Pond aerator up and running

[Bryan Sloan]

Hello!! Had a lot of fun putting this together and it works well.

Wanted to power a 1.4 amp 75 Watt air pump for my pond. Didn't need it to run 24x7, so I chose a run time of 8 hours per day.

I followed Will's video on how to size a system, factored in 30% oversized arrays to reduce battery cost, and then rounded up.

3x Rich Solar Monocrystalline 200 watt panels
1x Renogy 60A MPPT Charge Controller
2x VMAX SLR125 SLA Batteries
1x GoWISE 600 Watt Pure Sine Wave Power Inverter
1x Hiblow HP 100LL Air Pump

Checking my work on how long the system will run, I get

2 batteries x 12 volts x 125 amp hours / 2 (50% discharge rate for SLA) / 2 (days of autonomy) = 750 watt hours
750 watt hours / 75 watts of usage = 10 hours of run time

Am very happy to confirm I get a full charge every day with my pump timer set to run 8 hours.

Lesson learned #1 - The system ended up beefier than I expected. I started out thinking a 75 watt load was nothing and a single solar panel would do the trick. However, the math taught me different.

Lesson learned #2 - This one took me about 3 days to ponder and then I had to laugh at myself. I measured 6.49 amps between the batteries and the Inverter. My pump is rated at 1.4 amps. Thinking disaster until the answer hit me days later. 6.49 amps at 12v is the same as 1.4 amps at 120v. Sigh........

I have the air pump split to feed two aerators on each end of the pond.

 

[snoobler]

2 * 12 * 125 /2 = 1500Wh (50% of your available capacity)

1500Wh / 75W * .85 (inefficiencies) = 17 hours run

750Wh would need 750Wh/Xh of solar where X depends on your location in link #5 in my signature. 5 is a commonly used number, to 750/5 = 150W of panels. In any case, you have mega-solar available.

At 250Ah of total battery capacity, 25A is your optimal charge current with 32-33 being acceptable as well. 25A * 12V = 300W, so you may be charging your batteries at too high a current UNLESS you use very little capacity overnight, and you're immediately in absorption - thus you're voltage limited and current is reduced. Alternately, you can set a peak charge current in some charge controllers. If you're consistently charging up early in the morning well before you get anything near peak current, it's a non-issue because the solar can't produce that much anyway. The only time it would be an issue is on cloudy days where you have a lot of usage with very little solar - the batteries drain to about 70% and then the clouds part providing maximum solar current of 50A. Most AGM will tolerate that if it's not a daily thing. Consult your battery specs for any published guidelines.

For battery health, I would experiment by taking one of the panels out by bypassing it and see how the system performs.

Lastly, your bracing at the base of the legs has negligible benefit. You've only raised the moment pivot by what looks less than a foot. When you have it adjusted to the winter setting, where it's near vertical, if its subjected to significant winds in excess of 30mph, your 4x4s may break. I would re-brace to the midpoint to cut the bending load in half.

All constructive criticism aside, nice work. Looks good.

 

[Bryan Sloan]

snooble,

Thanks for the review and comments.

In my run time calculation, I used days of autonomy. You didn't include that. Does it not apply to my example, or do you not use it at all ?

Thanks for the inefficiencies reminder. I will add that to my notes.

On the location factor, I get an average of 3.7 in western PA. 750Wh/3.7 = 203W panel. That is amazing. I have noticed my system charges really fast and stays fully charged all day. I run the pump every other hour from 6am to 8pm, nothing runs overnight. I will do more research. What would a high current charge look like on the system. Any immediate recognizable symptoms other than battery degradation over time ? I will try your suggestion and remove one of the panels and see how things go.

Next year, I would like to add a DC water pump for a small greenhouse. I didn't think the system would be oversized by double, but now I'm thinking a greenhouse water pump and some flag pole spot lights.

I added the existing braces because the stand seemed a bit unstable. I will add a higher set.

Appreciate all the info

Bryan

 

[snoobler]

I missed the 2 day autonomy criterion. Sorry about that.

Excessive charge current will decrease cycle life, but it's likely a non-issue. You're barely tickling the batteries overnight, charging quickly and only in the morning, you're not suffering from it.

 

[Bryan Sloan]

Thanks !!

 

[gilboc]

Brian looks great. I'm new to forum. I'm looking to do the same. I have a pond that has a workhorse PSC 200 controller with 800 watt array powering a 75 ft well pump that I use to keep the pond full. I am not utilizing storage batteries because I do not need continuous pumping. I do need to set up an aerator if I am to stock it with fish. Is there anything different you would have done? How deep of a pond are you aerating with the Hiblow 100LL? System looks nice, as said researching different options. Thanks

 

[Bryan Sloan]

gilboc, I went round and round deciding on a ground mount design. My turned out nice with the component shelves, but I do like the looks of yours. Nothing like a clean single pole installation. I wouldn't have done anything different on my system. I run the pump a few hours after dark, and the entire system is working well. It charges very quickly. I do need to disconnect the third panel like snoobler suggested and see if two panels can keep a full charge. The Hiblow pump is awesome. I picked that one because it's only 75w and is mostly maintenance free. A filter cleaning once a year. The hose coming out of the pump is 5/8", and I have that split into two 3/8" hoses to my aerators. The pond is 8-9' deep. It delivers plenty of air.

 

[RobCLaGrange]

Brian this system looks great! This might be exactly what I am looking for! I am looking to do it for a 1.5 acre pond with a deep spot of 15' but don't have to drop it all the way to the bottom so I think the will be the ticket.

I am in La Grange Texas so we get LOTS of sun, I wonder if I should just use 2x250 watt on the panels? Otherwise I would use all the same equipment. Really looking forward to understanding this set of skills and technology, thanks for the help guys!

Snoobler any advise?

Rob

 

[RobCLaGrange]

Brian this system looks great! This might be exactly what I am looking for! I am looking to do it for a 1.5 acre pond with a deep spot of 15' but don't have to drop it all the way to the bottom so I think the will be the ticket.

I am in La Grange Texas so we get LOTS of sun, I wonder if I should just use 2x250 watt on the panels? Otherwise I would use all the same equipment. Really looking forward to understanding this set of skills and technology, thanks for the help guys!

Snoobler any advise?

Rob

That air pump doesn't like to be deeper than 8' so looks like I will need to set it up similar to an "air lift" and put the diffuser in a 4" PVC 5' or so down and pull deeper water up but will still work I think.