How to fine-tune your power supply

Installing a solar system is only part of the process – once everything is up and running, you need to fine tune your mix of solar, battery and utility to get the best out off your investment.

Optimising your load begins with understanding your load profile and this can be discovered through your system’s monitoring app. At its most basic, a monitoring app will show the energy consumption, solar production, battery production and import from the grid. The aim is to maximise solar production while reducing importation from the grid. This can be done by shifting loads to times of high solar production such as 10am to 4pm. Not all loads can be shifted, however, some loads are perfect to run during the day and can be managed with timers – such as pool pumps, geysers, borehole pumps and any other load that can be set to run at a time of your choosing. Even loads that are not able to be shifted can be powered by battery after dark if you have sufficient solar power to charge the battery during the day.

In Figure 1 below you can see that there is a heavy load running between 19:30 and 21:30 – this is being powered by utility thus not gaining any benefit from free solar power. On investigation it was discovered that the geyser was responsible. This is an example of an appliance that can be shifted to run during day light hours, as it will keep the water hot for a long time after it has run.

Figure 1. Unbalanced consumption/production

In Figure 2 we have shifted the geyser to run from 11:00 to 15:00 – we did this by adjusting the timer – timers are key in being able to load shift. The geyser is now entirely powered by solar power and thus heating the water is now completely free. A similar exercise can be done with pool pumps and any device that can run during the day.

Further analysis of the graph in Figure 2 shows that the system ran on battery until about 1 AM, it then switched to utility. When the sun came up at 6:45 it started charging the battery until just before 11AM – as the battery is now full the inverter stops using the utility and powers the loads by a combination of solar and battery power. As long as the load does not exceed the combined capacity of battery and solar it will continue to be powered until the battery reaches about 50% (cut off voltage, which is adjustable) – the system then reconnects the utility. This cycle continues every day.

Figure 2. Optimised Consumption/Production

This system has now been optimised to take advantage of low cost solar and battery energy. This maximises the return on investment and reduces the utility bill.

Be smart with your solar instillation, you only save if you understand how it works!