New to solar (Geyser and pool pump)

[Rolo]

Hi All

As most of the posts in this new member part, I am also looking at my first solar setup.

I have identified the pool pump (+- 36 000l) as one of the main contributors. Only running the 1,1kW pump for about 7 hours a day (7.7 kw/h). I have found that Bundu pumps have what looks like the solution with a 370W pump and 2 255w panels. My question is if anyone has gone solar pump for the pool or is panels with correct invertor  a better solution. I am looking at adding pipes (water heating) on the roof later on. 

 

With regards to the geyser, it looks like a whole new can of worms all together. I think 200l low pressure system will do the trick. I have no mixer taps in the showers (2 showers devided by same wall). The municipality pressure in Middelburg MP is quite high. I have been told that a reducer valve on the cold water entering the house will solve the pressure differential problem. Also learned that "The Sun Pays" has a system that allows the cold water to run from the fill up tank (5l and 7bar) at the top so the hot and cold would be at same pressure.

 

We don't require very high pressure in the shower, but would at least like the water to be hot and not only lukewarm due to high cold water pressure. We are already "timing" the geyser running time by hand, one hour to one and a half hours (+- 6kW/h)

 

Any suggestions or advice would be much appreciated.

thanks 

[Guest]

Hi Rolo, welcome.

Depending on regulations where you are, Munic or Eskom you supplier, you could look at say a Solis grid tied inverter to power the entire house, pump and geyser. 

Grid tied is much cheaper by a large margin, using the existing pump, geyser etc.

If you want to power it all when Eskom is off, that dictates a different inverter solution. Is that something you would want?

Or if Eskom is off, to just feed very specific circuits like lights, TV etc?

[gallderhen]

With regards to the geyser,

About 6 months ago, I installed an evacuated-tubes split-system solar geyser in our house. The tubes sit outside on the roof, one pipe goes from the geyser to a 12v pump, from the pump it goes up to the roof into the tubes-system, and from the tubes it goes back to the geyser (how the guy explained it to me). Also on the roof is a small 12v solar panel. So what happens is, when the 12v solar panel gets  enough sun light, it powers the pump that pumps the water from the geyser into the tubes sitting ontop of the roof. The tubes warm up the water by transferring the heat they captured from the sun, to the water, and the warm water goes back into the geyser.

 

This summer I've seen the geyser hit temperatures of 80C (before we let out some water as to not trigger the pressure valve installed), and during winter it goes up to about 65 maybe 70. In winter, we have to use the element from 4am to 6am if we want to shower in the morning, but during summer we hardly use the element at all. With regards to savings, our electricity bill has dropped from 30-35KWh per day, to 15-20KWh. I'm figuring the system will pay for itself in 4-6 years.

 

We went with a split system (where the geyser is inside the house) because we get some heavy hail storms in our area, so if the hail does come down on us, tubes will be the only parts that would need replacing.

 

Hope this helps

 

-G-

[Rolo]

Thanks for the advise. I was also looking at something Hybrid for the geyser as I believe mine is still ok.

 

With regards to going off grid, I have prepaid electricity from municipality. As mentioned we run the Geyser for max 1h30 mins a day. Our total consumption is about 15 to 20 units a day. So I figured that the pool and the geyser will be the most gained for $$ spend (R25-R30k in total). Not really looking at powering when Eskom is off, more a cost saving aim in the long run. 90% of lights are LED already.

[Guest]

11 minutes ago, Rolo said:

Not really looking at powering when Eskom is off, more a cost saving aim in the long run.

Then grid tied with say a Solis inverter and as many panels as you can fit to cover the pump and geyser, and all other daytime loads.

Yes, EV tubes are better, but if you have not spent the monies yet, there is a case to be made to get more panels, than spending on EV tubes. Heatpump also an option to use with a grid tied system, if you want.

After the above, the next level is to target the loads that are on when everyone is asleep at night. You should be on <100w per hour for like fridge/freezer, outside lights, alarm system etc.

[Rolo]

Can one expand on such a system as time goes? As far as I understand (and that is not very far) the main thing and most expensive is the inverter. So for lets say running the pool for 7hours and then geyser for 2hours during daylight (about 3 to 4 kw running power). What is the power consumption of the 1,1kW pool pump on startup? 3,5kW?

Don't really want to stack a lot of batteries in the house (only getting married end of Feb but don't think the wife to be would appreciate all the batteries)

@The Terrible Triplett, do you have a cost estimate for doing that? I have about 7mx4m of usable north facing pitched tiled roof.

[LMthethwa]

Hi Rolo,

I am currently running a 1100W pool pump between 5-7 hours, a 1170W Heat pump (plus all house small loads lights, tvs, Dstvs, alarm, wifi.....) using a 4000W  inverter with 9 x 330W panels (Hybrid configuration) (8 x 12 V @ 110h batteries).

• I have reduced my utility  daily utilization from 30-37 KWh to an average of between 12-14 KWh.
• I did not change my pool pump, I just changed the time when its running, the same with the heat pump.
• While my ultimate aim is to go with evacuated tubes, for now while I have the excess power from the panels it just made sense to connect it to the backup.
• The only concern is remembering to switch the Heat pump off in case of after hours load shedding.

I am also new to solar (1 month) and still figuring out a few things with the help from this forum. My advise to you if cash is tight would be:

1) Don't change the pool pump
2) Spend extra on panels and inverter
3) Try and over spec your system, once the bug bites you will regret not putting a buffer of capacity in your initial design.

4) If time is not an issue, try and go in stages and break down your final system design in stages eg. Backup system first, solar panels next, this helped me understand my system in small chunks of information.

I did make a R18 000 mistake with my batteries on my backup by not cycling them enough but.....education is not cheap....except in www.powerforum.co.za

Most importantly do your homework it helps when you have a clue what you want otherwise people sell you all sort of junk and you end up not getting what you expected.

 

[Rolo]

That sounds good. 

Can one add batteries as more backup is required? By not cycling enough, do you meen they are going through full and empty cycles often enough?

 

[Guest]

53 minutes ago, Rolo said:

@The Terrible Triplett, do you have a cost estimate for doing that? I have about 7mx4m of usable north facing pitched tiled roof.

Off the top of my head, you need the Current Transformer and a Solis inverter: https://thepowerstore.co.za/collections/inverters/solis?grid_list=grid-view

Done.

Then some frames, some panels and wires. 

Depending on which model you buy, and check your local municipal regulations for going grid tied, for connecting any inverter for that matter, to your DB board, you add the panels you need.

The ONLY caveat, if Eskom is off, your grid tied inverter is also off. Understand this.

So how it works, lets say you have 4kw of panels on the roof, it is a good day, you get 3.5kw between 10am and 2pm, the pool pump and geyser is on, total of wot, 1.1 + 3.5kw = 3.6kw, then the grid tied inverter will take all it can from the panels, say 3.5kw, send it via the DB board to the pool pump and geyser, drawing 100w from Eskom, as the load is say 3.6kw and the panels can produce, at that time 3.5kw. 

Now from that bare bones explanation, you are now thinking, hold on, let me first heat the geyser, and then start the pump. And the games begin. :-)

Yes, you can apparently have up to 3 Solis grid tied inverters per DB board.

Now, the moment you start talking batteries, the entire game changes, price goes up and it gets more complicated. 

Do you want to talk about batteries?

[Guest]

3 minutes ago, The Terrible Triplett said:

... you get 3.5kw between 10am and 2pm, ...

O less I forget.

From the first moment the panels can produce any watts in the mornings, till the last watt before the sun sets, all those watts are fed into the house, giving you savings on your Eskom bill every single day.

[LMthethwa]

Rolo, Batteries in my view are the most delicate part of the system and require much more attention. Mistakes with batteries are generally irreversible and costly.

1) Yes cycling refers to exactly your understand.

2) As a general rule "not sure where's the rule book", you do not mix old and new batteries and therefore getting the right capacity from start is ideal.

Only when you are ready to replace your old batteries, a few years down the line, should you be able to add without worries.

[Rolo]

So in short, rather look at a panel and inverter setup than changing pool pump and geyser? Don't mind if it will be a bit more expensive as long as the saving over period would greatly improve. 

[phil.g00]

@Rolo,

I like to throw a couple of things into the mix.

(Which you can choose to ignore, but you should not make decisions in ignorance of these things).

1. Legal PV capacity constraints:

As soon as you tie into the grid there are standards and professional  fees and capacities imposed on your electrical PV system.

2. The discussion so far about your pool pump, has served to highlight some merit of having a longer solar day. That is to say, another approach to your panels' orientation could be two banks with the emphasis on production on morning and afternoon respectively.

With regards to 1. ,  I believe a solar thermal geyser is an efficiency winner, but it also has the added bonus's of not imposing on your on legal PV capacity allowance and not requiring expensive sign offs. ( BTW I'd suggest retrofitting tubes to existing geyser).

One could also make the same case for having dedicated pool pump electrical off grid island. Others would argue that that's not as flexible, but I'd counter that if that island is balanced generation vs the load, where is the flexibility needed? This is where 2. comes into it, dedicated panels, but arranged some east, some west to get you a longer, ( but smaller) production throughout the day so that you have as big a peak of power that you can't use around midday. If you have a known constant base load, this is a good marriage.

Just something to think about, before you involve some significant costs for sign-offs and all the red tape.

Or alternatively, it means you don't have to break the law just yet.

Edited January 10, 2019 by phil.g00

[Guest]

Adding to your thoughts @phil.g00 on going EV tubes for geysers makes even more sense if one lives in like CPT, with winter rainfall i.e. low irradiation and clouds to boot. EV tubes preform much better then than any PV system.

On a dedicated PV system for a pool pump, absolutely do-able, I just found the cost of taking a pool pump (we had a 1.1kw one) off grid, to be quite expensive. And a off-the-shelf pool pump is much cheaper to repair/replace than a solar one. Therein the thought that it is cheaper to go with a Solis, grid tied, sorting both out in one go.

Reason is that if you can shave off 80-90% of the pool pump and geyser during the day, say a 2kw element, long term you are better off ito savings, than splitting the systems off.

That is where I'm coming from.

 

[phil.g00]

@The Terrible Triplett

I just bought a pump, (well 3 actually), from different Chinese vendors. 

The difference being that these were submersible borehole pumps. Initially, I bought one to get a feel for the quality, I was impressed with the build.

So on came two more, (210W -80m) one the same and one with a different head. (60m)

Now, I want to stress, none of these pumps have been used yet, but I did see what looked like a re-badge of what I bought, on an SA website for, and I can't remember exactly but  for around R 15-17K in price.

I paid well less than 300 Euro, including the 50 Euro vat and import taxes/pump.

Anyway the nice thing about these pumps is the models I bought (not all the models though) have a built in MPPT. 

Straight on the panels, no inverter, no MPPT required, if it works you cant beat that value with a stick.

So based purely, on the construction of an entirely different pump model ( but from the same vendor), that as yet hasn't been switched on, I would consider getting this for your pool-size:

https://tinyurl.com/y8g34dba

I'll probably be in SA the end of March, and I hope to get at least one borehole pump commissioned then, if there are no issues after a few months, I will be getting this pool pump's big brother.

Edited January 10, 2019 by phil.g00

[Guest]

7 minutes ago, phil.g00 said:

... if it works you cant beat that value with a stick.

There is one way to beat that value ... back-fill the pool. 

 

That is what we ended up doing. Pool costing a fortune and not used and we needed to get rid of a ton of soil.

See, previous owners installed the pool. Lovely.

But we had a cracking wall at the back of the property, the one in the braai room. So we had to get the soil away from it as it is pushing the wall over, the wall not being a retainer wall and all.

Imagine our surprise when all the soil behind the wall back-filled the pool to the brim. ;-)

[Gabriel_2018]

15 minutes ago, phil.g00 said:

@The Terrible Triplett

I just bought a pump, (well 3 actually), from different Chinese vendors. 

The difference being that these were submersible borehole pumps. Initially, I bought one to get a feel for the quality, I was impressed with the build.

So on came two more, (210W -80m) one the same and one with a different head. (60m)

Now, I want to stress, none of these pumps have been used yet, but I did see what looked like a re-badge of what I bought, on an SA website for, and I can't remember exactly but  for around R 15-17K in price.

I paid well less than 300 Euro, including the 50 Euro vat and import taxes/pump.

Anyway the nice thing about these pumps is the models I bought (not all the models though) have a built in MPPT. 

Straight on the panels, no inverter, no MPPT required, if it works you cant beat that value with a stick.

So based purely, on the construction of an entirely different pump model ( but from the same vendor), that as yet hasn't been switched on, I would consider getting this for your pool-size:

https://tinyurl.com/y8g34dba

I'll probably be in SA the end of March, and I hope to get at least one borehole pump commissioned then, if there are no issues after a few months, I will be getting this pool pump's big brother.

Where is the controller? I have one, but it has an external controller.

[Rolo]

13 minutes ago, The Terrible Triplett said:

Imagine our surprise when all the soil behind the wall back-filled the pool to the brim.

HAHAHA, glad you could solve both the problems. But between me and the chocolate Lab that will never happen. Maybe heating the pool water is the only other thing that will happen to it

[phil.g00]

@Javi Martínez

The MPPT is internal to the pump.

They have models with an external controller that are a bit more, I just thought for convenience I'd try it.

Two wires and drop it down the hole.

Its a 200W pump, the dry-hole protection is also supposedly built in.

I just want a constant small flow and don't really want to bother with tank levels or dry hole protection, the idea is that the mains borehole pump (which has all that) works less.

This particular property has 4 boreholes, 3 are not all that strong, but they'll easily do a slow tap, and with normal usage I wont start a flood if the tanks are full.

They supply a spare impeller with the pump, so I suppose even the manufacturer's think it's going to work for a while - we'll see.

I'll just like to add that the intention is that 2 of the boreholes will be off-grid islands mainly because of the additional cost saving of cabling as well.

So if can save on a MPPT, a battery, cabling, control circuitry and an inverter in this application an off-grid island is very persuasive.

 

[Lionheart]

Have you thought about a variable speed/flow pump? I installed one. Initially had a 1.1kw (1.6kw input) now average between 260 and 450 watt depending on how dirty the filter gets. They are expensive but worth it. 

[DeepBass9]

Also measure that power that the pump draws. It is not neccessarily pulling 1.1 kw. I have an 800w pump that pulls about 600W with the kreepy connected and 450W without the creepy. Check for flow constrictions and suchlike that cause the pump to work harder. Be efficient first before you spend a lot of money powering your inefficiency.

Maybe everyone knows this, but it takes less power to push water slowly through a big pipe thank quickly through a small pipe, for the same volume moved.. Especially if you have bends that cause turbulent flow which causes more resistance.

Edited January 10, 2019 by DeepBass9

[phil.g00]

I stand to be corrected isn't the rule of thumb to cycle the pool's full volume daily?

(Not my area)

But whatever it is that has to happen, doing it slowly, through the thickest pipes etc, getting rid of all the inefficiencies, still means there is X amount of h20  to shift, and there no getting away from that.

Doing it with smaller just means longer.

Unless you're cutting down on what actually needs to get done.

That's why I actually intend to go bigger, and get it all done while the sun is shining.

[Gabriel_2018]

16 hours ago, Lionheart said:

Have you thought about a variable speed/flow pump? I installed one. Initially had a 1.1kw (1.6kw input) now average between 260 and 450 watt depending on how dirty the filter gets. They are expensive but worth it. 

I think it is not the best choice. You have to consider that a small asynchronus induction motor has low efficiency, tipycally 55-60 % and has a rpm limit. On the other side, DC pumps  we are talking about, are PMSM, permanent magnet sychronus motor, which has a higher efficiency, tipycally 80-90%, and can work in a wide range of rpm.

[Rolo]

Thanks for all the pointers and thoughts. 

On the pool side. Saw that it is recommended to turn the total volume of the pool at least twice a day. So the solar pump I am interested in does it in 6 hours (being 36000 l pool). As I am looking at different ways to heat the water as well, I would much rather turn it slowly and for long time as it should heat up more in the heat system (currently just coiled up 25mm black pipe). 

 

On the geyser side, after reading more on the regulations regarding grid tied I actually think that thermosiphon will be the route. But again I can't decide between a split system using a collecting manifold and old geyser with 12v circulation pump or using a complete new system and geyser. I am very interested in using the Geyserwise controller regardless of system.

[Guest]

1 hour ago, Rolo said:

But again I can't decide between a split system using a collecting manifold and old geyser with 12v circulation pump or using a complete new system and geyser.

I may misread this, but if not, EV tubes are split. tubes on the roof, geysers wherever you have it? As mentioned before, an idea to save costs is to retrofit the system i.e. keep your old geyser till it pops and then get a proper one with the insurance payout. Geysers pop every +-5 years. 

1 hour ago, Rolo said:

I would much rather turn it slowly and for long time as it should heat up more in the heat system (currently just coiled up 25mm black pipe). 

More clever people than me can add more in-depth knowledge but what I gleaned yonks ago from other clever people when I wanted to do it is that it makes no difference how fast the water goes via the 25mm pipes, bar the pressure.

Pumping slow or fast, same amount of heat is transferred over time.

So KIS (keep it simple) and let it run normally.