Cutting back on wasted electricity is the cleanest power source of all – as our household shows


Anthony James, Swinburne University of Technology

A few years ago, I couldn’t read an energy bill beyond the charge levied. I couldn’t tell you how energy was measured, or ultimately how its use related to making my life better or worse, let alone how it affected broader society and the planet.

I resolved to change this. I studied energy and sustainability at university, and have gone on to teach there. Throughout this time my wife and I have made many changes to how we use energy at home. Yet when we decided to take a closer look into our electricity bill, we were surprised by what we found.

There are three of us in our household now, since our son was born last year. Notwithstanding that, our metered electricity use continued to go down, coming in a little under what it was the same time the previous year.

According to our bill for the spring quarter of 2014, we used 3.79 kilowatt hours (kWh) per day, down from 3.95 kWh per day the previous year, despite the extra person in the house. (Granted, he’s a small person, but any parent can tell you how much small people add to the general load of your life, including energy use.)

We don’t feel particularly heroic about this, but when our bill also informed us that the average use for a household of three people in our region of inner Melbourne is 14 kWh a day in summer and 17.1 kWh a day in winter, it got me thinking. Even for households of two, the respective daily averages are 11.6 kWh and 14.8 kWh, and for one person, 9.2 kWh and 12.4 kWh. These are massive amounts of energy to be getting through every day.

Panel questions

Importantly, none of these figures counts how much energy is used from other sources such as gas, or electricity generated by solar panels. In our case, we don’t have gas, but we do have solar panels. So how much electricity did we use from the panels in this period? This is a harder question to answer than you might think.

Our bill tells us that we exported 5 kWh per day to the grid, but it tells us nothing about how much electricity from the panels we actually used. The retailer doesn’t receive that data – apparently, nobody does. This makes it hard to know how much energy we use in total, both as a household and by extension as a society.

Solar Panels Apartments

It is still surprisingly difficult for householders to find out how much power they are getting from their solar panels.
Biatch/Wikimedia Commons

That’s a sizeable blind spot for such an important issue. It’s as if solar-powered electricity is somehow regarded as “free” – a fraught idea to say the least. While sourcing electricity from our solar panels is (a lot) better than coal, it’s still an industrial technology.

In the absence of this information I turned to daily monitoring of our inverter, which shows how much electricity is generated by the panels each day. Subtracting what was sent to the grid, it seems that we used a daily average of about 1 kWh of electricity from our panels. Added to the 3.79 kWh on our bill, our household’s actual electricity use during the period in question was about 4.8 kWh per day, or 1.6 kWh per person – a fraction of the average for people in our neighbourhood.

Comparing per capita energy use is relevant because if living alone makes us more intensive energy users, then one of the most effective things we can do is share a place. This is all the more relevant when we take into account the embodied energy of each building, to say nothing of the related energy costs of urban sprawl, extended service provision, car dependence and so on.

But to get back to comparing apples with apples, the average three-person household used around three times the electricity we used (and probably more, given that we are including what we used from our panels, and comparing our household figures for spring with the wider average for summer, when our energy use tends to be substantially less). This raises a promising prospect.

How to get ‘free’ electricity by not using it

Consider this. Our household used around 9.2 kWh per day less than the average household in our area. Over the quarterly billing cycle, that adds up to 837 kWh, far eclipsing the 455 kWh we exported to the grid from our solar panels. In effect, it can be said that we “sourced” that 837 kWh for other (or future) uses, not by selling electricity to the grid, but by conserving it.

In industrialised societies like ours, where we tend to use far more energy than we actually need, this is a significant and genuinely clean energy source that is begging to be tapped. It is hidden, not in the bedrock of the earth, but in the bedrock of our minds, habits and expectations.

Conservation mining”, as the late sustainability professor Frank Fisher called it, is “mining” energy by conservation. Here’s a sense of how we’ve gone about it.

We’re in a rental townhouse not particularly designed with low energy use in mind, but the owners were happy to invest in a few relatively low-cost, “low-tech” changes, such as draught-proofing, insulation, thick window blinds, and solar hot water.

Beyond that, most of the changes have been to how we live. We use heaters specific to the rooms we’re in, and only when the temperature dips below 16C. If that seems low, it is interesting how we do adjust, particularly with more appropriate clothing (like Ugg boots and thermals in winter), moving our bodies more, and of course huddling together.

Cooling is a bit easier at our place, as there is a lot of tiled surface. We use the thick blinds and airflow judiciously at different times to regulate the temperature on hot days, and have a small fan the size of your hand for personal use if we happen to get successive hot days.

There are other things that play their part, like washing clothes in cold water and washing them less (though still enough). Another tip is to fill a thermos each time the kettle is used. These are strategies that require no more than an initial change of habit.

All this has certainly lightened the load on the family budget, and therefore the time we need to spend working for money (with its additional energy use). In an era where we need to reduce our energy use substantially in industrialised societies, it’s empowering to know that a better and more sustainable life isn’t so much found in new technology, as in our own hands. That’s something our young son may come to be very thankful for.

The Conversation

Anthony James, Lecturer with the National Centre for Sustainability , Swinburne University of Technology

This article was originally published on The Conversation. Read the original article.


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Understanding Batteries

Off-Grid Systems

For some households a battery system can be of great benefit and minimise a home’s reliance on the grid. However, it’s important to understand for a battery to be useful your solar system needs to be generating excess energy for the battery to store, which you can then use at night or when the sun is not out.

When selecting a battery, you’ll want to invest in a system that is most suited to your home and can drive the best return on investment (ROI). Despite a larger upfront cost, a higher quality battery may significantly increase your ROI.

    Battery systems start from $6,000 and costs can vary greatly based on the following factors:

  1. Cycle Life-Time

    The number of times a battery can fully charge and discharge.

  2. Battery Power (kW)

    How fast it can be charged or discharged.

  3. Storage Capacity (kWh)

    The maximum amount of energy a battery system can store.

  4. Battery Management System (BMS)

    An electronic ‘smart’ system that gathers data and manages the battery ensuring it does not overload or operate outside of its safe functioning zone..

  5. Inverter

    Battery systems require their own inverter if your solar system does not have a hybrid inverter.

  6. 'All-In-One Unit’

    A system which includes the battery, BMS and an inverter all in one unit.

  7. Warranty

    Length of time or cycles the battery system is under guarantee.

  8. Blackout Protection/Backup

    It’s important to note this is not a common feature of a battery system and could cost thousands of dollars to include. Blackout protection not only requires additional components but also a specialised installation and rewiring. For grid-connected homes, the cost for blackout protection can outweigh the benefit.

Additionally, if your purpose for adding battery is to go Off-Grid and become completely independent from the grid you will need to ensure your solar system can generate enough energy to power your home and your battery system is large enough to store this energy. For homes in metro areas going Off-grid is not cost effective and is only recommended for those in remote areas with limited access to the grid. Off-grid solar systems with battery start at approximately $30,000.

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