Backyard Aquaponics
A place to discuss aquaponics

I'm really keen on setting up a solar powered system and would like to no if any one who has done this I would love some photos

A small single IBC off-grid solar system I've built and am trialling:



Specs:

- 40 watt monocrystalline solar panel ($55 off ebay)
- 5 amp solar charge controller ($20 off ebay)
- old 12 volt car battery
- 12 volt timer (assembled from a kit from Jaycar)
- 12 - 24 volt submersible pump, (1000 - 1500 litre per hour, depending on voltage supplied)
- an esky to create a waterproof housing for all the electrical components

It runs on a 15 min on / 30 min off cycle, 24/7. The old car battery would no longer start my 4wd but has been powering this system nicely for the last 4 months or so. I think I've found a good use for old batteries

Currently I have about 25 goldfish living happily in the system, but the drawback to this current setup is it needs more oxygenation. I hope to add an air bubbler soon but not sure if I should run a 240 volt air pump through an inverter or try source a 12 volt air pump...

If you're just starting off, I recommend reading the solar articles on this caravanner home website which really helped me:

"How Many Solar Panels Do I need?"
http://hobohome.com/news/?p=263

I'm running on solar power too, but just as another load on my main system, which currently runs 4kW of PV, with 21kWh of storage in LiFePO4 batteries. My AP system is a reasonably significant load and adds about 2kWh to my other energy use, due to a 125W pump and a small air pump. That's about 20% of my total electricty usage for the past month.

That seems like a reasonably large pump.. do you need that much power for those GBs? or was it just a pump you had on hand?

*edit
Just took a closer look at your system and you have a 4500 L FT, I guess if your turning that over every hour then it takes a bit of power... what head are you pumping to?

The pump is a PondMax 8000, pumping to a bit over 1m head to start, increasing to about to 1.3m when the sump is at its low level. I'll be using this as my backup pump soon, as I'm installing a Universal Pumps Sump Pump after it arrives at the shop, it is rated at 100W, but pumps at a higher flow rate. I have 6 * 500l GBs now and will have another 2 of them plus a strawberry tower and some trees on drip irrigation soon as well, so that pump is not overdoing it by any means, in fact if the general "turn over the FT every hour" rule is to be believed, it is undersized, even for a 30/30 cycle.

Yeah the strawberry towers really make it harder since they are at a high head usually... I have 10 and originally I ran them all from 1 pump (65W 6500L/h@1m head... i think) along with 3 ibc GBs and 3 NFT tubes but eventually separated the towers because it was too hard to balance them all with 1 pump... and I had ball valves on everything.

I am planning to go solar but I want to make sure I do it right from the beginning and will probably go the 240v direction with inverter as I never hear good things about 12v pumps... I have been trying to figure ways to get power usage down so battery banks don't need to be too large.
I am also starting to think that lithium is becoming reasonable bang for buck... but I am still a bit weary about dropping a lot of money on some batteries that have little history/proven rep... solar is pretty confusing stuff if I want to go down the DIY path to save some bucks

The problem with doing it on too tight a budget is that cheap inverters are very inefficient, so you need to go larger than you think with PV and batteries. My Lithium cells are hugely more efficient than Lead-acids, which I have been using for over 20 years, and even with a good quality efficient inverter and MPPT charge controllers, you need to be able to produce about 20% more DC energy than you hope to use as AC. I've written up some results of my testing here:
http://forums.energymatters.com.au/sola ... c5108.html

With a cheap PWM controller (or dodgy cheap MPPT!) and a cheap inverter, you might need 30-50% or more extra panels to supply the same amount of energy. For one particular brand of Chinese inverter charger I have seen reports that it uses about 250W just on standby with no loads! Good quality second hand is the way to go to keep costs down- a small Latronics or Selectronics inverter is reliable and locally made, and way better quality than the cheap imports.

Or just skip the inverter altogether and go 12V...

Mine's been running for 6 months, a lot more reliable than 240V.

My only problem was after 3 very cloudy days I had to plug in the extension cord to top it up -- I need a bigger battery to handle this case.

I'd recommend:
1) All 12V operation
2) Brushless DC pump (bilge style pumps will last 3 months tops)
3) Have some status lights you can glance at when you wander past to make sure that everything's running properly
4) Lead acid is cheaper bang for buck, and safer than lithium.

My solar system is here:
http://www.backyardaquaponics.com/forum/viewtopic.php?f=18&t=14494

Thats a big call... Lithium Cobalt chemistry is the one you hear about in the news- aeroplane fires, exploding phones etc. That is not the chemistry I use, and I doubt ever would be used as a domestic storage battery. It would appear most, if not all the probems with that chemistry are due to battery abuse- overcharging to too high a voltage and overdischarging. Proper battery management systems prevent that from happening. Lithium Iron Phosphate is much safer, I think at least as good as sealed Pb-acid.

Lead-acid is certainly cheaper up front, but wont last anywhere near as long, especially when subjected to deep discharges. Pb-acid batteries are heavy and contain Sulphuric Acid, which often leaks, and it is certainly easier to make it go bang (more bang for your buck!). H2 + O2 gas evolved when they are charged (for flooded cells, sealed cells have to be overcharged) is good for a bang if you are not careful with ignition sources, such as static electricity, flames etc

http://www.batteryvehiclesociety.org.uk ... php?t=1825

I have several liPo batteries including LiFePO4... I considered this chemistry for my system but the benefits (weight, size) aren't an issue. Cost and danger are more of an issue for me.

Sounds like a dodgy by design BMS in that story, which wasn't designed to isolate the battery when it needed to, plus charging of the battery outside the safe operating temperature range. I notice the story did include a link to a Lead-acid battery fire too http://www.evconvert.com/article/electric-car-safety

I probably worded my message a bit poorly I would like to save money by doing DIY and learn a lot along the way, but I value quality and reliability so I wouldn't want to be taking short cuts on equipment... at the same time I would hate to ignore certain products just because they are not brand names, but would love some advice on what companies you have dealt with and any stores online or otherwise that you recommend and deal with?
I would like to go the lithium path myself?

Yeah since my system would just be for the AP and separate to any house system that might be built later, 12v would be great... what type DC pump do you have? I have bilge pumps but only for my backup system and wouldnt trust them to run continuously

I read that article just now too... is there any kind of inbuilt double redundancy in lithium systems, like in the BMS or batteries themselves (or lead acid for that matter) I mean sensors break, so it kind of seems like the safety checks need safety checks?