Now than ever before in history, people are embracing renewable sources of energy. Among them is solar energy. Fortunately, these systems have been modernized with the capability of storing extra energy.
These solar systems have several components such as solar panels, batteries, inverters, and switchboards, to mention a few. The inverter is nicknamed the brain of the solar system. It converts the direct current from the photovoltaic cells to alternating current consumed by the electric equipment.
Unfortunately, the solar system arrives unassembled, and you have to install it all by yourself or hire a professional. If you are a do-it-yourself person, we will help you install the solar system to your home electricity and install components such as the inverter into the grid.
How to connect solar panels to house wiring?
If you have a rough day connecting solar panels to house wiring, you can take a deep breath. We will explain all in a second.
The solar panel can be installed as an off-grid or on-grid system. What’s the difference between off-grid and on-grid systems?
An off-grid system means that the system is not directly connected to the primary electricity grid. As a result, you will have to purchase a battery to store the energy. While getting the battery, you should ensure its capacity is equivalent to the home’s needs.
On the other hand, the on-grid systems use solar inverters connected to a public electricity grid. Thus, excess power is stored in the utility grid for future consumption. As you can quickly tell, the solar inverters are configured differently in both cases. Let’s discuss them in detail.
On-grid solar system wiring
Storing energy in solar cells results in 30% power loss. Thus, most people prefer the on-grid solar configuration because it does not use batteries. However, these systems use a Grid Tie inverter which requires a slightly sophisticated configuration process. The grid-tie inverter is configured to a solar meter which later connects to the mains.
The meter is used to calculate excess energy from the inverter grid, later stored in a utility grid for future consumption. Also, this type of wiring incorporates a power guide monitoring system that tracks the energy and adjusts the system to ensure that it is performing efficiently. Having understood the on-grid solar system working, let’s look at how to install an on-grid solar system.
Step 1: Get the requirements
Gathering all the needed materials before you start any installation process saves you from time wastage. Besides, it ensures that you will run the process until the end, for you have all you need. Similarly, before you start the wiring process, get the following materials:
- Solar panels
- Grid-Tie inverter
- Ac Wire roll
- Dc Wire roll
- Junction box
- Electric breakers
- Iron L angle
- Conduit pipe
Step 2: Calculating the consumption load
Different homes consume power at different rates. The consumption rate depends on the number of electric equipment and how long they consume power daily. Therefore, calculate the approximate power consumption of your house, then convert it to units where kW is equivalent to 1 unit.
Next, you can calculate the total number of solar panels required in the house, noting that 1kW panels supply four units in a day. Let’s have an example;
Assume that we have a 250w TV in my house that is being used for 2 hours, a geyser that runs for 2 hours, 80W running for 10 hours, and 8 light bulbs rated 18 W. The total power consumption in one day will be equal to the following;
(250 x2) + (1500 x 2) + (80 x 10) + (18 x 8) = 4444watts
We convert the watts to kilowatts to get the total units consumed;
4444/1000= 4.4kW (rounded off)
Now, to get how many solar panels are required in this situation;
1kW solar panels produce 4 units every day, assuming that we have 6 hours of bright sunshine. Consequently, we divide the 4.4 units consumed by the four units supplied by each panel. 4.4 / 4 = 1.1
Step 3: Identify the installation space
Next, you need to calculate h amount of rooftop area you need for the setup. Typically, a single 1kW panel will require 80 to 100 sq. Also, you should remember to leave spaces between the solar panels to facilitate the cleaning process.
Step 4: Design
Most people install the panel facing the south direction to take advantage of the sun’s rising and setting. However, the exact tilting angle varies depending on the latitude and the longitude of the area. However, you should ensure that the installation process is correctly designed for the efficient performance of the system.
Step 5: Connect
At this point, we will be getting our hands dirty. First, install the solar panels on the top of the roof using the J clamps.
Next, we need to connect the panels. Most people prefer the series connection from on-grid panels because it significantly increases the voltage received by the grid inverter. To do that, you should connect the first panel’s positive terminal to the second panel’s negative terminal, which connects to the third panel’s positive terminal and continues the process.
Also, install the switchboard and a switch that receives current from the solar panel.
Step 6: Connect the solar inverter to the mains
Caution! To connect the inverter, you must ensure that the previous is correctly done.
For an on-grid system, you will not be using batteries. Thus, unlike the off-grid systems, you will connect the inverter directly to the grid. Plug it into the main power switchboard to join the grid, which acts as the input wire. The other wire, which acts as the output wire, connects to the switchboard, which supplies the current.
Correspondingly, the inverter receives the direct current from the grid, passes it to the inbuilt transformers, and outputs alternating current to the switchboard, which supplies the current to the various parts of the house.
Step 7: Test
If you have done everything as instructed, you can switch on the mains and observe the inverter, which should be the lighting.
Off-grid solar system wiring
Off-grid solar system configuration is suitable for areas without electricity or places where electricity blackouts are frequent. The inverters of these systems are connected to batteries used to store excess power for future consumption. How do you configure this system?
Step 1: Get the requirements
The equipment needed are;
- Solar panels
- Solar battery
- Interface(e.g. solarcon)
Step 2: Plan the setup
Calculate the total amount of area needed for the installation. It is also advisable that you slightly tilt the panel and face it in the south direction. After identifying the right place to install the solar panel, use the iron L angles to support the panels in the area.
Step 3: Connect the solar panel
Series connection maximizes the amount of power supplied to the inverter. Thus it is the most preferred configuration design. Connect the positive terminal of the first panel to the negative terminal of the next panel, which joins to the positive terminal of the third terminal, and the same behavior continues for the remaining panels.
Step 4: Connect the inverter
In this case, the solar inverter is connected to the batteries. The positive terminal of the inverter connects to the battery’s positive terminal, while the negative terminal of the inverter goes to the battery’s negative terminal. Next, plug the inverter into the grid, which acts as the input.
Solar inverter installation varies depending on the type of configuration. Thus, to connect the grid inverter to the mains, you must choose if it will connect directly to the battery or not. For instance, the on-grid system inverter is connected directly to the mains, while the off-grid inverter output is first connected to a storage battery. Fortunately, we have discussed how to connect the inverter on the two configurations designs and how to connect the grid tie inverter to the mains.
Eng. Matthew Joseph Nandirio is the Founder of walkingsolar.
After graduating from the University of Houston in 2002, matt started working as a Solar Electrical Engineer for several multi-national solar energy companies.
He has a wide range of experiences including solar system requirement analysis, planning, maintaining, debugging and even solar device development through research.
He now shares his 20 years of expertise through his articles on the walkingsolar website.
Further, he is also the author of two books on Solar Technology, “Solar Power for Villages” and “DIY Solar System for Dummies”.