My Autonomous House

Dean Buchanan
Monday, 14th October 2013

Nearly 40 years ago, Dean Buchanan dreamt of building his own autonomous house. This year he installed the final piece in his design: a photovoltaic system.

Many of you will not remember the UK’s first oil crisis which pushed up the price of coal, which led to the miners working to rule, which led in turn to widespread powercuts. My grey hair is testament to the fact that I was a witness to the 1970s and I have memories of trying to study by candlelight while the nation went on a three day week to try and conserve fuel. Such recollections underlie much of my approach to how I now service our home.

It was also in these dark economic days that I started work. Part of my first wage in 1976 went on a copy of Brenda and Robert Vale’s book The Autonomous House. They defined an autonomous house as: “A house operating independently of any inputs except those of its immediate environment.”

In its purist form such a house would not be linked to any mains services: electric, gas, water or drainage. It would rely wholly on the sun and wind and rain to meet all the occupants’ needs. I found their vision of a self-sufficient architecture an inspiration and I spent much of my youth dreaming of building my own autonomous family home.

We finally began building our house some 20 years ago and I tried to incorporate all my knowledge of sustainable design. The house is planned as an elongated rectangle with the long walls and roof facing south. All the windows face south to benefit from a passive solar gain.

More recently we have undertaken additional works including: adding external insulation, installing solar-thermal panels to make hot water and fitting a log fire in the lounge.

The last 37 years has proved a long and winding road but on 24th August 2013 my youthful dream finally became a reality when ENRG Installations Ltd, a company set up by my friend Norman Phipps, installed photovoltaic panels on the roof of our house and switched them on!

Specifications

The system has three main components. The main element is an array of photovoltaic (PV) panels on the roof. The panels are Clearline PV30/500 manufactured in Cambridge by Viridian Solar. Each panel is 3,000 x 1,173mm and uses monocrystalline silicone cells to generate a DC electrical current in sunlight. This provides a Peak Power of 485Wp and our array of seven units promises a total of 3,395Wp.

The whole system is controlled by a Nedap Power Router located in the basement. This sophisticated piece of kit, manufactured in Holland, manages and optimises the self-generated electricity in the house.

As a priority the Nedap system feeds the current to a bank of twelve 2V lead-acid deep-cycle batteries. These are wired in series providing a total capacity (C20) 560A/h at 24V. The system carefully monitors their performance to maintain long-term efficiency.

The Nedap unit has two built-in control relays that can be programmed to provide power and lighting to the house once the batteries are fully charged. It includes an inverter which changes the panel and battery current from DC to AC that can be used by standard appliances. As a final setting, the system can export excess energy to the grid or it can go into standby. We have decided not to sell any surplus. Export tariffs (what you sell at) are lower than the import tariff (what you buy at) so, for me, it makes more sense not to buy it in the first place.

The total cost of the system was £12,000. Based on last year’s electricity bills this would take some 18 years to pay-back. However based on an annual price rise of, say 10%, pay-back would only be 10 years.

Autonomous Advantages

The concept of autonomy in an electric generation has several appeals. Firstly, and perhaps most obviously, with the new installation we are able to gain free electrical power from the sun for the house using the PV array in the daytime and the battery at night. It is almost axiomatic that energy prices continue to go up and I hope that this investment will secure us against any future price rises.

Secondly, many of you will be aware of the concept of the approaching ‘perfect storm’ which may result from the combined effects of Climate Change and Peak Oil. There is a good deal of talk about energy security and blackouts in the media and at a personal level the installation of a PV system ensures that we will not be left sitting in the dark. I also believe that the widespread installation of such decentralised power production would be a vital step towards building national and local resilience to the inevitable changes the future will hold.

Finally, and from my own point of view perhaps most importantly, this investment means that we are in charge of our own energy supply. This gives us freedom from the centralised utility network of power stations and transmission lines which the now infamous 1% control.

In this modern world everything is run on electricity and in the UK we are wholly dependent on a supply generated by only 18 energy companies. Such a centralised system denies individuals their independence.

If we want to regain control of our lives we need to resist this detrimental dependency. We need to become in-dependent.

The French farmer, environmentalist and philosopher Pierre Rahbi evokes this poetically in his book, Vers la Sobriété Heureuse:

"From now onwards the most important and most beautiful act that humanity will need to perform will be to meet its vital needs in the simplest and healthiest way. Cultivating one’s garden or practicing any creative activity of self-sufficiency will be considered a political act, an act of legitimate resistance to dependency or the enslavement of man." 

A broad grassroots movement towards autonomy on the domestic scale could evolve into a wider vision of a decentralised society where every family generates and controls all aspects of its heating, power and lighting... a future where each person is responsible for his/her own decisions about life.

After nearly 40 years of steady effort I have finally taken the step towards autonomy. As a household we now generate our own electricity. We are no longer dependent on the mains supply and, just maybe, we have taken our first step towards freedom. 

Dean Buchanan is an architect based in London. Since completing an MSc in Advanced Environmental and Energy Studies at the Centre for Alternative Technology (CAT) he has been active in promoting environmental issues through his writings and talks.

Further resources

Watch: Skill sharing: making handmade solar photvoltaic panels in developing countries 

Watch: How to store solar electricity from off-grid panels

Read: Cheap and potentially free to build and free to run houses

Read: Making DIY solar panels for your off-grid home

Read: Is solar still worth it?

Converting to an eco-friendly home: the complete handbook for just £7.99 on our Green Shopping site

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Stevewa34 |
Fri, 21/02/2014 - 14:18
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