Five people, one house, one sun - that can be enough

Five people in one house in the city, one lot of solar panels and batteries, and one sun.

No electricity lines to the house.

How does that work out?

Well, the sun is above . . . all over Earth . . .

Here's another guest blog by US intern, Jillian Meares who has been analysing the data provided by the energy system.

More data, more facts - and a dash of hope.

• Solar energy production and use

• Solar energy production and use

Energy Analysis of Sydney’s Sustainable House – 31 January to 26 March 2019

[Analysis by US intern, Jillian Meehan.]

Overall, the production of energy from the solar panels exceeded the house’s energy usage almost every day between 31 January to 26 March 2019, and, of course, this is what you would want to see. The house was able to run on the sun’s solar energy without necessarily having to take from the batteries.

Only 9 out of the 55 days shown had higher energy usage than production values. During these days the house’s batteries were relied on more than direct sunlight for any energy needs.

The average daily energy produced during this time period was 9.57 kWh while the average daily energy usage was 7.99 kWh. This can be broken down to a daily average energy consumption of 1.6 kWh per person (five-person household).

Compared to the typical Sydney five-person household, Sydney’s Sustainable House uses much less energy, especially considering almost all of its energy comes from the house itself, instead of an outside source. [

•   Daily average energy use: typical five person household v Sydney’s Sustainable House

Daily average energy use: typical five person household v Sydney’s Sustainable House

An average Sydney five-person household would use roughly 52 kWh per day, so that’s a daily average use of 10.4 kWh per person which is more than 6 times greater than what is used in Sydney’s Sustainable House.

And it costs much less to live sustainably as well. When Sydney’s Sustainable House housed four people, annual costs were lower than $300 and this was for gas to which the house remains connected. For a typical Sydney four-person household, electricity bills are around $3,289.64 a year. This is clearly a significant difference – just under $3,000 saved a year.

Sydney’s Sustainable House uses solar panels supplied and installed by MV Solar. The solar panels’ monitoring system provides alerts when there are instances like lost communication or low battery voltage.

Since the beginning of March, there has been an increased amount of low battery voltage alerts coming from the system. This is most likely due to the increased amount of cloudy days there has been in Chippendale recently—less direct sunlight is able to be used for the house’s energy needs, and less energy is able to recharge the house’s batteries. There were low battery voltage alerts everyday of March besides the 6th, 16th, and the 20th-25th, and there were alerts 8 days in February (1, 3, 8, 14, 18, 21, 24, and 28). However, by looking at the online portal for the monitoring system,, it shows that every one of these alerts were cleared in a matter of minutes. This was achieved by turning off appliances to reduce the load on the system

What does a low battery voltage alert mean?

This is where Managing Director and Solar specialist for MV Solar company, Michael Valantine, came to the rescue. He stated that “battery voltage is a measure of electrical pressure from the batteries.” When the house’s battery charges are low (like on a string of cloudy days) the voltage is reduced, and it continues to be reduced when more energy is used by the house. So, when the system detects a low voltage, the inverter will produce an alarm to let the household know what’s going on. Michael goes on to say that “when the sun comes out the panels via the chargers and inverters input electrical energy by raising the electrical pressure or voltage higher than what the battery is trying to put out. This then forces energy into the battery and commences to charge them. The overall system battery voltage is then lifted and continues to climb while the batteries recover their charged energy.” At this point, there is ample energy from the batteries and solar panels for the house to use.

Limit on data monitoring system

Only two people can receive alert notifications form the monitoring system – the owner and an installer.

The installer does not necessarily have to be someone from the solar company. From the owner’s portal (in this case – a tenant), you can add someone into the system which will allow them to receive alert notifications. Scott Thorley who works with internal technical sales and support at Selectronic reiterates: “Record the Device ID and Serial number under the settings tab of the “Owner” portal, log into your portal and click on add system then tick the “Installer” box.”

Yes, but what’s it like to live there with five people?

In discussing this data with Louisa and Mark, the parents in the five-person household, some very helpful comments were provided by Louisa who has offered these comments for this blog:

“… we did run out of power on Monday 18th March. Thus, we had the system turned off for approx. 12 hours on the 18th and again on the 19th to try to generate some power that could be used in the evenings - this is why the usage on those dates is so low. We were then very conservative with power for the remainder of the week so as to give the batteries a chance to recharge (i.e I did washing at my mother’s and sister’s houses that week, we spent most of the days out of the home to minimise usage etc.).”

“… our usage tracks the production fairly consistently whereas in a standard home you might expect that usage to be more consistent on a day to day basis. This fluctuation in usage is a reflection of how we manage the system… For instance, on a really sunny day I know that I can do more loads of washing or run the dishwasher, and when it's overcast I tend to avoid doing washing or limit it to one load. (For a family of 5, using an 5kg washing machine, two loads of laundry per day is generally generated and for the dishwasher as it's a ‘half size’, it needs to be run twice a day. This means that on days like today where there is less sun, less washing happens and that will need to be caught-up when the sun is shining).”

“Lastly, in noting that our energy usage is lower than the average Sydney house, this is absolutely true. We live differently to achieve this. We don’t have air-conditioning in summer, all washing must be done during peak sunlight hours (so someone has to be at home during the day if they want to do washing). We limit the use of power in the mornings (50% of the time we don't make toast for breakfast as there's not enough sun early in the day). Each off-grid home will be different, as each home will have its own climate, micro-climate, family situation, and design eccentricities. It’s important to communicate the lived experience of the home alongside the data."

Why is the use of sustainable technology, like solar panels, so important?

We all know that solar and battery technology is an environmentally-friendly approach to energy consumption, but - to what extent?

According to Andrew Blakers’s article “How to neutralise your greenhouse gas footprint”, the average Australian emits 21 tons of carbon dioxide per year.

Although there are many contributors we humans make to pollute Earth’s air with our carbon emissions, electricity alone is the largest single contributor.

However, with the rise of clean energy, like the use of solar panels and batteries, people in cities and countrysides have the power to reduce their carbon footprints and contribute to the fight against the global crisis of climate change.

May the sun be with you, and upon your roof.

Detailed graphs are below - here you can see the weekly breakdown of Sydney’s Sustainable House’s energy use and production between 31 January and 23 March 2019.

[Analysis by US intern, Jillian Meehan.]

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