5 Ways to Improve Solar Self Consumption

When it comes to installing a solar power system, solar self consumption is the name of the game these days. With Victoria adjusting its Feed in Tariff (FIT) to 6.2 cents/kWh on January 1st there’s not a lot of incentive to export your freshly harvested sunshine energy back into the grid, just so your electricity retailer can mark it up and sell it to your neighbour. From an economic point of view, it’s much better to consume that sun power on site and offset the cost of you having to purchase electricity from the grid at 25-30+ cents/kWh.

If you are a home or business consuming electricity during daylight hours and can self-consume all the solar energy spilling off your roof, it’s great, you can get good value from a solar power system and you might pay your system off in 4-5 years. If not you may be exposed to exporting a larger portion of your solar electricity at a low rate, pushing out your payback period.

There are a few things that you can do to increase solar self consumption from your solar power system. They range from no-cost behavioral change to energy management options and more expensive battery storage solutions. Here’s five ways you can improve your financial return on your solar system by optimising self-consumption from your rooftop.

  1. Change the times when you use electricity

The no-cost way to maximise consumption of your solar energy generation is to change the times that you use appliances. If you are able to modify your electricity consumption patterns so that you are consuming more electricity during the middle of the day when the sun is shining, you will help to minimise your solar export. Offsetting at 30c/kWh is better than exporting at 6c/kWh. Remember this is not an exact science and it won’t work for all households or all appliances, but if you can turn your dishwasher on at lunchtime, do the washing during the middle of the day or turn the air conditioner on when the sun’s out, it will be beneficial towards the financial savings you’ll get from your solar system. What I always say to our customers is “don’t turn your life upside down for your solar system, just be aware of how it operates and take advantage of it where you can”.

  1. Use a timer

Installing a timer can be a good low cost way to co-ordinate appliances to come on during daylight hours. Obviously it won’t work for all appliances, but pool or spa pumps, water pumps, and in some cases even heaters or hot water systems can be put on a timer so that their time of operation coincides with solar production. Some appliances like dishwashers and washing machines will even have a built in timer that will allow you to program when they come on. Again this isn’t the perfect solution, because if it is overcast and your solar system isn’t producing a lot of power and your pool pump is running, you will be purchasing the excess power from the grid probably at peak rate. But if your pool pump was running on peak rate anyway, it’s going to be better to have it more closely matching with solar generation times. If an appliance was running on an off-peak rate there’s probably a deeper analysis required.

  1. Solar inverter with energy management relay

Some inverters are now incorporating smart energy management functions in them that allow for optimised solar self consumption of your solar energy. Austrian inverter manufacturer, Fronius is one company that has been leading the charge here. They have integrated an energy management relay into their new range of inverters the Fronius Glavo and Fronius Symo.

Fronius Galvo Solar inverter

Fronius Galvo Solar inverter

The energy management relay inside the Fonius inverter can divert solar power to a specific appliance and help avoid exporting at a low feed in tariff. All we need to do is set a power value of say 2000 Watts and once your solar starts generating more than the pre-set amount, it will flick a switch and turn on your pool pump to soak up the solar generation. A second pre-set amount can be set e.g. 1800 Watts and when then solar drops below that point the inverter deactivates the power to the pool pump. This can be a great feature at no additional cost, but it also has its limits, similar to the timer solution, if the solar inverter is putting out 2200 Watts and there are other electrical appliances being used in the house on top of the pool pump consumption, you may find that you have a total power consumption of 3000 Watts for example. This would mean that the additional 800 Watts that wasn’t being supplied from solar would be purchased from the grid at peak rate. Once again one thing that needs to be looked at is the benefit of reducing export at a low rate, verses, buying electricity from the grid at peak rate that may have been previously purchased at off-peak rate.

  1. Third Party Energy Management Options

There are a number of new products coming out that allow you to have a bit more control over how much electricity you are importing and exporting. We expect to see many more hardware and software solutions hitting the market over the next few years that look specifically at this area. The immerSUN and ASM SunnyMate are two products that are currently available that look mainly at dealing with your hot water requirements.

immerSUN Solar Energy Management Device

immerSUN Solar Energy Management Device

Rather than just flicking a switch when the solar output reaches a certain point, these devices measure when you start to export electricity to the grid and will turn your electric hot water heater on to soak up any excess solar power, rather than having it exported to the grid for nix. In the case of an electric hot water unit, there are a couple of important factors to consider that are a little different from most other appliances. Firstly they are normally being run on off-peak electricity commonly around 15c/kWh around the Geelong region, and secondly the elements can range from 2400W -3600W quite a high power requirement. By using the immerSUN device you maximise the amount of self-consumed electricity by diverting solar to the hot water element, offsetting the cost of paying off-peak rates (if you had powered it from the grid at night), but at the same time the device minimises the electricity you have to purchase at peak rates to supply power to the hot water service during the day. The immerSUN actually has three outputs, allowing you to control two resistive loads like heaters or hot water units and one multifunction relay, which could be used to drive a pump for example.

The cost of having these units installed is starting to get a bit more expensive than the previous solutions, probably up around the $800-$1200 mark, so this isn’t going to be for everyone. As a general rule, the larger the disparity between your off-peak rate and the solar feed in a rate the bigger your savings will be. For example, an average electric hot water service takes about 8kWh to heat. Here’s a possible scenario:

Feed in Tariff = 6.2 cents/kWh

Off-peak tariff = 15 cents/kWh

Difference = 8.8 cents/kWh


8.6 cents x 8kWh (energy to heat hot water) = 70.4c/day savings

70.4 cents x 365 days = $256.96 per/yr savings

This case gives a 3-5 year payback on the unit, so could be a good solution to save money. This example does assume that there is enough solar power to heat your hot water unit each day, this is quite possible with a 5kW solar array, although there may be some boosting required from off-peak mains grid required on days of low production, which may reduce the savings a little. If the difference between your off-peak tariff and feed in tariff is less, then the savings seen will also be less.

  1. Battery Storage Solutions

There has been a lot of interest in grid-battery storage solutions for grid-connect solar systems lately. There are heaps of new products coming onto the market and costs are expected to come down over the coming years. Batteries can be another way that you can increase your solar self consumption. Rather than sending that power back to the grid at a low feed-in rate, store it in your batteries and use it at night. The technology is available to do this now and more and more people are beginning to take this option up. When compared to the other options listed above, there’s a bit of a price jump. Most decent battery storage solutions will add $13,000-$20,000+ to the cost of a solar system, depending on the amount of storage capacity you are looking for and the quality of the system, but with people getting fed up with being treated badly by their electrical retailer and not getting paid much for their solar export, batteries are a solution that many Australians are looking towards to gain more energy independence.

Battery storage solutions for solar self-consumption

Battery storage solutions for solar self-consumption

As I said earlier self-consumption is important when it comes to solar power. Many people have been ill advised about the savings that they will see from their solar system, mainly due to a misunderstanding about how the feed in tariff works. That’s why it’s important to do your research and get good advice about system sizing. Oversizing your solar system may just lead to additional exports and at 6.2c/kWh it might be better to go for a slightly smaller solar array and keep some cash in your pocket. Alternately if you are able to optimise your self-consumption efficiently through the solutions described above, you’ll be able to squeeze more value out of your solar system and keep more dollars in your pocket. Smart new technologies are set to change the way we use energy into the future, whether it be solar power, energy management solutions or the integration of electric cars into our electricity network, we are in for an exciting period – I think you can expect to see our energy network revolutionised over the next 10 years.

Note that for those solar consumers that installed their systems under the Premium Feed in Tariff or Transitional Feed in Tariff for solar, the above scenarios will not be relevant. If your feed in tariff is higher than what you are paying for electricity you will see a larger savings by exporting electricity to the grid than self consuming.

For advice on solar power, energy efficiency or anything outlined in the post above, please feel free to give us a call on 1300 931 929.