2024 Upgrading Our Solar PV System One Last Time :)

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.


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.


Please leave any comments on the upgrade on the orginal project page...


February 9, 2024