) on the best inverters and solar
system architecture. They can be easily found
with a Google search of the topic (see
Installation and Operation
From the time I signed the original contract
until turn-on, it took about 4-1/2 months. The
actual time to install the system took less than
two days. Why such a big difference? The rest
of the time was spent by the company
obtaining local permits, scheduling inspections,
discussing issues with the power utility,
answering my questions, revising the design,
For example, the building inspector got into
the act and made sure the brackets that hold
the panels were secured into the rafters of the
house and not just the plywood. Apparently, the
assessors took the opportunity to tour the
property when they heard the building inspector was
It also took two weeks waiting for the electric utility to
swap out my meter for a net meter. It literally took them
10 seconds to do the actual swap. I timed them.
The system went live on August 7, 2015. There are a
few ways I can monitor the performance of my system:
FIGURE 7. Inverter and shut-off (right) in the
FIGURE 8. Metering outside the house.
August 2016 41