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Kaizen088

Off Grid Solar Fish Room

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I picked up my deep cycle battery the other day (24v/600Ah).

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The first thing to do will be to convert it to 12 volt (this will also double the Ah capacity to 1200Ah), quite a simple thing to do but will get it done professionally do to maintain good current flow.

So the next step is to work out how much current the whole system will draw, I'll also be running a few things inside the house (LED downlights and laptops etc.) off the system as well. Once I work out roughly what it will draw then I should have an idea on how many solar panels (100w each) I'll need. I'm thinking around 5-10 (500-1000w).

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I've decided on an MPPT controller to regulate the charging of the batteries.

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I already have a 600w inverter for immediate backup if we have a blackout before I get the system up and running but will probably look at a 5000w inverter to run powerheads/cannisters etc.

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Edited by Kaizen088
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I've found a 12v 100l/min air pump (it may be a bit of overkill but there are smaller models available) for a reasonable price so I'll run that straight from the battery as it's more efficient to run straight off 12v than 240v through an inverter.

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Lighting will be 12v LED, either downlights or waterproof strip lights. I've worked out that you can run standard household 12v LED downlights on either AC or DC so that makes it easy to sort out the lighting inside the house straight from 12v DC.

Any feedback from people who have experience in Solar Systems (especially off-grid) would be much appreciated.

Edited by Kaizen088
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Solar Panel > Solar Regulator (to control battery recharge/prevent overcharge) > Battery > 12 volt appliances.

This is the basic plan. The better solar regulators allow you to bypass battery in daylight since there is energy to spare. You can also build in a low voltage disconnect which will cut your appliances off when necessary to prevent batteries from total drain but I doubt this will ever be needed with your battery capacity. Also do your costings as it might be cheaper to just use a 240 volt smart charger instead of solar panels as you don't really need to go off grid.

Or if you want really simple; Solar panel > 12 volt appliances. Works great in daylight only. I use this on out door ponds.

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I'll try to run as much on 12v DC as possible (any voltage conversion will create heat and energy losses).

There are some things such as the canister filters and Otto powerheads that won't run off DC so they're about all that should run off AC in the fish room.

For lighting I have found these which work out at $35 with postage.

They are marine grade so won't corrode like the 'waterproof' 300 LED 5M rolls you get off ebay.

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I'm still looking at options for the charge controller side of it and thought of the changeover relay setup initially for DC backup when there was a blackout.

If the system did stop working then I can always plug back into 240v with little fuss (so long as I retain all the stuff that will be replaced with 12v such as the air pump and lights).

Ideally like to go off the grid completely for the fish room so I don't have to have the ongoing and ever increasing power bills. Last one jumped up by $200. We currently pay $700/quarter which I know is small compared to some of you with big families and many more tanks.

Edited by Kaizen088
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Thanks [MENTION=885]smicko[/MENTION] I will probably use the chiller on the IBC which is not in the fish room.

The fish room is in the process of being fully insulated with a 75mm layer of foam all around so hopefully I can keep the heating/cooling to a minimum.

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I have a small portable A/C which is rated at 1350 Watts/6.5A current draw which could potentially run of the 5000W inverter to keep the fish room cool.

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I think you need to decide whether you want to go totally off grid or not first as that dictates what equipment to buy. Next is to decide on 240 volt AC or 12 volt DC. Its pretty easy to replace the canisters. A large sponge tray above your tank that is gravity fed would do that for example. So would an open top bucket containing a 12 volt water pump.

There is a lot of appeal in keeping the 240volt AC but as you already know, this is energy inefficient and will add to setup costs. I can see the 5000W inverter failing as I have gone through about 4 inverters already. It may be better to get several smaller ones to spread risk or have another 5000W inverter kept as spare.

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So it is not uncommon for inverters to fail .

I have had quite a bit of trouble with smaller ones that I use on the fourby when I go on Native collecting trips .

I thought big ones would be more reliable than the "made in China" ones from camping stores .

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I ordered some LED lights from eBay which arrived today.

6 Metre Boat Fishing LED Lights Caravan Camping LED Lights 12V | eBay

There's 72 individual LED's in groups of 3 x 24, not bad value at $16.

The eBay ad describes them as 6M long but its 6M (actually 574cm) including the wires that join each bank of 3 LED's.

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Still puts out a fair amount of light though and they're rated at .35Ah (4.2W)so very low current draw.

I'll probably get another 2 to do the fish room.

This picture is taken at night with no other lights on in the house.

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Edited by Kaizen088
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There is a lot of appeal in keeping the 240volt AC but as you already know, this is energy inefficient and will add to setup costs. I can see the 5000W inverter failing as I have gone through about 4 inverters already. It may be better to get several smaller ones to spread risk or have another 5000W inverter kept as spare.

Since getting the battery cell arrangement modified I'm now looking at building some redundancy into the system by having two banks of 12 volts at 600Ah. Initially I'll charge each bank alternately each day from 5 x 100 watt panels. When funds permit then I'll install another 5 panels and charge each bank daily. If a cell goes down on one bank, I should still have enough reserve power to run the whole thing off the other bank. This will mean I will need two charge controllers but they're not that expensive.

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If your going to use the same solar panels to charge on alternate days then it is safer to keep the 2 batteries in parallel to give a single 1200Ah bank. The failure point won't be batteries and even if it is, the other battery bank will carry the load so there isn't much to gain.

It's only worth having 2 separate systems when you really do have 2 separate systems. I would just carry spares and use as one system fornow. Besides, there are many other ways to build failure safeguards into a system. The primary aim is to keep your fish stock alive, not have your airpump never fail. A simple but effective example is to have low stocking rates and to keep 2 lots of your prize fish separate.

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Okay so from all the research I've done and drawing from my 20 years experience as an Auto Electrician and Electric Forklift Service Technician I believe that if you run the batteries in parallel you will never get the two banks to charge properly/evenly. This will then cause the most expensive part of the system (the battery) to fail prematurely or at least shorten the life of the batteries. Part of the reasoning for the two systems is that if I were to run the two in parallel I'd need around 1kW of (10)panels to keep the system topped up each day. My reasoning behind running two 600Ah systems is the only extra thing I'll need to buy is and extra charge controller which isn't terribly expensive. Yes I'll need two inverters but I agree with you that 2 x smaller inverters may be a better option anyway and I'll also be running some lighting and other stuff upstairs in the house anyway. So to keep initial costs down while getting the system up and running I will just get .5kW of (5)panels and see how they go before getting another 5 panels. As I said before I don't want to change the (Otto) filters and 2 x cannisters I'm using and they only draw low current. I'll be using a large air pump and have one or more sponge filters in each tank. The whole point of the exercise is to go TOTALLY of grid.

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If you have years of proffessional expetience in this field, then I defer to your judgment about charging but essebtially you are only reducing the battery size - capacity. If the rechatger cant cope with your daily load (draw) then the battery size shouldnt matter - unless its too small.

And if your charger isnt able to charge the alternate battery in tine ( very cloudy days for exampke) then what will you do ?

I agree that 2 small separate systems are best but only if they are totally separate. However if thats not too far off then you can try sharing the solar panels. The other choice is to go backwards and use 24 volts as a single battery.

Provided you take other precautions, I expect a week without any power at all shouldnt be a problem.

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If you have years of proffessional expetience in this field, then I defer to your judgment about charging but essebtially you are only reducing the battery size - capacity. If the rechatger cant cope with your daily load (draw) then the battery size shouldnt matter - unless its too small.

And if your charger isnt able to charge the alternate battery in tine ( very cloudy days for exampke) then what will you do ?

I agree that 2 small separate systems are best but only if they are totally separate. However if thats not too far off then you can try sharing the solar panels. The other choice is to go backwards and use 24 volts as a single battery.

Provided you take other precautions, I expect a week without any power at all shouldnt be a problem.

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