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Posted

It's time to fill up my pool for summer (so my kids tell me), and I would like to controll when the pool pump runs in a sensible manner. Because I am off grid, I don't want the pool pump draining batteries on cloudy days. Obviously I will put the pool pump on a timer so it runs from 9am to 3pm, but I would like the pump to switch off if it becomes cloudy. Is there a switch that will do that,,or is something more complicated required? 

Posted
6 minutes ago, TinkerBoy said:

Chris how do you use the relay. Do you not end up with the same problem as using the voltage to switch between modes on the Axpert ? If something pulls a big load the you will switch off and the on again when its gone.

I run a geyser so switching is not a problem. Switch on at 53.5V switch off at 51.90V. One could schedule it to switch on deeper into absorb. With my settings switch on during bulk is at about 10am and there is enough power to power batteries and the geyser. If there is a large load and one starts to draw from the battery within a minute the battery voltage drops below 52V. There needs to be quite strong sunshine for it to recover to 53.5V. I have found battery voltage to be a good proxy for the availability of excess energy. You can program in a time delay if you are worried about frequent switching. But for a resistive load it is not something I am too concerned about. The problem with a lux meter you still need additional information in terms of what your load is. AICC gives this to you but for R120 the relay fits my bill. It is not perfect but I fear one ends up throwing a lot of money to make a R10/day saving.

Posted

Other than setting up a remote switch I cannot see how you could achieve this. The problem I foresee is that there is too much variables that you would need to contend with. Is the clouds momentary or the whole day extr. I have some loads that I run when the batts is fully charged and the weather is fine and basicly I keep an eye on the soc and solar output. If all looks well I phone the relay and it switches on. (Using the Arduino code that I posted here on the forum) If things does not look lekker if switch if off again.

Posted
15 minutes ago, DeepBass9 said:

It's a pool pump, so nothing critical. Maybe it's as say as getting a day night switch and placing t in the right place to only switch in bright sunlight?

You could also paint/cover the day night so that a limited amount of sunlight comes through. Failing that if you use a LDR with a Arduino you can calibrate the "switch" so that it only switches on at a certain sunlight level.... 

Posted
1 hour ago, Chris Hobson said:

I fear one ends up throwing a lot of money to make a R10/day saving.

+1 - also tried to get a pool pump to only work under optimal light conditions without too many parts.

 

Am now trying to figure how to solve my situation where whilst the batts are being charged in the mornings, I KNOW there is more than enough power to power the main daily load with the batts only fully charged at 1ish the afternoon. Doing it manually as Paul at present, just no devices involved.

On automated I need to wait for the SOC to be reached before main daily load switches back to solar at about 10-11ish for the rest of the day, as I am now powering more stuff off-grid 24/7, I need the batts charged as a priority. So if clouds appear during the day, main load must go back to Eskom to favour battery charging. EDIT: Currently SOC is used to go back to Eskom, so that is sorted, it is just the flip side I need to figure.

So same as the pool pump, it all ties back to max panel input at a specific time for a specific period. I know there are other easier solutions, at a price, the thing is my system is "mechanical" so it needs no attention whatsoever nor software to run bar a BMV and it's relay.

Posted
3 hours ago, Chris Hobson said:

I fear one ends up throwing a lot of money to make a R10/day saving.

Its not for the saving, it is so you don't have an unexpected cloudy day which kills your batteries by circulating water in the pool. Not as complicated a problem as TTTs as I am off grid and the energy used will be 'excess'. I'm going to get another 3x300W panels to drive the pool pump over summer, so next winter I should have ample power from the larger array, as I will likely drain the pool at the end of swimming season.

Posted

Jip, those are what I was referring to when I said "... at a price". Must admit, IF I was to ever put a pool in again, part of the installation cost would be a pump with just panels.

Posted

I had a daylight switch that I modified to work in reverse: Switch on during the day. Well.... I still have that daylight switch but my plan didn't work. This is not to say that it cannot be done with any other daylight switch, just that it didn't work with mine.

The problem was that the daylight switch had a design fault right from the start, one that I discovered during load shedding. If the power went out AFTER dark, it would not always come back on afterwards. I think there was some kind of hysteresis circuit in it that malfunctioned.

Anyway, so after the modification, the design flaw caused the same problem at daybreak. It would work fine during testing (sudden changes in light level cause by yourself) but the gradual increase in light levels at daybreak failed to turn it on.

I've been meaning to figure the problem out -- it has to be a RC (capacitor + resistor) combo somewhere -- but just haven't gotten round to it.

With that said however... it might work with other daylight switches. When I looked at the circuit, what they do essentially is have a LDR wired in a voltage divider chain, pulling the base of a NPN transistor down when it is light. When it gets dark, the resistance of the LDR rises (from about 1k during the day to 100k at night) and the base of the transistor is pulled up. This is fed into a second transistor (Darlington setup basically) and that switches a relay.

So my modification simply swapped the divider chain around, placing the LDR on the high side so it pulls the voltage up during the day, allowing the other resistor in the chain to pull it down at night. It's not as simply as just swapping the components, you have to carefully calculate the bias voltage and ensure you're not killing the transistor. Nevertheless, I got it working... on the bench. So if you like messing with this sort of thing, that might be something to try :-)

Posted
59 minutes ago, DeepBass9 said:

I was thinking of using a relay, just swappjngnthe NO and NC around.

Aaaah yes, I was wondering why I went the long way round... I remember now. My unit didn't have a NC contact :-)

  • 3 months later...
Posted

Pondering this problem again since I now have a full pool and enough power for the pool pump.

Latest idea is an adjustable day night sensor in a black box so it only gets light when the sun is high enough, and adjustable so that if it clouds over it switches off. I may need a relay and change the NC to NO.

I'll give it a try at the weekend, should work with a bit of tweaking.....

 dn.jpg

 

Posted
On 1/20/2017 at 11:03 AM, DeepBass9 said:

Pondering this problem again since I now have a full pool and enough power for the pool pump.

Latest idea is an adjustable day night sensor in a black box so it only gets light when the sun is high enough, and adjustable so that if it clouds over it switches off. I may need a relay and change the NC to NO.

I'll give it a try at the weekend, should work with a bit of tweaking.....

 dn.jpg

 

That could work but I'm not sure if the type you buy at Builder's will work. You might possibly need to shade it slightly since it's probably not going to change enough to work in cloudy conditions. 

Posted
It's time to fill up my pool for summer (so my kids tell me), and I would like to controll when the pool pump runs in a sensible manner. Because I am off grid, I don't want the pool pump draining batteries on cloudy days. Obviously I will put the pool pump on a timer so it runs from 9am to 3pm, but I would like the pump to switch off if it becomes cloudy. Is there a switch that will do that,,or is something more complicated required? 



What i would have done is to use a raspberry pi with a lux sensor and work on avg lux over a selectable period to avoid switching on and off all over the place.

It can be custom set. Like avg of 5 min or 30 min ect . If avg below the sepoint the swich off and above the setpoint then pull the contract and start the pump



Sent from my SM-G920F using Tapatalk

  • 7 months later...
Posted

I had my inverter running off a daylight switch  and a contactor at one time and if worked very well  . I got it from builders ,the 25 amp adjustable one   and yes I considered putting one on the pool but at  the time I had another set up going .  son I cant see it not working

cheers

ps if you don't have it right yet I have another kiss (keep it super simple )solution

  • 3 weeks later...
Posted

@DeepBass9 I  bought a R200 probe/sensor(variable) normally used for an incubator.That was connected to my irrigation transformer (16v) which fed a solenoid on the valve

I used which rerouted my pool water on to my roof on sunny days or when the temperature was warm(adjustable) enough for pool heating.

 

 

  • 5 years later...

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