SOLAR PROJECT (Matt's 2nd system back up)

mattyry

My plans are to integrate another 300l GB with a small pump to the FT (between 15w - 25w) This will be powered 24/7 (or via timer if needed) with a 100AH AGM battery and being charged by 240w solar panels. The idea is to keep the fish happy and the water conditions stable if their is a power outage.

Purchased solar cells off Ebay which came as a package to complete the wiring.

Finished the soldering to 1 of 4 60w solar panels today and tested it in the sun
3.5amps @ 20v = 70w I'm excited!!!

Just another 3 more and then I'll have to build a frame to protect them

Better get my AP system up and running again.

If anybody has any tips or can see me heading in the wrong direction in regards to solar and AP please let me know!

Matt

Aquastud

What if you get a week of cloudy weather? At the moment the price you pay for solar and all the accessories to make it work, it will never pay for its self. The only system that is viable at the moment is the government backed system that puts all power produced back in to the grid, and this is only if they continue to pay 60 cents per KWH to do so? My system uses low wattage pumps and I have a KWH meter connected to it, and I am only using 0.75 KWH,s per day, which works out at approximately 15 cents per day. Do the sums and unless you haven't got power available it is simply not worth while.

mattyry

Aquastud wrote:

What if you get a week of cloudy weather? At the moment the price you pay for solar and all the accessories to make it work, it will never pay for its self. The only system that is viable at the moment is the government backed system that puts all power produced back in to the grid, and this is only if they continue to pay 60 cents per KWH to do so? My system uses low wattage pumps and I have a KWH meter connected to it, and I am only using 0.75 KWH,s per day, which works out at approximately 15 cents per day. Do the sums and unless you haven't got power available it is simply not worth while.

Yeah Aqua you have some valid points in regards to the cost of pay back in which I agree. I believe that Melbourne flaky power system isn't get any better in regards to reliability. It's only a mater of time before the infrastructure will be upgraded which will cost a fortune and we will end up footing the bill in the price we pay per KWh. For a good back up system with switch, charger, battery & pump ends up costing at least $400 + the cost of running it. (you have an awesome looking back up system, how much did that cost?). My system should be able to keep 50 - 70 fish and if I was to lose my fish, this would cost me at current fish prices a lot of money (current price for trout is about $18 Kg whole fish, at 750g per fish that's $940). I estimate that this solar system inc pump, solar charger, battery, cells + frames will not cost more than $1000 to build. So far it's been a terrific learning experience. oh yeah! I'm doing my bit for the environment, I like the sustainability factor it has.

Regards
Matt

earthbound

we ran our system on one 65W solar panel and it did well though we only had it stocked at fairly low levels.

Privatteer

I assume you'll put in a blocking diode to prevent reverse current at night/low light.

25Watt load.
25w/12V = 2.08Amp
2.08A x 24hours = 49.92Ah required a day.

I'm going to assume the amps you stated are short circuit amps, so real operating current is likely to be a max of 3amps under full sun.
4 panels =12Amps max.
Lets say you get 4hours full sun for a winter calculation of daily production. Rough value worked off from my solar system.
At a guesstimate just producing enough at 48Ah daily to charge during winter. Ignoring any charging losses.

My concern is the 100Ah Battery. During winter you'll have more than 12hours of dark/low light. You will be draining towards 60% of capacity which will in a cyclic use shorten its life span. I would suggest either a standby charger to kick in at 12v or double battery size.
Also might need to check your particular battery, how fast will it charge off the solar controller/charger. If its drained that much it may take longer than you have sunlight to actually recharge. Each battery has a limit on how fast it will recharge.

All this goes out the window if you do a timed flood/drain. Or have the lower load.

mattyry

Privatteer,
yep Diodes will be installed.
still have not purchased the pump yet so I still have the option of timed flood and drain. Plus with the advantage of timed starts i can cut down on the amount of times i run the pump during the night. The good thing about solar is that you can add another panel or battery if you need to. will have to make sure solar charger, and cables can handle extra current so that if i have to add a panel nothing else need up grading.
might be a good idea to add the change over switch for safe measure.
From what I've read in regards to AGM batteries is they can recover a lot better that lead acid batteries therefore you can discharge down below 50 % (say down to 30% with out affecting the life of the battery). I wouldn't actually know because I don't have first hand experience. you know anything about them?

regards
Matt

Privatteer

Yes AGM supposed to be better than lead acid or gell cell for cyclic use.
There are two "styles" of AGM as well. Standard and those rated for deep cycle use. The deep cycle have thicker plates therefore are heavier.
Here is a graph I saved at some point. Both batteries are AGM but the 2nd was rated for deep cycle and more expensive.

However with both you can see if you discharge to 50% you get 450-650 days lifecycle.
At 30% discharge the lifecycle is about 1300-1550. As an comparison a gel cell sealed spec sheet I have here claims 300 cycles at 30%.
Over the long term only discharging to 25-30% will save you a little money by extending battery life.
Remember also you are going to have days when you get almost no sun at all.

Whatever battery you have should have a similar chart with it or online.

Most of my experience is with standby use for alarms etc. But I have done a few solar setups as well.

Aquastud

The battery I used in my system is 105AH and cost $320.00, the charger cost $275.00. The charge time for a 100AH battery to 80% of charge is 12 hours for my charger. I would definitely suggest timed pump running, and remember the solar cells have got to be able to run pump and charge battery at same time. I still think a week of rainy weather will cause the system to fail, unless you have factored this in with battery capacity and charge time?

mattyry

Thanks for the input guys,

Privatteer, yep definitely a deep cycle AGM. Thanks for the charts.

Aquastud, your comment in regards to the time it takes to charge a battery to 80%. Is that from 50% to 80% ?? How many amps is your charger and is it ran from a 240v supply or solar?? Also what type of battery are you using??

I'm hoping to get my power consumption down to 15w per hour, I have found a pump that runs at 80w & pumps my required water + 300l extra in 12 mins, If my maths is right it = 16wh, My air pump runs at 3.5w which brings me up to 19.5wh
19.5 / 12v = 1.625amps
1.625A X 24 = 39 ah required per day, If i was to cut say 3 cycles down during the night I should squeeze down to 35ah,
If i safely have 70ah in my battery, should give me a couple of day :shifty:

Where I'm working at the moment are currently replacing there deep cycle batteries for there UPS, might see if I can get my hand on a spare battery
have to keep my eyes open for some different pumps
No guarantee my maths is right as well, did in school a while back :shifty:

regards
Matt

Privatteer

I did forget the current draw from the pump during charging too so I think the solar side could be about 10Ah under rated during winter. Suck it and see I guess.

Your (Aquastud) battery is an AGM as well but the ctek charger is at a guess 7 amp at that price?

AGM will charge to 90% extremely fast if you can supply the current. You have to be actually careful your charger is current limited as AGM's are capable of sinking a huge amount of amps when discharged.
Its the last 10% to the absorption level that takes a long time.

Actually I just ran through 25watts on a standalone system on http://www.energymatters.com.au
Probably a bit more accurate since its uses a illumination value.
5 × 85Watt and 200Ah battery was the result for where I am.

Privatteer

Btw I'm not trying to discourage the solar idea. I have a 1.8Kw gridfed system myself.
Just trying to avoid you killing $350 dollar batteries and wondering why :think:

mattyry

Privatteer,
I don't particularly want to deliberately discharge my battery to 30% all the time, so that in a years time it dead, but I just want to factor in to see how much time I have up my sleeve.
I still have the option of running it to 1 GB and only needing 8w per hour which should give me a fair bit of time up my sleeve in regards to my 100ah battery, or I could simply use it as a traditional back up and only turn on when the power has failed. That the beauty about discussing thing over with like minded people who have experience on these subjects.

Hopefully I can get hold of the 150ah battery at work.
Regards
Matt

mattyry

Had a yak to the person that is responsible for the batteries at work. Now im the owner of at least 1 150ah gel battery. might be able to get hold of another

regards

Matt

Aquastud

mattyry wrote:

Aquastud, your comment in regards to the time it takes to charge a battery to 80%. Is that from 50% to 80% ?? How many amps is your charger and is it ran from a 240v supply or solar?? Also what type of battery are you using??

I assume in the manual it means from a discharged state(down to 10.5 volts) which would be the full AH rating of battery. My charger is a multi phase charger with a maximum current of 7A, it can charge batteries from 14 -225AH and is run from 240volt supply.

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Mattyry you seem to be calculating your pump power draw from battery wrong. A batteries AH rating is calculated on the current it can supply for 20 hours down to 10.5 volt, my battery is 105AH and can supply 5.25A for 20 hours (5.25 x 20 = 105), so from this you can calculate your amp draw from battery and how long it will last for. In regards to pump power ( I assume your using 240v pump through inverter) you need to convert it to DC amps, you can work this out approximately by using the electrical formula I(amps) = P(watts) divided by E(volts), I say approximately because there are inverter and pump power factor losses. I have tested the amp draw from battery running a 24watt pump and it was 2.8A, where calculated = 2A. Power factor of pump can be corrected with capacitors and would be worth while in your system. To work out how long the 24watt pump would run for off my system I divide 5.25 by 2.8 =1.875 x 20 = 37.5 hours run time, now if I only run pump 15 minutes per hour, the battery should last for 112.5 hours.

francois

mattyry
i like what you are doing
that is the next thing i want to do with my system
run it using the tools of nature
keep it up
i will follow your progres
good luck

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