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How to Calculate Solar Production.

To calculate how much solar production you could achieve for your property is quit complex as we will explain in more detail below.

If you are looking for a one sentence answer; 

Solar production = Peak Sun Hours multiplied by how many kWp installed – less efficiency losses. 

For the full explanation see below.

Solar Production

The Sun.

Quite obviously, the sun plays a major part in solar energy production. The major considerations when calculating solar production are;  

Intensity – The sun needs to b a certain intensity for the solar panels to generate enough voltage to create electricity. 

Daylight Hours –  In Southern Australia the sun is shining for longer during the summer months and less during the winter months. This will impact solar production. 

Sun Angle – In Southern Australia the sun appears lower in the sky in winter and higher in the sky in summer. This is a major consideration when installing solar panels. It is important to place the panels at the optimum angle to absorb the suns rays throughout the year. Deviation from this angle will impact solar production. 

Temperature

Temperature. 

It’s a commonly held belief that warm places make for better solar production. Unfortunately it’s not entirely true. Solar panels actually lose efficiency in high temperatures and increase efficiency in cooler places. When calculating solar production it is important to understand the average temperature of your location and the temperature coefficient for a particular solar module. (different types of solar modules have different temperature coefficients)

Solar Direction

Panel Direction. 

In the Southern Hemisphere it is the most ideal for solar panels to face towards the north, as this will give the most opportunity for the solar panels to generate electricity throughout the whole day. Whilst it is also possible for solar panels to face east or west this will result in solar production being reduced. East facing panels will make more energy in the morning and less in the afternoon. West facing panels will produce more solar in the afternoon and less in the morning. 

solar pitch angle

Panel Pitch/ Angle.

In addition to the direction that the solar panels face, the angle or pitch is also an important aspect in a solar production calculation. The ideal pitch of your solar array is relative to the longitude of the panel location. 

Shading and Solar Production

Shade. 

The potential of shading is a major concern when calculating solar production. There are different options available to mitigate the loss of solar production from shading, although it is still a significant factor when estimating the benefit of solar. 

Standard string inverter – With a standard string inverter, the impact of shade is significant as shade on 1 panel will reduce  solar production on the whole string. 

Micro Inverters/ Optimisers – By paying extra to use micro inverters or panel optimisers, you can mitigate the effects of shading to only the panels that are being shaded and not a whole string of panels. 

Dirt and Soiling

Dirt / Soiling. 

Dirt and soiling can also be a major factor when calculating solar production. When designing a system and working on an ROI analysis the common allowance is around 3% for dirt and soiling. 

There are ways to mitigate the effects of soiling, such as using micro inverters/ optimisers and/ or regularly cleaning panels. 

Cable losses

Cable Losses. 

The cable that carries DC electricity from the solar panels and the solar inverter can have an impact on solar production. 

As a general rule, the shortest possible distance between the solar panels and inverter is best.  (assuming correct cable size).

Cable losses can also be a factor for AC cables that run from your solar inverter to your electrical circuits. In the same way it is best to have the correct sized cable running the shortest possible distance. 

Easiest way to calculate solar production.

Whilst it is possible to manually calculate potential solar production given almost any situation. Most solar companies now rely on software programs such as Helioscope to calculate a remarkably accurate production figure.

Energy Storage Direct also offers a 100% FREE and No obligation system design and ROI analysis service, so that consumers can make a fully informed decision about the benefits of solar.