Solar Panel Installation
These are general guidelines on installing a home solar (PV) system. You must ensure you follow your local bylaws, building codes and electrical codes.
General Steps for a Solar Panel Installation
- Selection of Solar Panels and Inverter
- Layout of Panels on Rooftop
- Installation of Racking
- Installation of Solar Panels
- Fusing, Inverters & Disconnects
Selection of Solar Panels and Inverter
Solar panels come in a variety of physical sizes, power outputs, voltages, etc. You need to match the Inverter to the total output of the solar panels. For our example, we are installing 18 solar panels, each producing 200 watts (3.6kW), with a maximum open circuit voltage of 36.2 volts and maximum output of 7.68 amps. The maximum system voltage for these panels is 600 volts. If we joined all 18 of our solar panels together in a series, we would exceed the 600 volt maximum of the panels. Thus for our installation we are using 2 strings with 9 solar panels connected in series in each string. (maximum open voltage per string = 9 x 36.2v = 325.8v DC). These two strings are connected in parallel for a total voltage of 325.8 DC and maximum amps of 7.68a x 2 = 15.36a.
Our grid-tie inverter is rated for 4kW which will handle the total output from our solar panel array (3.6kW). The maximum input is set at 600vDC and 18 amps. Thus our solar panels will not overpower the inverter.
Layout of Panels on Rooftop
Our rooftop points south and is not shaded during the morning, day or evening. However, our rooftop has a "hip" design - all four sides are angled inwards.
With a hip roof, each row will have fewer solar panels than the row below, as the sides keep moving in - think of a triangle shape.
In our case our solar panels are 65 inches tall and 39 inches wide. Using a tape measure, we located the spot on the ridge of the rooftop, 65 inches up from the rain gutter. We then measured across the roof at this point, to determine the total width we could use for our solar panels. In our case, we found we could install 9 solar panels in the first row.
For the second row, we added one inch to the height of the panels (now 66 inches) in order to leave some room between the rows for expansion. Measuring up 66 inches from the first row and across for the total width, we found we can fit 6 panels into the second row.
Following the same process, we can fit 3 panels in the top row.
Installation of Racking
Our first step in installing the solar panel racking, is to mark the layout. With a chalk-line we first marked the vertical-center of the roof. As it happens, our vertical distance on the roof, is the exact length of 3 solar panels, plus 1 inch of space between each row.
Our solar panels are 65 inches tall. We'll divide this space into 4 parts (65/4 = 16.25 inches) and place the racks such that one rack is 16.25 inches from the top of the panel and another rack is 16.25 inches from the top of the panel. The distance between the racks is 2 x 16.25 inches = 32.5 inches.
As we have the exact vertical length of 3 rows of panels, plus 1 inch of space between the rows, we chalked the first horizontal line at 16.25 inches up from the edge of the roof. If you have more space than required, you could split the difference to leave half of your space at the bottom of the first row and the rest of the free space at the top of the top row.
Our second chalk line, which marks the second rack of the first row of panels, is measured up 32.5 inches from the first chalk line.
We have now marked the first two racks that will hold the first row of solar panels.
For the 3rd chalk line, we measure up 33.5 inches. This leaves a 1 inch gap between the rows to allow for expansion. The fourth row is chalked at 32.5 lines. Row five is at 33.5 inches again - leaving an inch gap between row of panels. The last chalk line is measured up 32.5 inches.
Our solar panels are 38.7 inches wide. Our racks came in 10 foot sections. An end clamp adds just over a half inch to the width. Each mid clamp (between 2 panels) adds another inch. Thus we can fit 3 panels on each 10 foot section of racking. As our setup has 9 panels, 6 panels and 3 panels per row, we don't need to cut any of the racks.
Our racks are installed using a flashing which slides under the existing shingles. Plenty of chalking is applied under the flashing and a hole is drilled through the shingles and into the rafter. Our flashing then has a rubber grommet inserted, more chalking and finally the lag bolt in screwed into the rafter. When installed correctly, there's no concern with leaks.
All racking is installed before we start to install the solar panels on top. We also added a grounding lug to each rack. Every solar panel, plus the racking system, must be grounded. Check with your electrician regarding grounding requirements.
Note: please ensure you follow all safety, building and electrical codes. This info is provided as a guide to installing a solar panel system. Local laws must be followed and we encourage everyone you use a profession installation team.
Installation of Solar Panels
Our solar panels are attached to the racking system with end-clamps and mid-clamps. The solar panels will have a connection box at one end. We installed the solar panels on the racking system to keep all connections at the TOP of each panel. For the first panel in a row, install the end-clamps near the ends of the racks. Our solar panel then sides into place, under these end-clamps. We next added the mid-clamps to the inside of the solar panel and tightened all clamps. Note, we added the ground lug to each solar panel before moving the panel to the rooftop. Each ground lug was added to the same end of the solar panel as where the connection box was located. This keeps all the wiring at one end.
Additional solar panels are added to the row and secured with the mid-clamps.As each additional solar panel is added to the first row, we interconnect each panel. in our case, the positive lead of the existing panel is connected to the negative lead of the next panel. Once the first row had all panels installed, we connected an MC-4 cable from the first panel's negative lead and brought the connection to the other end of the row of panels. We then ran a grounding cable to all of the solar panel grounding lugs and the racking grounding lugs. These 3 connections are run via conduit, down to our combiner box in the garage.
The second and third rows of solar panels where installed in the same manner - install panel, make connections, connect grounding. The positive, negative and grounding wires from the second and third row are connected together to form our second series string of panels. This second string is also brought via conduit, to the combiner box in the garage.
Fusing, Inverters & Disconnects
While we mounted the combiner box, inverter and disconnect switch, we let the electrician make all of the connections. In our case the inverter needed to be mounted on a fire-proof surface such as half inch drywall or cement board.
Each of our two strings of 9 solar panels is connected to a 600 volt DC fuse in the combiner box. These two strings are then jointed in parallel and wired to the DC Disconnect and inverter. The output from the inverter is then wired through a manual disconnect switch and into a new electrical meter. At our location, we have a feed-in tariff that pays us for every kilowatt hour of electricity we produce.
Installing solar panels can be a straight forward job if the time is taken for planning up front. The purpose of this guide is to provide a very general, high-level overview. Before starting any job such as a solar panel installation, know and follow your safety, building and electrical codes and use professional help as required - we used Ontario Solar Farms.