Pool pump on inverter

[Louw]

I am trying to get my pool pump to run from my solar. It is a stock standard 750W pump on a 2KW Chinese inverter.

The issue is that the inverter can't handle the spike to start the pump. I am not sure if it is the inverter itself (which should be able to handle a 4kw spike) or if the surge in power requirements, increase the draw from the batteries (3kw surge = 125 Amps). I think it might be the second one as my MPPT also reset when I try it, so I think the surge causes a drop in voltage, resulting in the disconnect of both the Inverter and MPPT.

Any suggestions on what i can do? I am thinking about getting a 24V Axpert 3KVA. Will this help as the spike could be covered from Eskom, changing back to Solar after the spike  (Would prefer a Blue Inverter but can't afford it at the moment and when I go that route I want to upgrade to 48V, requiring more/new batteries.)

I installing a borehole in the next 2 weeks which will add 2 pumps of around 1.1KW each. So I am hoping to be able to run the 3 pumps through the day from solar but currently i am struggling with 1!

[___]

42 minutes ago, Louw said:

think it might be the second one as my MPPT also reset when I try it,

I concur. So the obvious solution is to get better batteries? What have you got now?

If you're talking 125 ampere, you might not be able to use a 100Ah battery. Of course car batteries routinely do this sort of thing, where a 80Ah battery might have cold cranking amps of 500A or more, but they are designed for that sort of thing and compromise on cycle life because of that.

You could also look at different chemistries, for example an AGM battery will allow higher peak currents than a flooded deep cycle.

You could try messing with super capacitors to bridge the gap, which to me feels like a "hack" or rather a "kludge", to use computing terminology.

Or you could look at using a soft-starter of some kind with the pump: Basically a device that ramps up the voltage in a specific fashion, usually to reduce the mechanical stress on the physical components, but it also helps a little with the current draw.

In other news, after looking into soft starters I finally understand the big electrical motor we had in the workshop in high school that had a Start and a Run setting. It literally wired the windings in series for a softer lower-torque start, and then switched them into parallel for speed and power. That was single phase. Of course with three phase it gets even more interesting. Off topic, I know :-)

[___]

58 minutes ago, Louw said:

I am thinking about getting a 24V Axpert 3KVA. Will this help as the spike could be covered from Eskom

Forgot to respond to this: The inverter might not be able to switch quickly enough. I don't know how long the Axpert takes to switch. The better Victron equipment can switch sub-second, and then it would work. The inverter I have (an older Multiplus Compact) takes up to ten seconds to switch, so it will just fall over. Even if the inverter does switch within a second, if your DC voltage is pulled down too low in that second it will still fall over due to under-volt.

Another solution might be to start the pump while in bypass and switch back to solar afterwards, but that will require manual intervention or a clever control system.

One more solution: Get a real hybrid, so it just takes the difference from the grid. That would mean getting an infinisolar, which is probably not an option given the price -- even if it is the cheapest of the lot -- and your plans to go blue later.

Re blue: Have it from the horses mouth that what TTT was hoping for (that the Chinese boys will put pressure on prices) is actually transpiring. Now if we can just fix our economy and get the currency back in line, there is possibly a bright blue future in all this.

[Guest]

11 minutes ago, plonkster said:

that the Chinese boys will put pressure on prices

Good.

@Louw from my attempts on a 1.1kw pool pump and solar I can say have a look at Grundfos solar pumps.

[DeepBass9]

But Grundfos solar pumps cost as much as a good inverter (R20k+) and are really designed for remote locations. If you are spending the money, and the borehole and pool is close to your house anyway, rather buy a decent inverter and then you can use normal 220V kit.

[Louw]

@plonkster I have T105 so 225Ah in Total.  

From my limited research I am seeing more and more specials on Victron's. Hopefully the rand can keep stable at low R13's allowing me to buy one at a reasonable price. First need to sort out the water for the Garden.  At R200/kl on Level 3 Water restrictions it seems to be a good investment (even after paying Eskom for powering the pumps)

@The Terrible Triplett @ R23k just for the pump vs R5k for a 220V pump I am not sure it is a good deal. Would then rather spend the money on a Victron inveter/more batteries

[___]

Just now, Louw said:

 I have T105 so 225Ah in Total.  

My 1.6kva Victron on a 24V T125 bank (245Ah) would start my well-point pump like it was nothing (850w motor). Something doesn't sound right, you sure those batteries are still okay?

 

2 minutes ago, Louw said:

At R200/kl on Level 3 Water restrictions

WHAT!? Where is that? I know Cape Town is around R80/kl in the top bracket. Since my sprinkler system runs at 4kl/hour, even 15 minutes amounts to R80/day for watering the garden... so running the pump from Eskom power, even for an hour (< R2) is a complete no-brainer.

[Guest]

1 minute ago, Louw said:

@ R23k just for the pump vs R5k for a 220V pump I am not sure it is a good deal. Would then rather spend the money on a Victron inveter/more batteries

Jip I ran into the same issue. So I tried very hard to use normal pumps that you buy at the local shop, but their startup currents, eina.

It becomes a balancing act, expensive pump or large Kw/VA capable inverter to handle the startup, and then you have to go 48v.

[Louw]

I am thinking that the issue might be with the pump. When I bought the house there was a pump installed. I tested it once on the solar and it ran fine. The bearings went and the whole pump was a right off. The new pump does not want to start on the solar. I am going to check what will happen if I replace the capacitor.

When CPT (Not if) goes to Level 3 restrictions water will be R200.16 Inc VAT for usage above 50Kl/month

 

 

[Guest]

Just now, Louw said:

When CPT (Not if) goes to Level 3 restrictions water will be R200.16 Inc VAT for usage above 50Kl/month

Do you have more info? Think it is coming?

[Louw]

The pricing is from CPT website.

Taking into account that the dams are at 61.8% vs 74.2% same time last year it is a question of time before we go to Level 3

[___]

I need to put up a tank. My well can only deliver around a kiloliter at a time before it runs dry (around 45-50 minutes of pumping), and by April it was running dry after just 12 minutes. Need to pump slower, store, and irrigate at night.

[Louw]

I bought a 4,500lt tank for R3,999 at Makro in last week. Best price i could get.

I run a wellpoint at my Wife's practise. Luckily it is low lying so the water last most of the Summer. Getting around 1,300 lt per hour at 2.5m depth.  In April it started struggling after 45 minutes usage, but luckily my controller allows 3 starting times. So I water half of the garden the one day (40min) with the other half the next day (30min).

Wellpoint cost: R1,500 (Had a pump already)

Water saving in first year: 250kl 

Payback time is calculated in hours!

 

[KLEVA]

Is a 12/24V pump not an option? Dunno if you can get for a pool?

My solar pump and pressure pump for geyser run off a 12V 105Ah (other stuff also runs but very low draw from them) and I use a cheapie 10A Ellies solar charger for them, admittedly they don't draw as much power and for much shorter periods of time.

[KLEVA]

While wellpoints are being discussed, does anyone know if they are an option outside the Western Cape?

[Louw]

@KLEVA It depends more on the soil type than the area.

If you have sandy soil with a clay level less than 8 meters deep it is an option. The water sits in the sand above the clay.

Otherwise you looking at a borehole.  Check on the internet for suppliers. The one I used will tell you in 30 seconds whether it is an option just based on your street address (He has been doing it for 40 years)

 

[DeepBass9]

The 8m is important as the well pump just creates low pressure and the atmosphere pushes the water up. The thoeretical maximum suction depth is 10m odd if your pump can create a complete vacuum! Any deeper than that you need a submersible pump.

[___]

1 hour ago, DeepBass9 said:

The 8m is important as the well pump just creates low pressure and the atmosphere pushes the water up. The thoeretical maximum suction depth is 10m odd if your pump can create a complete vacuum! Any deeper than that you need a submersible pump.

What if the pump is already primed? I have a so-called self-priming centrifugal pump on my well, with a foot-valve at the bottom. I never tried the self-priming though. Installed it in 2011, filled it with a bucket the first time round, and that was that.

[Guest]

On 9/22/2016 at 10:16 AM, Louw said:

When CPT (Not if) goes to Level 3 restrictions

And there it is, as from 1 Nov 2016 ... http://www.capetown.gov.za/en/MediaReleases/Pages/CitysMaycorecommendsimplementationofLevel3waterrestrictions.aspx

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5 minutes ago, The Terrible Triplett said:

And there it is, as from 1 Nov 2016 ... http://www.capetown.gov.za/en/MediaReleases/Pages/CitysMaycorecommendsimplementationofLevel3waterrestrictions.aspx

The only way for me to avoid the increase would be to cut my consumption by more than 50%. Not going to happen.

It's really scary. When I moved in here, levies (plus water, sanitation) was around R750. After this increase, it will be R2000 basically every month. We're talking almost three times the cost in a mere 6 years. Time to seriously consider tanks and stuff.

[Guest]

2 hours ago, plonkster said:

The only way for me to avoid the increase would be to cut my consumption by more than 50%.

We are down to about about 16kl / 552l per day. Still pushing lower for now it becomes feasible to start my next move: Using washing machines water on the grass.

Once all is said and done, that we can say we have all we need and we are as low as we can possibly be, target being <10kl per month, then I will be happy.

[___]

We average around 28kl a month. Technically it's two households. But the other "household" is just a single person renting the flat. So that is mostly the wife doing washing... and you guys know how difficult it is to retrain those guys :-)

[Guest]

43 minutes ago, plonkster said:

We average around 28kl a month. Technically it's two households. But the other "household" is just a single person renting the flat. So that is mostly the wife doing washing... and you guys know how difficult it is to retrain those guys :-)

Same as you Plonk, 2 households. The washing machines, 2 of them, I suspect uses a LOT of water.

FWIW. We used to average 28-30kl a month, we reduced and kept on measuring, reducing more. I could NOT understand how we could be using 1000l per day.

After a couple of months we asked them to move the meter for the muni said they cannot read the meter as we are never home ... I called BS, and told them that. We work from home I said. The 2nd household is a retired couple, I said, own interkom. 

They moved the meter therefor had to install a new one.

Next measurement we dropped to half our average consumption.

If I was you, check your consumption and if you are having doubts, have the meter replaced. 

 

[Louw]

Drilled a borehole in last week. Borehole pump being installed tomorrow. Pressure pump and irrigation going in over the weekend. Then we should be down to 10Kl per month with a jump in electricity usage of around R150 - That is if I water my garden with 3,000lt per day!

[Johandup]

Drilled a borehole in last week. Borehole pump being installed tomorrow. Pressure pump and irrigation going in over the weekend. Then we should be down to 10Kl per month with a jump in electricity usage of around R150 - That is if I water my garden with 3,000lt per day!

Do you intend to use the borehole pump for irrigation?

You need to check the pressures required for the sprays. That will dictate the size of your pump.

I use a separate pump from the jojo tank to irrigate. Am not happy with the setup as it is. Not efficient.

Use easily 15kl per day for watering a big garden.

Got a very strong borehole. Had the water analyzed and am using it for household consumption as well. Much better quality than the municipal water.

No more water supply problems :-)

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