Wednesday, April 5, 2017

Solar

One of our criteria for our house design was to plan for solar panels.  That meant having an unobstructed south facing section of roof.  With an attached hangar, there is no shortage of roof.  It also helps that the south facing roof is in the back, so the neighbors are less likely to be bothered.

Although we always planned to install solar at some point, the "when" was not clear.  For one thing, our finances were a bit stretched when we moved in.  The price of solar panels is dropping steadily, which argued in favor of waiting.  When we moved in, Michigan's rules for net metering were unclear with proposals to replace or change net metering under debate in the legislature.  This spring, a few things fell into place.  The legislature passed new legislation that clarified the rules - somewhat.  Projects completed in the next year are expected to be grandfathered under the current net metering rules for ten years.  Although it is still unclear what the rules will be for future projects, it is pretty certain they will be less favorable.  A little research revealed that solar projects could be financed under a program called Michigan Saves.  We decided to pull the trigger.

Our solar array includes 28 SUNIVA panels.  Each is rated at 280 watts, for a total of 7.84 kW.  The system was installed by Homeland Solar.  The installer sized the system based on our electric bills since we moved in last September.  We reduced the size a bit from their estimate because we really do expect to do better on electric usage in the future.  For aesthetic reasons, we decided to go with the all black panels even though they produce slightly less power per panel than the silver panels.

The first step was to set up scaffolding to safely get up on the roof.  Then, the support rails are attached to the roof.

After the rails are in place, panels are installed.

All 28 panels in place.
DC wires run from the panels on the hangar roof, through the hangar attic and the hangar, into the basement.  The Solar Edge 7.6 kW inverter is installed in the utility room.  Although the inverter is a few feet away from the electrical panel, the AC wiring cannot take the direct route.  The utility requires an exterior shut-off switch near the electric meter.  In most homes, the electric meter is close to the electrical panel, but not in ours.  Fortunately, in anticipation of eventually installing a generator, we had the foresight to install a conduit from the utility room to the end of the house with the meter.  The installers were able to pull three sets of wires through the conduit: one from the inverter to the shutoff switch, one from the shutoff switch to the electrical panel, and one for the eventual natural gas standby generator.


In addition to the electric meter (left) and the gas meter (middle), we now have a solar disconnect switch on the end of the house.
The installed cost came out to $2.55 per watt ($1.79 after the 30% tax credit).  Our monthly payments under the Michigan Saves loan will be a little bit more than the expected reduction in our electric bill, so the project is not quite cash flow positive in the first year.  If electric prices go up, we will be ahead.  In ten years, the loan will be paid off, so we will be saving money even if the net metering terms are not as favorable.

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