One thing most people don’t take into account when running an aquaponics system is – power failure. It often strikes when people least expect it. Many experienced aquaponics people will tell you the following tale. Their system was running perfectly for over a year. The fish were ready to harvest. Around Christmas, relatives came to visit and over the course of the day, the kids were looking at the fish and one of the children pulled the power cord out of the mains that was supplying the main pump in the aquaponics system.
No one noticed that the fish had all died until the next morning.

A battery backup system in Aquaponics

Sometimes people do it foolishly themselves. They need the power to run a drill or circular saw on the weekend. Finish their project and forget to plug the aquaponics system back into the mains. The aerator is switched off and no oxygen to a tank full of fish means the end to a dream – very quickly. It can happen to us all.

Thats why battery backup systems are a wise investment. You will never appreciate having a battery back up system installed – until the night of a storm and the power gets suddenly turned off. You can see it in action in Fig.1 squirting a stream of water into the fish tank.

A small 12 volt bilge pump keep the water in the fish tank circulating and splashing the surface. Dissolved oxygen gets returned back into the water and the fish are able to survive – for as long as the little bilge pump is able to function.

So how does the 12v pump spring into action in the event of a mains power failure?

You will notice in Figure 3 we have a 12v car battery and behind it a small box or backup power fail switch with a relay switch. While there is 240 volt power the relay is held open and no 12 volt power flows to the 12 volt water or air pump. When 240 volt goes off the relay closes and 12 volt power flows through from 12 volt battery to the aeration  or bilge pump device. The instant the mains power goes off the 12 volt system will start, and the instant 240 volt mains power is restored the 12 volt system switches off. Very simple.

Battery’s do lose their charge over time. We’ve made a modification to the backup system by fitting a very inexpensive 5 Watt solar panel to trickle charge the 12v battery every day and keep it fully charged. You can buy a small solar panel for charging battery’s with clamps on ebay for around $60. We’ve noticed from hard experience that unless you  recharge the battery regularly, come the day there is a power failure – the battery may not have a sufficient charge to do the job properly. Our old battery ran out of grunt after 2 hours. Not long enough for our liking.

With a little solar charger constantly trickle charging the battery for only an hour a day – we’ve found its enough to keep the system full charged and able to keep the system running all night if the need arises.

There is no need to mount the solar panel in full sun all day. You don’t want to to over charge the battery and risk boiling it dry. We have positioned our panel on the western wall of the house so it only captures an hours sun at sunset. That seems to be more than enough to keep the batter charged at 13.9 volts which is fully charged and more than enough to do the job. A inexpensive multimeter Fig 4 is also a good investment to reassure yourself that any backup system you have installed is functioning properly and at full capacity.

But the best investment for ease of mind is a portable petrol generator. Fig 6 Keeping a aquaponics system running is only as good as your backup plan.  You might be lucky and never experience a power outage. But if you ever do notice that the lights are suddenly out or something has tripped the mains – only then will you suddenly wish you had installed a backup plan.

While we were shooting the Permaculture Soils video with Geoff Lawton, we noticed an array of shiny solar cookers being assembled on the jetty at Zaytuna Farm. Barb Ford from Brisbane was cooking the afternoon lunch for the woofers and students on the farm.

Taking a break from our filming, we asked Barb to give us a run down on the various cookers she had on display and explain their uses. Not all Solar Cookers are the same. Some act as ovens whilst others act as direct burners.

I always had the idea that it took forever to cook a meal under solar but as I discovered, this is not the case.
Barb soon whipped up some Australian Damper, a boiling pot of coffee, scrambled eggs and a delicious stew that we ate for lunch.

The amazing part is that you can make a solar oven from just about anything. As Barb explains in the video, old pizza boxes make great solar cookers, but its probably best to use the big pizza boxes to be more effective. In fact she says election posters can be re purposed to make great solar heaters and actually prove to be more useful than the candidate they depict!

Geoff Lawton later explained to us that Barb is in fact a medical doctor – studying to become a woofer on the farm!
What a remarkable woman and career combination!

We recently installed a 1  KW solar panel array above our office here at Ecofilms. I must admit we didn’t give it too much thought until the installers arrived with the solar panels.
Feeding back to the grid is one thing but having a inverter box bolted to the wall of the office with it’s red blinking lights constantly flashing makes you take a closer look and watch how much actual Kilowatt energy is really being captured by these six panels?

This got us thinking about about our location and if there is some sort of chart or calculator available on the internet than can tell you how much sunshine is available to you on any given month of the year and what kind of performance you can gain for your system or how many Kw can be captured in your geographic area.

Somewhere there must be a chart available to look at and compare the data. Well there is but you do need to  know a couple of things about your system and place where you live.

There are a few calculators available online. Some overly complicated with all sorts of parameters you can fiddle with. Not being much of a geek a lot of the info left me more bewildered than illuminated. However, you do need to know a couple of details. Your Latitude and Longitude. Typing those two words into Google plus your location quickly gives you the coordinates, but be careful and double check as the information as not all information you get on the internet is accurate.

Sun Chart Calculator gives you a pretty nice looking sun chart based on your location.
The chart can be displayed as either pdf or png graphic and can be useful in understanding the elevation angle and azimuth angle of the sun over your house.
The chart has many options and can chart the sun’s performance over the entire year.
The sun path is charted or plotted in Cartesian coordinates and the parameters can be tweaked based on whether you live in either the northern or southern hemispheres.

The Renewable Resource Data Center (RReDC) provides access to an extensive collection of renewable energy resource data, maps, and tools. An interesting calculator to try is the PVWatts performance calculator. There are two versions to try. One based for US residents and a rest of the world version. Here you should consult you solar panel handbook for energy ratings if you know them as many parameters can be set such as the size and power of your photovoltaic panels etc. We used the default settings to verify the fact that – yes if you live in Queensland Australia – you do get a lot of sunshine over the year. More than most other cities around Australia.