Special Bd. of Aldermen — 08/06/2019 Page 8
The other thing that we consider as far as our design goes is long term longevity and usability of that building so
you will see on the Transit Garage, it is kind of a funny shaped array. Well we want to make sure that this
system is going to be operational for 30 plus years. In that time frame all of those little boxes there, those are
HVAC units, air conditioners, compressors, they are going to need to be replaced, they are going to need to be
maintained, they are going to need to be accessed. So we want to make sure in our designs to account for that
so future City maintenance, totally outside of the project, outside of the solar project is not negatively impacted.
So that is the reasoning for the kind of broken up array there.
Mr. Weeks And just for your interest before moving to the next building, we do have on this overview slide the
percent offset of these facilities, you see load offset the right most column and for that Public Works Garage that
projected output, power output amounts to about 70% of the power consumption. | can speak in more detail to
Alderman O’Brien’s question about net metering. But in brief, that is a fairly ideal arrangement where all of the
power will be used behind the meter sort to speak on an annual basis, with a little bit of surplus power generated
during the peak summer months, less than what is consumed obviously during the lowest production winter
months. But you will be getting the equivalent of full value for nearly 100% of the power because as a “small
customer generator’ a system below 100 kilowatts AC, that’s the AC inverter rating, | can differentiate a little
more detail if you’d like. But as a defined small customer generator, the net metering statute provides for the
ability to use that power anytime within a monthly billing cycle; meaning a peak summer day like today where
you overproduce, will provide power that you use next week when it is raining within the same billing cycle or at
night when the HVAC and the lights may be on. So we can elaborate in more detail if you would like but being
at close to but below 100% is really an ideal place to be in terms of the value of solar electricity and both of
these facilities are 70 and 81% a nice place to be. James, the Fire Station?
Mr. Hasselbeck Sure so this was the second project that we identified that would provide the greatest economic
and environmental value to the City on the Lake Street Fire Station. So it is a beautiful building and here we are
looking at a more conventional pitched roof. So here again it is a metal standing seam roof, so if you are
familiar they are metal plates with these kinds of little seams that are visible. Those are our favorite kind of roofs
to work on in New Hampshire for two reasons. One, they last forever so there’s no issues about roof longevity
and two, we are also not penetrating these metal roofs. We work with a couple different manufacturers who
design and supply these types of clamps and they clamp directly onto the seams themselves. So instead of
penetrating through the roof membrane and into the structural surface of the building, we are clamping on to
those seams to give us the structural integrity we need to support the solar array.
Here, because we are not relying on concrete blocks, the dead load is significantly less. So these systems we
are only adding anywhere between 2 to 3 pounds per square foot. Even so, we still run through the same type
of professional engineering analysis to confirm the structural suitability of the building. So this is a very straight
forward install again, the big concerns that we always get is “what is going on with my roof warranty”. We are
going to be able to maintain that, we are going to be able to utilize a variety of different roof surfaces; you see
we are not putting solar panels on the northern side of things focusing on the most productive sections of the
roof and it is fairly straight forward from our perspective, these are very simple installations.
Mr. Weeks And | would note again that 126.8 KW that is the DC the panel rating. That is each of the 409
panels times their wattage of 310 watts. That is again, the DC rating, the AC rating, we have capped
strategically at 100 kilowatts to retain that small customer generator classification which increases the value of
every kilowatt hour that we export.
Mr. Hasselbeck | think that that’s a really excellent point. Solar frankly is quite complicated. We are trying to
balance economics, we are trying to balance environmental goals and we are trying to balance often rapidly
changing State and Federal Policy.
