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. 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 interstate.
The batteries are 2 volts x 167 AH each. This adds up to a total storage capacity of > 3800 AH (amp hours)
As can be seen in the photo I have built a battery rack from treated timber. 70 x 35 (2 x 3) and 90 x 35 (2 x 4) secured with galvanied batten screws. When I have finished the wiring and fitting the major components, I will fit the backing and lockable doors. These will need to be vented and have a thermostatically controlled ventilation fan.
The high capacity Battery charger currently resides on the top shelf at the right and the inverter on the shelf immediately below. The battery charger has the capacity to keep the battery bank fully charged. The use of the battery charger is only an interim measure until we fit the appropriate number of solar panels. The inverter delivers 240 volt AC power with more than enough capacity to run my entire greenhouse, pumps aerators and the like.
I am currently running two of my Aquaponics systems from the battery bank as a test to see just how much power the pumps actually use compared to the draw they claim on the label. I have connected to the system 1 x 80 watt solar panel via a small solar panel controller. This panel is really old and right in the middle of the day it only delivers 3 amps which is around 35 watts, not even enough to run one small pump. This particular panel is not suitable for our long term purposes but is useful to help design wiring and to test the system controller.
Solar panels will be added over time.
My next addition to the system will be a high capacity solar panel controller that will deliver regulated power from the solar panels to the battery bank. This will regulate the voltage coming from the panels to the batteries, will switch the panels off when the batteries are fully charged, or the panels stop charging as would be the case after sunset. The solar regulator will perform the following tasks.
1. It will monitor incoming and outgoing current from the battery bank.
2. Fitted with the correct shunt it can switch on a auto start generator set.
3. Will have a low battery voltage cut out switch.
4. Display battery voltage, charge current, amp hours in and out of batteries, load being drawn from the batteries at any instant, and which part of the charge cycle the battery/s are in.
Together with this solar panel regulator we will add, in pairs, 200 watt each solar panels.
In the next post on this subject I will deal with the Solar Panel load and why I have chosen to stay with 240 volt AC pumps and aerators rather than 12 or 24 volt DC pumps.