Solar panel dimensions are critical if your roof is small or of an unusual shape. Why? These factors affect the usable area, so whatever you sacrifice in size, you'll need to make up for in efficiency. It may seem confusing, so let's go through the whole decision-making process step by step:
- Begin by calculating your solar panel needs, the solar array output. This is when our solar panel calculator steps in. Alternatively, you can just use the formula:
solar array output = electricity consumption / (365 × solar hours in a day)
where the electricity consumption is yearly and expressed in kWh (our energy conversion calculator can help if your electric meter uses other units). Solar hours in a day depend strongly on your location.
- You need to account for the environmental factor and how much you want to depend on solar power. In other words, how much of your electricity bill you'd like to offset. The equation is:
solar array size = solar array output × (bill offset / environmental factor)
where both bill offset and environmental factors are expressed as percentages.
The environmental factor represents the percentage of energy produced by the solar array and stored without any loss due to humidity, pollution, snow or other environmental conditions.
- The tricky part begins now. You need to estimate your roof area (you might find roofing calculator useful). Exclude the bits you cannot place anything on or are normally in the shade since they won't generate any power. This will give you an idea of the maximum solar panel dimensions.
- There's no one-size-fits-all solution here, and you'll have to research your local options regarding solar panels. You've calculated your solar panel needs, so it's time to check where you can get photovoltaic cells that are the closest to the ideal.
- To see if any of the panels available will fit your roof, you will first need to compute the number of solar panels needed:
required panels = solar array size in kW × 1000 / panel output in watts
Typically, the output is 300 watts, but this may vary, so make sure to double-check!
- The last step is determining the area the potential panels would occupy. The following equation will help you:
area occupied = required panels × panel width × panel length
where both width and length are in meters.
If the area occupied is smaller than your roof area, the system should fit just right!
You can find the number of solar panels you need from the equation:
number of panels = system size / single panel size
where system and single panel sizes are their wattages, not actual dimensions. The system size determines the power you expect from solar panels.
The number of solar panels you need depends on the following factors:
- Your solar panel needs;
- Your usable roof area;
- Solar panel dimensions;
- Photovoltaic cell efficiency.