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I thought that our 2019 PV system upgrade would be last one, and
it was doing fine in supplying all our electric needs. But, then
we got an EV and installed a home AC charger, and charging the EV
added significantly to our electricity usage. So, we added some
capacity to our solar array to cover this.
I did a fair bit of calculating to estimate the energy needed to
charge the new EV. I estimated the number of trips into town for
a typical week and how many KWH this would take and then added
some for things like coming home from a road trip once in a while
with the battery near empty. This came up to the need to add
about 1300 watts of new PV. I ended up adding 1600 watts to
provide a little margin.
I had 1 row of ten 200 watt panels and a 2nd row (added in 2019)
of twelve 300 watt panels. I decided to leave the row of twelve
300 watt panels alone. On the other row, I changed the ten 200
watt panels to 300 watt panels, and then added two additional 300
watt panels to bring the row up to twelve 300 watt panels. So, I
now have two rows of twelve 300 watt panels for a grand total of
7200 watts of STC power.
The New Panels
Looking around for a good price, I happened on a Signature Solar
ad for Hyundai 300 watt 60 cell panels for $84 per panel (28 cents
per watt). I ordered 12 of these at $84 each with freight
shipping of $150 for a total of $1158 for the panels. Panels
prices have certainly come down a lot since 2009 when I put my
first system in.
The panels arrived undamaged and they appear to be well made. I
have to give Signature Solar good grades on the whole
transaction. They clearly concentrate on low prices, but they
seem to have their system well worked out.
The new panels arriving by freight - well packed on a pallet.
Inverters
My original plan was to use the existing enphase IQ7PD-72
microinverters that were already on the 200 watt panels for the
new 300 watt panels. Since these inverters have a max power
rating of 200 watts, some clipping would have occurred on good sun
days, but when you go through the math it does not have a huge
effect on average daily output. The cost of upgrading to new IQ7+
inverters at about $150 each was more than I wanted to spend.
But, then I found that there were a lot of new Enphase IQ7-60-2US
inverters on ebay for low prices. This inverter is no longer
offered by Enphase, but it was one they offered for 60 cell panels
up to 350 watts, so its a good match to my new Hyundai panels. I
ended up picking up twelve of these for $40 each. Ten for the
upgraded 200 watt panels and two for the two new added panels.
The total for the new inverters with $90 of shipping was $570, or
16 cents per STC watt.
Array Supports
For the ten 200 watt panels that were being upgraded to 300
watts, the upgrade just consisted of unplugging and unbolting the
200 watt panels and placing the new 300 watt panels and plugging
them in and bolting them down. The breaker for this line of
panels was turned off first, and a piece of cardboard was used to
block the sun on the panel being disconnected.
Replacing the 200 watt panels with 300 watt panels.
I have some projects in mind for the old 200 watt panels, or if
the projects don't work out, I will just sell them to someone who
wants to get started in solar at a very low cost.
For two new 300 watt panels, I extended the current panel support
system another 80 inches to the west. This involved putting in
two new concrete footings and a new treated 4 by 4 support
identical to the existing one.
I extended the Ironridge support rails by 80 inches and spliced
them into the end of the existing Ironridge rails.
I bought the Ironridge rail and the additional panel hold down
bolts at our local Platt Electric. This works out well in that
their prices are competitive, and as long as you pick up the order
at their local store, there is no shipping charge, and shipping a
17 ft length of Ironridge rail is expensive.
This brings the total cost to: panels $1158, microinverters $570,
rails and supports $128, misc $50 totaling to $1906, or 53 cents
per STC watt. The federal tax credit will knock off another 28%.
It is amazing how much the cost of solar has dropped since I put
my first array in back in 2009 - it cost me about $4.50 then!
This brings us up to 7200 watts at the STC rating. I believe
that this will cover our house and EV charging needs 100%.
I'll post an update in a year or so to report on how it works
out.
One closing comment is that in the close to 15 years since we put
in solar we have had zero failures of any of the Enphase
components or of any of the PV panels.
Comments
Please leave any comments on the upgrade on the
orginal project page...
Gary
February 9, 2024
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