Backyard Aquaponics
A place to discuss aquaponics

Anyone do any cost analysis on AC v DC systems?

I don't have any analysis, but there are definitely benefits to sticking with AC. The two big things are:

1) you can run longer cable runs for your power
2) you have more choice for pumps, etc.

while not for my hydro/aquaponics, I have an emergency battery backup that I use for home use in case of power failure during storms, earthquake, etc. What I do is charge my marine battery from AC current and keep the battery charged. then I use an inverter to power AC devices. I know that there is some efficiency loss, but it is negligible for my use. Plus, I can recharge the marine battery from a solar controller or even my car (using jumper cables). and then using the inverter, I can run a 100 foot extension cord pretty much anywhere in the house or backyard.

I haven't done cost analysis either but it stands to reason that setup of DC will cost more (generally speaking) than AC but overall cost, taking into account running costs, DC (assuming solar) would have to be less over time.
The longer pump, batteries, and ancillary kit (solar - panels, controler, chargers) survive, obviously the less the costs are.
So really at the end of the day it's a hard thing to analize.
The other difficulty is that a lot of our systems are very different, and our carried locations make huge differences in the price of equipment and power, and for some even cost of water.
So unfortunately a cost analyses between one AC system and one DC system in one place isn't going to mean much to some one elsewhere.
However this is my opinion

I agree with suedepuma . Not really saying from a cost benefit which is better but from a reliability / versatility standpoint I would run with AC equipment with an inverter to run it from a battery. You can always use solar to charge the battery or if it really goes pear shaped you can use a cheap generator to run it where if you are DC you still have 1 point of failure being the battery. This is my first post here as well so see what others say but that is just my opinion.

Cheers
Kev

DC water pumps are notoriously unreliable. Until affordable and energy efficient DC pumps becomes available i recommend AC pumps.

You may save some energy sticking with DC and not losing some to an inverter but any savings you make are going to be obliterated by your devices. I have not found any DC water pumps and air pumps that are close to the efficiencies of the good AC gear.

how about these solar pump units, anybody tried them?

they are a positive displacement helical rotor pump so can handle solids and wont macerate the fish poo! if that's important to you.



I will try to get a price.

Yes, I visited a few aquaponics shops looking for parts for my setup, the guy in Cannington said his boss had tanks full of barramundi just before the last storm that cut the power for a few hours, all the fish died! So before I got any fish I went too backyard Aquaponics and brought a AC/DC air pump, that was on the Saturday, come Monday we had a storm and 1500 homes lost power that day, luckily we were not one of them as when I put the bucket over the power points that night I knocked the air pump plug so it was off when I got home after work, DOH!
I figured that so long as you have air your fish should survive, water pumping is second best if that, especially when it heats up over summer,

Slowboat- that pump isn't really ideal for most backyard AP systems. 18000 litres per hour and 35m head! Also, as it has no battery, it wont pump at night or in overcast weather. I run a mono pump here for pumping water up my hill, and they aren't cheap!

the other spec said 3 to 14 m³/day and ts only a 195W panel, looks like some body got the days and hrs mixed up.

in regard to the battery yes that would be problem.
I guess you could have a header tank and throttle the flow so it can supply water 24hrs?

it has a brushless DC motor on the pump.

yes they are more suited to high head situations, but a quite efficient.

however it would be interesting to see if the cost was viable for an off the grid system.

Arr yes my bad
I agree and I see my folly, i had not read the title properly " OFF GRID AC versus DC "
So my suggested DC set up will be way more expensive than AC as, has been mentioned, DC pumps are so unreliable, requiring replacement.
So I would say that although going AC over solar will require adding another point of failure item (inverter)
The overal cost would more than likely be cheaper to go AC

Having said that I am running a small system on a 0.6 amp/hour pump that pumps 250 l/ hour to 900 mm max head
In a blue barrel, like the byap ones, 180 litres water total on auto siphon it cycles every 12 minutes or so
I don't have it on a battery at the moment, but will soon.
I will be trying it out in an ibc soon to see how well it pumps, if it does ok, I will be running 6 of them for a total of 3.6 amps.
I intend running four of them from half way up the sump tank out to the fish tank and two at the bottom of the sump, to circulate the water around the sump.
I should start a thread four this, sorry for the post hijack

I've been investigating this further.

Apparently you can get really good really large DC motors in fact all sizes. Now this might not be relevant to most people but the pumps I've been looking at for my commercial system don't care what motor is used to run them. It can be an AC motor a tractor or a DC motor. All the pump cares about is how fast the impeller is turning.

So DC pumps are an option at a larger scale at least.

How good are the newish Aquamax 1600 DC pumps? http://www.amazon.com/gp/aw/d/B006KT5OX ... ot_redir=1

Never buy a pump without a performance curve.

You will find it here somewhere:

http://www.oase-livingwater.com/en_EN/water-garden/start.html