You know about all the good it brings, but how many do you really need?

Like many things, it’s a case-to-case basis. The optimal number of panels varies, depending on the number of people in your home and your usage during both day and night. While there is no definite answer, here’s a general method of how we compute for the optimal number of panels, in three simple steps.

Note: This computation does not take Net Metering into consideration, as the goal is to maximize the use of solar power for your home. Should you wish to zero-out your bill or generate greater savings, a different computation will be used by our solar professionals. Send us your details and we’ll be happy to give you a free quotation.

Step 1 | Determine power used during daytime

The goal is to match your power usage during the day with a system size that’s perfect for it. This essentially prevents any use of power from Meralco whenever there is sunlight. So, the first step to determining the optimal number of panels would be to estimate your daytime consumption.

For example, if you run a 1HP air conditioner (750W), computer (200W), refrigerator (200W), and 5 LED lights (10W each) for a total of 1200W used during the day, consider installing a 1500W (1.5kW) system to offset your usage. On the other hand, if you consume about 2500W during the day, a 3000W (3.0kW) system should be used instead.

For a list of basic household appliances and their estimated energy consumption, click here.

We can also help you determine the system size perfect for your home. Just fill out our form here: Free Quote

Step 2 | Learn the perfect size for your usage

Following the example in Step 1, let’s take (A) 1.5kW and (B) 3.0kW as the total wattage of your solar panels systems. Solterra currently offers 60-cell and 72-cell panels that can support either systems, depending on your home’s specifications. 60-cell panels produce about 275W per panel, while 72-cell panels (slightly taller) produce about 325W per panel.

Given their capacities, a 1.5kW system will require six (6) 60-cell panels or five (5) 72-cell panels. A 3.0kW system, on the other hand, will need eleven (11) 60-cell panels or ten (10) 72-cell panels. Computing for these estimates can be done by simply taking the total system size, divided by the capacity of the panel you wish to use. 

60-cell solar panels produce about 275W

72-cell solar panels produce about 325W

Step 3 | Check how many fit your roof

60-cell panels have a length of 1.6m and width of 1m (1.6 square meters), while 72-cell panels have a length of 2m and width of 1m (2 square meters).

A 3.0kW system with eleven (11) 60-cell panels, for example, would need at least 18 square meters of roof space; while ten (10) 72-cell panels would need at least 20 square meters of roof space. Simply multiply the number of panels with its area in order to find the estimated roof space required for that particular system.

60-cell solar panels occupy 1.6 square meters

72-cell solar panels occupy 2 square meters

As a general rule, we recommend adding 20-30% more space as allowance when calculating the roof space required, as there needs to be free space to move for installation and maintenance access.

Each roof is different.

Prior to installation, we have to consider the shape and dimensions of your roof, proper orientation and tilt, and many more factors. It’s best to consult our solar professionals for recommendation.