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How I started with my small system for loadshedding;


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About a year ago we needed security lighting for our small guesthouse during night-time black-outs.

I went out and bought five 10 amp spotlights(750lm), which I mounted on top of the roof to cover all the areas which needed lighting.(+-50Amps/hr)

Bought an Omega opw-800 Inverter and 2x 80Amp/hr deep-cell batteries with 2x 150 Watt 18volt solar panels in parallel for the 12volt 160Ampere hours.

Bought an osaka charge controller(30amp) for R310.00 to charge the two batteries (pwm).

Built an automatic switch, to switch on the inverter during night-time load shedding(80Amp 12volt relay with normally closed contacts) powered by a 12volt cellphone battery charger. (Just have to remember to switch off in the morning for power-cuts during the day.)

This worked fine until we realized that our guests needed to shower after work and then it got more complicated ! ūüėČ

I had previously installed a 2500litre jojo tank with a 750Watt booster-pump to supply water during shut-offs(they stop the pumps supplying water to town).

Now this 750Watt booster-pump was to big to handle by my 800Watt inverter and would not run it.

Went out to the Hardware store and bought a 270Watt booster-pump and installed.

Bought a 4000Watt pure sine-wave inverter from Takealot (they deliver free of charge to your doorstep)

Edited by phalaborwa
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I realized after a day or two that the two deep solar batteries I had was too small, to handle the load, as one is only supposed to discharge to 50% of total capacity.

Went and bought two 100Amp/hr batteries and placed them in parallel with two older 80Amp/hr batteries.

Purchased a MPPT Controller from takealot(JN-MPPT-MINI 30Amp). The only setting I changed was the over voltage discharge from 10.8 to> 11.9volt.

I find that the charging of batteries are struggling to get to the full state with constant on-off load from the pump and decided that I need to increase the size of the nozzles of our five toilets to enable a faster filling up of the tanks, as it takes about four to six minutes running of the booster pump to fill up a toilet-tank.

Any help/ideas will be much appreciated to improve the efficiency of my system.

 

This is how I connected the four Batteries:

 

 

Balanced parralel connection.jpg

Edited by phalaborwa
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9 hours ago, phalaborwa said:

Went and bought two 100Amp/hr batteries and placed them in parallel with two older 80Amp/hr batteries.

You are reducing the two new 100amp/hr to 80amp/hr in series,  and in this config you cannot keep them separate as @Vassen said. I played around with this kind of home made for some years, this year we only went into solar properly because of eskom. We have debated at length the geyers. I have the Geyserwise system (12K at the time), most people use the solar inverter. So far best solution is gas, do you have good gas supplies in your town look into using a gas setup for geyser. The geyser is just a much bigger kettle really? A gas setup is by far also the most cost effective.

Edited by RyanG
sorry I see not in series, in charging it will only charge to the lowest AMP and the two 100 will draw down to 80
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I think you should strongly consider a water pressure tank in your plumbing setup. Roughly for the cost of one 100Ah battery you could get a 100l tank that keeps pressurized water on standby for multiple toilet flushes and short showers. Re-filling the pressure tank with the booster pump should take less time than you spend filling toilets through a valve, and should help to extend the life of your batteries and pump.

Edited by GreenFields
fact check
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Hi @phalaborwa

The system you have put together there is fine for lighter loads and a few very short term surge loads - At 12v, the losses add up quickly!

But all is not lost - Try and get away from pumping water until it is an emergency - The inverter would be better spent running lighting and small loads, such as tv/sound system etc - the creature comforts that make "no power" bearable.

Instead of pumping water on demand, could you possibly install a header tank (unaware of your roof height and space)  - A small 200 or 500L tank, with a float valve to top it up when water pressure is available, which then gravity feeds your cisterns and showers - If you can get it to about 10m, that equates to around 1 bar of pressure, which will run the lower pressure gas geysers and be more than adequate to fill the toilet cisterns.... 10m sounds a challenge to get a tank to, but there are some easy tricks to doing it, even higher, even alone that barely break a sweat to get it done.... (Takes more effort to dig the holes for the base posts.) Also, if the cisterns are taking a very long time to fill, possibly ream the openings of the float valve a little larger(Or is your piping caked with lime perhaps) - I did this when I installed my grey water flushing system - The orifii were opened from about 2mm to around 5mm dia, as the grey header tank sits at barely 4m altitude - Cistern filling takes little over a minute....

As to running different Ah rated batteries in parallel, I do NOT agree with the previous posters, on the proviso that the chemistry/style of batteries are similar - ie do not mix flooded batteries with AGM etc - if your deep cycles are all flooded cell lead acid, of similar chemistry, they are compatible, the charge/discharge curves are close enough to be similar, and they should cohabit quite cheerfully - One thing that I would recommend, would be the addition of a good old 15A(even an AC one) circuit breaker on the positive pole of each battery before it goes into the main positive buss line - Should a battery short a cell by dropping a plate or for some other reason, the reverse current supplied by the other batteries could amount to enough to cause quite a bit of damage, to say the least. In a perfect world, each battery should have leads the same total length to the buss cable, so allowing each battery to be at as similar a voltage as possible during its charge/discharge process. With dissimilar rated batteries, small over/underages will occur but if you maintain the similar lengths as short as is conveniently possible and the buss cable/bar as large a sectional area as is possible, these over/unders should be relatively negligible....

I no longer have a header tank that I use for potable water, but what I have done, to minimize pump on/off cycling, is to add some really basic air accumulators on the pump output line(referred to above as pressure tanks) - they are simple, work well, and are virtually indestructible. Simply put, take any airtight, corrosion resistant cylinder(Old Stainless Beer keg, Old Ali CO2 extinguisher), invert it, screw in an adequately sized T piece, and plumb it into your pressure line on the outlet of the pressure pump. The idea is to trap an air cushion in there that the water pump pressurizes when it is running - Set your pressures on your pump(if you can) to come on as low as possible and to stop pumping at as high a pressure as is possible - The accumulated pressure in the cylinder will amount to around 50% of pressurized volume, sometimes a bit more, of pressurized feed to the house, before the pump has to kick in again... Not only does this save quite a bit of inverter load (getting the pump moving takes a fair whack), but also lengthens the lifespan of the pump quite considerably in my experience. One could even place these homebrew accumulators at various locations that are convenient along the pipe - I have one 20L unit close to my kitchen and one close to the bathroom on the external walls.... The downside of them is that about every 3 months or so, you will need to turn off the water pressure/pumps and open a tap or valve that is at a lower physical height than the accumulator, to drain any excess water and allow atmospheric air to take it's place (you will notice it is required quite easily, the pump starts more often than it should) - The air does tend to dissolve into the water over time and the trapped air volume tends to decrease... but that is a small inconvenience overall...

As to running your 2kw water element on the inverter - I wouldn't, certainly not on a 12v Inverter and definitely not on the one you have in the picture! (without seeing the exact specs for your unit, if made of chinesium, they are usually rated and labelled at their maximum surge power, not their running average maximum - 4kw surge rated inverters are normally around 2.2 to 2.5kw highest nominal constant load. Even if the inverter is capable of supplying the power, your batteries wont take it for long - to put it in perspective, today, we had some good sun and I shunted about 1.6kw into my "dump load" geyser (gives mildly preheated water to my gas geysers) for around an hour, maybe a bit less.... Water temp in the tank went from 17 to 21.4C .... Its around 250L or so... A better solution for water heating is by using a waste oil fired heat exchanger system, but, like anything, the worse the fuel, the more the maintenance... (I won't get into that here)....

Hope this is of some help...

Cya

E

 

 

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2 hours ago, Vassen said:

I assume you mean 10 watts and not 10 Amps.

Thanx Vassen, that was a slip.

Generally, we are not supposed to add different types of batteries in parallel. Different batteries have different internal resistances, different charged voltages. It will work but it’s not optimal and could result in shortened battery life. 

They are all agms, Vassen.

So I don’t see any type of protection circuitry in your pictures. Battery fuses/ solar protection fuses, DC disconnect, Surge arrestors. Although at 12V it should be safe, you seem to be expanding the system and you will soon end up with a much bigger system without any protection. 12V can still cause fires. 

All protection is on the other side of the wall(I drilled holes through the wall in kitchen)

"you will soon end up with a much bigger system"  Yes I plan to use the old pwm controller with a single panel to feed into the batteries, as they struggle to get fully charged.

Can the inverter run at only 12V or is there an option for 24V? If it’s a 12V only system, as you have connected, 4000W @ 12V, means you are running about 333A through those battery cables at full power. On a 360Ah battery bank, depending on the battery specs, that should be possible. However, you will need about 100mm2 cable assuming 5% losses and a cable length of 1meter. That’s insane. Losses are also a lot more when running at 12V compared to 24V or 48V. If you can run them at 24V, then the current is half. It’s still a lot at 165A, which means you could probably use 35mm2 cable. 

What size cables are you using currently.   I am using car jumper cables at this stage as input to the converter.

Why would you want to do this? You’ve got a 360Ah bank, if you run them to 50%, that’s 180Ah. @12V, that equates to around 2000 watts for 1 hour and the battery is already at 50%. Jip, sounds stupid doesn't it.

It would be a lot more feasible to expand your hot water storage capacity and maybe control then remotely through a sufficiently capable¬†smart switch, and if you know you have guests coming, you can turn it on remotely and ensure there‚Äôs hot water in advance.¬† Have got enough capacity in the geysers, the problem is that the booster pump starts up as soon as flow goes through it.¬† i have already increased the shower heads to double the flow-rate.¬† I think some guys do things in the shower, which is meant to be done in a room,though.ūüėČ

Last observation. That multi plug normally has a 16A plug on it but depending on the quality, may not be able to sustain loads at 16A.  Bought from Mica as a normal plug extension for household.  Could you please elaborate as to your concern.

Thank you kindly for your assistance/help Vassen.
 

 

Edited by phalaborwa
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2 hours ago, RyanG said:

You are reducing the two new 100amp/hr to 80amp/hr in series,  and in this config you cannot keep them separate as @Vassen said. I played around with this kind of home made for some years, this year we only went into solar properly because of eskom. We have debated at length the geyers. I have the Geyserwise system (12K at the time), most people use the solar inverter. So far best solution is gas, do you have good gas supplies in your town look into using a gas setup for geyser. The geyser is just a much bigger kettle really? A gas setup is by far also the most cost effective.

RyanG,

"..You are reducing the two new 100amp/hr to 80amp/hr in series.."  No RyanG, I placed them in Parallel.

I believe you are correct that I should go the gas-heater way(replace the geysers) but I have a problem with that at my thatch-roof chalets.

Thanx for your input/help RyanG.

Edited by phalaborwa
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2 hours ago, GreenFields said:

I think you should strongly consider a water pressure tank in your plumbing setup. Roughly for the cost of one 100Ah battery you could get a 100l tank that keeps pressurized water on standby for multiple toilet flushes and short showers. Re-filling the pressure tank with the booster pump should take less time than you spend filling toilets through a valve, and should help to extend the life of your batteries and pump.

"...I think you should strongly consider a water pressure tank in your plumbing setup..."  GreenFields, this/that is one of the main reasons I started the solar..., to be able to pressurize the water system with the booster pump. Am I missing your point here?

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1 hour ago, EdDee said:

Hi @phalaborwa

The system you have put together there is fine for lighter loads and a few very short term surge loads - At 12v, the losses add up quickly! Quite true EdDee

But all is not lost - Try and get away from pumping water until it is an emergency -Women do not really understand us spending all that money on solar and then telling them they can not pump water to do the washing or telling the guys renting, they can't flush the toilet.ūüėĀ(But you are right, we do not water the garden during black-outs). The inverter would be better spent running lighting and small loads, such as tv/sound system etc - the creature comforts that make "no power" bearable.

Instead of pumping water on demand, could you possibly install a header tank (unaware of your roof height and space)¬† - A small 200 or 500L tank, with a float valve to top it up when water pressure is available, which then gravity feeds your cisterns and showers - If you can get it to about 10m, that equates to around 1 bar of pressure, which will run the lower pressure gas geysers and be more than adequate to fill the toilet cisterns.... 10m sounds a challenge to get a tank to, but there are some easy tricks to doing it, even higher, even alone that barely break a sweat to get it done.... (Takes more effort to dig the holes for the base posts.)(I am 66years old)ūüėõ Also, if the cisterns are taking a very long time to fill, possibly ream the openings of the float valve a little larger(Or is your piping caked with lime perhaps) - I did this when I installed my grey water flushing system - The orifii were opened from about 2mm to around 5mm dia,(My very next project is to do exactly that) as the grey header tank sits at barely 4m altitude - Cistern filling takes little over a minute....

As to running different Ah rated batteries in parallel, I do NOT agree with the previous posters, on the proviso that the chemistry/style of batteries are similar - ie do not mix flooded batteries with AGM etc - if your deep cycles are all flooded cell lead acid, of similar chemistry, they are compatible, the charge/discharge curves are close enough to be similar, and they should cohabit quite cheerfully(they are compatible EdDee)  - One thing that I would recommend, would be the addition of a good old 15A(even an AC one) circuit breaker on the positive pole of each battery before it goes into the main positive buss line - Should a battery short a cell by dropping a plate or for some other reason, the reverse current supplied by the other batteries could amount to enough to cause quite a bit of damage, to say the least. In a perfect world, each battery should have leads the same total length to the buss cable, so allowing each battery to be at as similar a voltage as possible during its charge/discharge process. With dissimilar rated batteries, small over/underages will occur but if you maintain the similar lengths as short as is conveniently possible and the buss cable/bar as large a sectional area as is possible, these over/unders should be relatively negligible.... I have attached a few pictures for your comment

I no longer have a header tank that I use for potable water, but what I have done, to minimize pump on/off cycling, is to add some really basic air accumulators on the pump output line(referred to above as pressure tanks) - they are simple, work well, and are virtually indestructible. Simply put, take any airtight, corrosion resistant cylinder(Old Stainless Beer keg, Old Ali CO2 extinguisher), invert it, screw in an adequately sized T piece, and plumb it into your pressure line on the outlet of the pressure pump. The idea is to trap an air cushion in there that the water pump pressurizes when it is running - Set your pressures on your pump(if you can) to come on as low as possible and to stop pumping at as high a pressure as is possible - The accumulated pressure in the cylinder will amount to around 50% of pressurized volume, sometimes a bit more, of pressurized feed to the house, before the pump has to kick in again... Not only does this save quite a bit of inverter load (getting the pump moving takes a fair whack), but also lengthens the lifespan of the pump quite considerably in my experience. One could even place these homebrew accumulators at various locations that are convenient along the pipe - I have one 20L unit close to my kitchen and one close to the bathroom on the external walls.... The downside of them is that about every 3 months or so, you will need to turn off the water pressure/pumps and open a tap or valve that is at a lower physical height than the accumulator, to drain any excess water and allow atmospheric air to take it's place (you will notice it is required quite easily, the pump starts more often than it should) - The air does tend to dissolve into the water over time and the trapped air volume tends to decrease... but that is a small inconvenience overall...

As to running your 2kw water element on the inverter - I wouldn't, certainly not on a 12v Inverter and definitely not on the one you have in the picture! (without seeing the exact specs for your unit, if made of chinesium,ūüėĀ they are usually rated and labelled at their maximum surge power, not their running average maximum - 4kw surge rated inverters are normally around 2.2 to 2.5kw highest nominal constant load. Even if the inverter is capable of supplying the power, your batteries wont take it for long - to put it in perspective, today, we had some good sun and I shunted about 1.6kw into my "dump load" geyser (gives mildly preheated water to my gas geysers) for around an hour, maybe a bit less.... Water temp in the tank went from 17 to 21.4C .... Its around 250L or so... A better solution for water heating is by using a waste oil fired heat exchanger system, but, like anything, the worse the fuel, the more the maintenance... (I won't get into that here)....

Hope this is of some help...

Cya

E

 

 

 

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54 minutes ago, phalaborwa said:

"...I think you should strongly consider a water pressure tank in your plumbing setup..."  GreenFields, this/that is one of the main reasons I started the solar..., to be able to pressurize the water system with the booster pump. Am I missing your point here?

He is talking about something like this: https://www.builders.co.za/Garden-%26-Pets/Watering-%26-Irrigation/Irrigation-Pumps/60L-Horizontal-Hidrosphere-Pressure-Tank/p/000000000000632386

It's basically a tank with an expanding rubber balloon inside. That way when the pump is off the water still stays pressurized.

So normally you would run the tap at a low flow rate and the pump would be on the entire time. With a pressure tank, you can use the tap for a long time (I think it's about 30% of the tank volume depending on pump pressure rating) before the pressure gets low and the pump has to turn on. When the pump does turn on it only has to refill the tank, and because the flow isn't being restricted it will fill up in very a short time.

I also highly recommend getting a pressure tank. Saves a lot of power and reduces wear on your pump. Also, if you fill it in the evening it doesn't matter if your batteries run low because you won't need to run the pump (which can cause a voltage drop and cut the power).

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45 minutes ago, tetrasection said:

He is talking about something like this: https://www.builders.co.za/Garden-%26-Pets/Watering-%26-Irrigation/Irrigation-Pumps/60L-Horizontal-Hidrosphere-Pressure-Tank/p/000000000000632386

It's basically a tank with an expanding rubber balloon inside. That way when the pump is off the water still stays pressurized.

So normally you would run the tap at a low flow rate and the pump would be on the entire time. With a pressure tank, you can use the tap for a long time (I think it's about 30% of the tank volume depending on pump pressure rating) before the pressure gets low and the pump has to turn on. When the pump does turn on it only has to refill the tank, and because the flow isn't being restricted it will fill up in very a short time.

I also highly recommend getting a pressure tank. Saves a lot of power and reduces wear on your pump. Also, if you fill it in the evening it doesn't matter if your batteries run low because you won't need to run the pump (which can cause a voltage drop and cut the power).

tetrasection ;

I had the exact system running before I went over to the Flow-pressure system(Iwill check on my external hard-drive, if I still have a picture of it) but yes I see the point you guys are making.

Thanx a lot for all your input guys.

Edited by phalaborwa
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6 hours ago, RyanG said:

RyanG

I read through all of the comments on that webpage and found that there are differing opinions from most of them, but thank for once again bringing this very important topic to light.

I have done that and hope the batteries do not destroy themselves.

Edited by phalaborwa
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5 hours ago, Nexuss said:

Those wires look way to thin for a 60 Amp breaker.  And that battery picture looks like a fire hazard . You should be using fine stranded muuuch thicker cable made for DC current.

What amp rating isolators do you suggest I use Nexuss, as I plan to make the/my system more safe by buying the correct ones.  Those were in my store for 40years and came in handy, rather  than using none.

Please point me to a website which is simple to understand.

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How to Charge Lead Acid Marine and RV Batteries in Parallel

https://www.impactbattery.com/blog/post/how-to-charge-marine-and-rv-batteries-in-parallel

Can 2 Batteries with Different Amp Hour Ratings be Wired in Parallel

https://www.etrailer.com/question-130191.html

Electrical Myths, Part 3: Mixing Batteries of Different Ages/Capacities

https://rvnerds.com/2017/08/07/electrical-myths-part-3-mixing-batteries-different-agescapacities/

Q&A: Mixing Battery Sizes In One Bank

https://www.morganscloud.com/2011/10/03/mixing-battery-sizes/

Interesting reading ūüėČ

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42 minutes ago, phalaborwa said:

https://www.etrailer.com/question-130191.html

My thoughts when I read this. I have a torch. I used it until there was only a faint light, It has four batteries in parallel, I open and only change two. Torch is working great after only changing two of the four. The other two are old and not the same voltage/ amp anymore. Should not be a problem?  Lots of conflicting information. Did you pay R4000.00 for two 200w or was there other things? Do you have a china mall. I made a small battery solar charger  a few years back with a 100w panal and a PVM charge controller to charge a 7AH(gate , security etc battery). I think the whole lot set me back under R800.00.  Something like this.

https://www.takealot.com/all?_sb=1&_r=1&_si=059e7f3422a6404cd83dffe1afcb9847&qsearch=Solar Charge Controller

 

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1 hour ago, RyanG said:

"...Lots of conflicting information..."¬† I quite agree RyanG ūü§™

"...Did you pay R4000.00 for two 200w or was there other things? Do you have a china mall..."  Bought 2x 150watt panels about 6months ago for R1500 each and nearly fell on my back this morning when I saw the price on the box the panel was in(R2620.00), then bargained the price down to R2000.00 per panel(told him I will purchase two).

"...I made a small battery solar charger  a few years back with a 100w panel and a PVM charge controller to charge a 7AH(gate , security etc battery). I think the whole lot set me back under R800.00.  Something like this..."

https://www.takealot.com/all?_sb=1&_r=1&_si=059e7f3422a6404cd83dffe1afcb9847&qsearch=Solar Charge Controller

I attached a picture of my old pwm controller which I will use with the two 150watt panels to charge the battery in conjunction with the new panels and the blue JN-MPPT-MINI 30Amp controller.  In other words, I will be using a pwm and an mppt controller with 4 panels to charge one battery bank.(two panels on the mppt and 2 panels on the pwm contoller).

 

 

IMG-20210621-00132.jpg

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