Choosing a new fridge

The fridge is critical to maximizing net export as it runs during the day when the panels are generating. I’d been looking for the ‘ultimate’ energy efficient fridge for ages, but finally just bought a standard 310L Westinghouse - smaller than the old one. Even though our family has down-sized, changing expectations of what the fridge had to provide was not an obvious or easy choice. Human instinct is to always want more, assisted by the manufacturers who have up-sized their models since we last looked 15 years ago. It was off-putting that the smaller model had fewer stars (4 instead of 4.5) disguising the fact that it uses less power overall. The new fridge saves about 1.5 kWh a day, with energy use strongly dependent on temperature..

Photovoltaic Solar Panels

The 1.5kW solar panels were installed in January 2008 after a number of quotes over several years. Even then, we did not have a handle on all the factors and advice was somewhat variable. It was important for me to see how the panels were operating so we added the optional wireless display. This cost ~$600, but added massively to my understanding and daily appreciation of the system.

Output has averaged 5kWh over the year, varying substantially over the months. While not our
original intention, we now are a net exporter to Origin Energy and are in credit. Although

Origin are probably the best company around, we have had issues with every bill since installation. For example, even though we were exporting to them, we were still being charged for 20% Greenpower.

The panels make up about half of the average daily savings we have made - but cost $10,000 (the new feed-in tariff will help here). The new fridge contributed 15% and cost ~$700. Using the dishwasher less and the clothes washer on a different cycle contributed 8%. A small toaster oven to supplement the electric stove and other bits and pieces cost around $100 and contributed 6%. The real ‘no brainer’ however, was simply reducing standby power of appliances - saving 20% for no cost and generally little effort. It needs to be emphasized that installation of the solar panels was absolutely critical in raising our awareness to bring about this action. It all adds up.

We were initially disappointed with the panel output – the peak power rarely exceeded 1.2kW compared with the rated 1.5kW and the daily average output seemed less than the 5.8kWh quoted. It took time to build trust in the system and understand the factors at play. For example, variation in the sun’s path was a revelation with trees unexpectedly blocking morning sun in summer and winter. The monthly maximum output (assuming at least one sunny day per month) indicates that our maximum output is in Autumn/Spring - influenced not only by the trees, but also lower output in higher temperatures and a panel elevation of 32° optimized for mid season.

Net vs. Gross feed-in tariff

Getting to understand the Net vs. Gross feed-in tariff issue was difficult. After the import/export meter was installed in April, the daily figures started showing how this should work for us. Our net export is averaging about 85% of the gross panel output due to our low energy use. When the 60 cent tariff is introduced this should return ~ $1000 annually from the $10,000 (from net export and reduced import figures). Not bad compared with $330 from the current Origin 20 cent feed-in tariff.

The proposed net feed-in system is confusing. It doesn’t measure what we’re trying to achieve
(lower carbon output) and forces silly behaviours. For example, you try to do washing at night
otherwise it eats into that net export - you would be effectively charged 3X normal power use. The net scheme however, does provide a very strong incentive to reduce energy use. If you don’t, the tariff could easily end up practically worthless. A gross system gives no such incentive.

Daily recording of household data

once the panels were installed in January 2008 and I started
logging their output, it seemed logical to also track our electricity use, water, gas, car, bike,
refrigerator and house temperatures each day. A Powermate energy meter was used.

Reduction in energy use

Over 12 months, we can track a drop in average daily electricity use of 4.5kWh - from a two-year average of 7.5 kWh to under 3 kWh. Most pronounced savings occurred immediately after the panel installation when we went around switching off everything we could to prevent Origin eating up our hard earned solar exports. This saved 2kWh in standby power for no cost and little effort - the worst culprits were the central heating system, HiFi components and printer. We made additional changes throughout the year and consolidated better habits. A new fridge had a significant impact mid year.

How do you make a cup of tea with least carbon emissions?

A. Electric jug 

B. Gas kettle

C. Microwave 

D. Tefal ‘Instacup’


After some investigation I concluded that our gas kettle is approximately ten times less energy efficient that the electric jug, therefore about three times worse in carbon emission (gas has a lower carbon output). The electric jug however, only heats a minimum of two cups. The ‘Quick Cup’ promises “hot water in 3 seconds” and up to 65% the energy, but feedback in Renew and Choice indicates the water may not be hot enough to actually make a good cuppa. While the microwave is less efficient than the jug, it heats exactly one cup and appears to be technically the best (just). In the end, the jug is more practical and what we use.
This exercise illustrates the thinking you have to apply time and again - to investigate alternatives, filter green wash, measure, question habits, adjust expectations and arrive at some pragmatic compromise. Not easy at all.

The iPhone as a tool for reducing your environmental footprint

I've been surprised by the ways in which the iPhone can help you lighter that environmental footprint. 

Getting around

Public transport timetables and journey planning 

Weather

Filling in time usefully

Saving energy