Aquaponics Off Grid Power. Backup Systems
Grid Power is very convenient for powering our every need including Aquaponics, but how reliable and affordable will it be into the future?
It is the desire of almost every Aquaponics operator to ultimately run their system independently of the mains power grid. Just how reliable and affordable will mains power be into the future is the question on my mind. Now that I have well established Aquaponics systems, getting off the mains grid power system is just another step in the journey towards self sufficiency. I have been dreaming about this since I don’t know when. Just where to start and at what level? As one quickly discovers, it can become an expensive exercise.
The mains power grid is just so convenient, plug the pump and aerator in, switch on and that is all there is to do. So why take on such a project?
Here are a few of my reasons,
1. Sick of pump difficulties. Pumps fail or shut down for a number of reasons and many (but not all) of the reasons will be eliminated when going “off grid”
2. Mains power grid outages due to storms, car crashes, mains power grid system maintenance, or for a variety of other reasons.
3. Off grid will be the ultimate backup system.
4. Sick of safety switches tripping out. Submersible “pond” type pumps often, over time develop earth leakage problems which will cause the safety switch (earth leakage) to shut the pump down.
5. Power bills going up and up. The cost of mains electricity has risen by more than 35% in the last 18 months and is tipped to double in the next 12 months or so. Some States of Australia are tipped to go even higher
6. I just want to be more independent – self reliant and get off the grid eventually – a.s.a.p.
As I see it there are different levels of power independence.
1. Grid connected solar panels.This arrangement will supplement the running cost of
your Aquaponics system. It will not provide any back up ability because if the mains power grid goes down then you have no power from the solar panels. A small battery back up system triggered by a Power Fail Switch is an absolute must in this instance. This is possibly the best first step for most home based Aquaponics systems. It gives you a tangible benefit immediately both for your home and your Aquaponics system.
2. A stand alone solar panel with a battery of sufficient capacity to run your system on a bright sunny day and at night your pump/s are switched off so that only an aerator runs from the battery. A stand by generator set would be necessary in the case of prolonged inclement weather or an auto switching device to switch to mains power once the solar panels stop delivering sufficient power to the battery.
3. Solar array and battery bank of sufficient size to support your Aquaponics system round the clock and for several days in the event of inclement weather. To be totally independent of the grid power a suitable generator set would be needed with auto start once the battery voltage dropped to a pre set level.
A couple of years ago I installed a solar grid connected solar system on my house roof. It is only one kilowatt which I have discovered is just nowhere enough for the average household to make a noticeable difference. It works just fine and it does help, but is not enough to completely offset my household power requirements.
I really want to be completely independent of the power grid system both at home and in the workshop / Aquaponics garden area. I am aiming for a large solar array with a substantial battery bank and a auto switching diesel generator set. Ultimately, I will also fit into the system some wind generated power. I have figured that I can move towards this goal step by step as funds and time allow. A really well functioning stand alone solar system can be built piece by piece with proper planning.
My project has had a kick start with the acquisition of a decent battery bank courtesy of a client who was moving house and upgrading his “off grid” system. The money I paid him for the batteries was so little that it can only be categorised as a gift. Thanks mate !!!!
I have since discovered the shortcomings of a large battery bank connected to a inverter. Most , if not all inverters are set to cut out/switch off when the battery voltage drops to 10 volts. Usually there is a warning buzzer at 10.5 volts. This is done to protect the battery bank from discharging to far and thereby damaging the batteries.
This governs the the length of time your pump/s can run during the night or when there is a succession of very low light days such as during heavy rain. The load on my battery bank is a total usage via the inverter of 420 watts at 240 volts. (7 pumps at 60 watts each).
I have found by observation that this usage will run the battery voltage down to 10 volts in around 7 hours at which point my inverter switches all the pumps off.
Not very long really. It is therefore not good for me to run my systems, at this time, off my battery bank, charged only by solar panels during the day. There is not enough battery storage to see it through the night until charging from the panels begins again shortly after sun-up.
The energy from the sun needs to be utilised in another way to store up energy for use during the night.
Right now I am using my battery bank strictly as a backup system. There is only a fan and couple of aerators running via the inverter. I have rewired it to a 24 volt system and have run power from the battery bank at 24 volts DC to all the fish tanks. Each group of tanks (3 groups) has it's own Power Fail Switch that will switch on a 24 volt x 500 gph pump in each fish tank if the mains goes off at any time. All 7 pumps draw only 1 amp each , so a total load of 7 amps. This will run for around 72 hours before the battery bank voltage drops to 10 volts.
For future posts.
Pump failure not related to power outage. How to take care of that possibility.
Posted By Murray Hallam on 18th February 2012
Updated : 18th February 2012 | Words : 1152 | Views : 2759 | Comments : 11
I've learned most I know from you I live in the u.s. I've designed a few aquaponics systems and hope to make a business out of it. could you tell me what kind of gravel is p.h. neutral and cheap, please.
Posted By Matt Renini on Monday 23rd April 2012 @ 17:43:47
I am sorry I cannot help you with that. It changes from county to county. You need to do research in your local area. Be careful of gravel that is high in limestone.
Posted By Murray on Monday 23rd April 2012 @ 17:43:47
My understanding is that the primary issue for aquaponics in a blackout is fish death (caused by lack of dissolved oxygen). It seems that there is a solid link between stocking density and system energy requirements - if true, then one of the quickest passive measures for increasing system tolerance to power failures would be to reduce stocking density.
Fault tolerant systems tend to be onerous to implement, and one must make some hard decisions about what is fiscally and practically necessary. The very first question I would be asking is how many days of blackout are you looking at in a given period, and how long are those blackouts going to be? It's a trade off between investment and safety, but I don't see how you can run a system with considerable energy requirements without making it.
It may turn out to be more economical to harvest (some or all of) your fish and put them in the freezer than fight to run a system at full strength with no power for an extended period. Can a system be run on alternative nitrogen sources (manure?) temporarily? How long before the plants suffer? I suppose what I'm really asking is how long can a system be run in a reduced capacity? Reducing the energy demand is going to make whatever energy you have go that much further.
Another aspect I'd be interested in hearing your thoughts on is monitoring and alerts. Anyone that has ever been near a redundant power system in a blackout knows that they bring a lot of attention to themselves with audible and visual alerts. What alerting and reporting systems do you use to alert you to a failure state in your system?
Posted By Stuart on Saturday 18th February 2012 @ 10:39:43
Hi Stuart, Most home Aquaponics systems are lightly stocked compared to stocking levels in Aquaculture or commercial sized Aquaponics operations. However, if there is an outage of power to the pump for only a short period of time disaster strikes due to rapidly lowering dissolved oxygen levels in the fish tank. In storm season there can be blackouts lasting for a few minutes to several hours. A battery backup system needs to be able to carry a system for the length of time needed for the owner to be alerted and to be able to take some kind of action such as starting a gen set.
On alert systems, I feel that an alert system that messages the mobile phone is possibly the least intrusive for the neighbors . Some good soul needs to make an " App" for the I phone or something similar. I do not bother with alert systems because I live in a rural area and someone is always on the property. I would like to know more about alert systems.
You make excellent points.
Posted By Murray on Saturday 18th February 2012 @ 10:39:43
I am running my aquaponics system on solar and only using a couple of deep cycle heavy duty truck batteries, 6 volts each wired in series to give 12 volts.
This power is sent to an inverter that produces 240 V AC and drives my pump that draws 90 watts (6800 l/H).
The to the inverter is switched on through a micro-processor circuit that is continously cycling, 6 minutes on, 20 minutes off. This operates a solidstate DC relay that switches the power on and off with no moving parts to go wrong.
Because the pump is switched on for only about 12 minutes per hour, the batteries can stand being used all night and the next day my solar panels have more than enough to fill the batteries again and also drive the pump, 6minutes on, 20 minutes off.
The cost of the micro-processor circuit and the solid state relay worked out cheaper than making auto syphons on my 8 growbeds, and it also saves on power too if I decide to run it from the mains power for any reason.
Posted By Reg Pye on Saturday 18th February 2012 @ 09:12:02
Timed systems definitely have advantages. The down side I have found is water quality. It works fine so long as stocking densities are kept low or a poor water tolerant fish species is kept such as Tilapia. ( We are not allowed to have Tilapia here in Australia)
I am switching a couple of my siphon systems back to timed systems for the purpose of plotting the water quality in conjunction with power savings. Your post has inspired me to push on a bit harder with the tests. Thanks.
Posted By Murray on Saturday 18th February 2012 @ 09:12:02
Can you let us know some more info like what pumps you are using ? It seems like the amp usage is very little.
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