Going Solar - Installation

Part IV - Installation day arrives!

After a few delays over the Christmas period and waiting for the panels to be back in stock, installation day finally arrived. The solar company (Space Solar) has its own installers. A van and a pickup truck (piled high with solar panels) pulled up that morning. The crew placed ladders and clambered onto the roof and inspected it for an hour or so. The chief technician then gave me the news. It was going to be hard to place all the cells. He did not see any value in putting cells on the south facing roof (as was in the original design). Instead, he suggested squeezing it into a spot which is under the eaves and be in shadow till about 1 PM. He reckoned it was better than putting it on the south facing roof. He also offered to install fewer panels than the original layout and save a bit of cost but I was not for it. On the whole, I think it was an improvement on the original design.

The original design had a few panels on a south facing roof and was a bit optimistic about some of the panel placements.

The roof itself was not in tiptop condition – I should have had it inspected by a roof guy before covering it up with panels. Fortunately, I had some drone footage of the roof before the panels were installed. I had to sign a waiver with the installer to take responsibility for any roof related problems down the road.

The installation of the electrical panels was the first step while the roof was being readied for the cells. Two boxes were put in in addition to the main box. The first housed the Enphase Envoy-S Metered and the other a safety switch that is supposed to trip if anything untoward happens.

Solar Panels

The solar panels used are LG Neon2 (LG335N1C-A5) rated at 335W.

They come with a 25 year warranty. They are roughly 1.7x1.0m in size. They have 6x10 individual cells with an output of about 34V and 10A. The module efficiency is 19.6%. There are 32 of them, putting out a theoretical 10.72 KW.

Micro-inverters

Due to panels pointing in different directions, my setup uses micro-inverters – specifically the Enphase IQ7+. It is rated at 290W – a little lower than the panel. This means my 10.7 KW array is actually a 9.3 KW array. This is common practice when a single inverter hooks up to multiple panels - inverters are underrated as panels seldom operate at their peak power - but I can't see why this is done for micro-inverters.

Each solar panel has two outputs – the positive and negative. This plugs into the IQ7+.

The IQ7+ units are daisy chained. With so many panels it makes sense to spread it across the three phases. Interestingly, neighbouring panels are alternated between the phases rather than connecting a set of clustered panels to the same phase. The outputs of the inverters are then piped to the electricity panel. They first go to the protection switch and then to the mains.

Q Relay

This unit sits between the solar array including the inverters and the mains supply. This is the Enphase Q-RELAY-3P-INT. If anything goes wrong, this relay trips, isolating the solar array from the mains. The problems can be under or over voltage, under or over frequency or presence of DC current. If and when the error condition goes away, it connects the array back to the grid. This is the 3 phase version and isolates all three phases and the neutral. It talks to the Envoy and lets it monitor the status of this relay or remotely upgrade the software.

Envoy-S Metered

This is the part I was particularly interested in and it deserves its own blog post.