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Solar retrofit


Noobie
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So I want to do the exercise to see what it would cost to change my existing 200l Kwikot geyser with a 4kw element to a solar system. Capital outlay as well as maintenance costs 

Currently my geyser is on a time switch which is set to switch on for 90 minutes a day from 14:30 to 16:00 and runs off of council electrical supply.

The geysers thermostat is set to 40 degrees which is hot enough to have a shower without having to turn on the cold water tap.

The geyser is in the roof and is wrapped with a geyser blanket.

I have read a bit about VT vs FP collectors as well as pumped vs thermosyphon systems and still am not sure which way to go.

I got a quote for the following Kwikot kit and was wondering if anyone could chime in on it: http://www.kwikot.co.za/brochures/Kwiksol%20Solar%20Retrofit%20Direct%20System%20(Nov%202015).pdf

I want to use the SOL-200-RT model, quoted R5820 incl VAT from the local plumbing supply wholesaler.

Im concerned about the 12v pumps life span and the maintenance of this system. I'm sure I read that you should flush these collectors out annually.

Ideally I would like to go thermosyphon but I am not prepared to relocate my geyser higher up in the roof and encounter another expense

Also if anyone could recommend a solar geyser installer in Gauteng who knows what they are talking about, I would appreciate it, I want to get a quote to install this kit.

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I have a ITS system. I have a 4kw heatpump (1.2kw power) and 24 tubes on 300l water. 2 tanks of 150l each. The tubes cost me R26k installed and the heatpump was R12k on the Eskom rebate. Had the heatpump for 3 years now. Works very well. Had a lot of problems with the tubes in the beginning as the installer did not know what he was doing. Got a new installer that fixed the system on ITS account. The heatpump only comes on on cloudy days. Not sure why your units are so cheap, seems to good to be true. Is that price installed?

The problem we had with the tubes is our water was off for a weekend while we were away. As we have a water purifying system in the kitchen it used the water in the cold water line as the taks are the highest point of the system. As a result  the tubes on the roof hit 140 degrees as there was no water in the system. It melted all the cladding and fried the motor. This is now fixed. But I still dont trust the system not to overheat if we are not there as nobody is using any hot water, so the temp in the tanks just go up and up. The ITS system does have a holiday fuction that cools down the water at night. But I still dont trust it. So for now I cover the tubes with vinyl sheets so the sun can not heat them up. 

I am working on a auto system that will close and open based on the temp or if we are not there. I am just working on a plan to see if I can do it cheaper. I dont want toy get on the roof all the time. 

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I finished my DIY solar geyser conversion 2 weeks ago. Total cost was just under R12k. Collector is the biggest part of the expense but the smaller parts quickly add up (Geyserwise, pump, copper pipe and fittings). 

Was running on 4kw per day for heating the geyser. After the installation was done it dropped to an average of .5kw for the first 10 days

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12 hours ago, Noobie said:

The geysers thermostat is set to 40 degrees which is hot enough to have a shower without having to turn on the cold water tap.

Watch out for legionnaires disease. :-) Have to take it above 45 centigrade to kill the bacteria. Much better to set it at 50.

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11 minutes ago, jdp said:

The heatpump is set to 54 degrees. That is save to kill all the germs. 

Yeah I'm commenting on Noobie's 40-degrees setup. Apparently it's okay if you only take it up once every few days. I believe the Geyserwise will even do it for you if solar doesn't get it up there regularly enough.

So one thing pops into my mind this morning: Are solar panels cheap enough yet to just stick a bunch of them on the roof with a DC element? Well... maybe. If it takes 1.16Wh to heat one liter of water by 1 centigrade, and if we assume ambient water is at 15 degrees and you want it at 55 (delta = 40), then it takes 150 * 40 * 1.16 ~= 7kwh to heat your average 3-bedroom house's geyser. To generate 7kwh of solar electricity, assuming an average of 5 hours of good sunlight, will need 1600W of solar panels. So lets make that 1800, or 6 x 300W panels. That's 18k, which given that a solar geyser is between 15k and 30k... is actually sort of getting there.

Of course, there is one big problem in my assumption. Cloudy days. On a cloudy day, an evac tube can still absorb UV. A PV panel is next to useless though.

So... get the evac tubes.

I have a flat panel. It's next to useless in winter.

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Oh, and time switches. They are there to help our struggling supplier. They don't actually save you money. Your average geyser has a standing loss of 2-3kwh a day (depending on size). It loses this energy regardless of whether it is on or off, and it needs only 30 minutes to put it back. There is a TINY bit of savings because of Newton's cooling law, which basically says that the rate at which it cools down is proportional to the difference in temperature, so by leaving it off for longer periods you are benefiting a little bit from slower cool down... however, over a 24 hour period you are very much in the linear range of this curve... so you probably save about 50 cents... if you are lucky. Not worth the angry spouse who had to take a cold shower.

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To be honest I think I wasted my money to install the tuabes. The heatpump heats the 300l to 54 degrees in 2 hours. It runs form 1 to 3 pm. Using 1.2 kw of the solar systems power per hour. So then the panels have something to do in that time and because the solar panels work even in cloudy weather and do not need uv to heat up I think it is a better option. 

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I installed tubes about 6 years ago. They where rather expensive back then, using the existing Kwikot geyser, was about R28k. 22months later it was paid for.

BUT, I have to mention, there where rules that SWAMBO and her pups HAD to abide by ... or ELSE ... :D (yes, there where attempts at riots ... teargas and water canons where deployed.)

One little caveat. One year after installation as I was warned will happen, the Kwikot geyser burst. No issue, it was a insurance claim so I asked for the monies and adding a few grand bought a 200l Duratherm geyser. This one is installed outside the house. Have had it with bursting geysers and the resulting mess.

Savings? From about Sept/Oct till about May geyser is using ONLY EV tubes to heat water. In winter only 2 hours per day, 4-6pm on Eskom.

So for me EV tubes have saved me a sh_t load the last 6 years ... with the now friendly support from SWAMBO and her pups. ;)

Only regret I have, should have gone for 400l system.

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15 hours ago, jdp said:

I have a ITS system. I have a 4kw heatpump (1.2kw power) and 24 tubes on 300l water. 2 tanks of 150l each. The tubes cost me R26k installed and the heatpump was R12k on the Eskom rebate. Had the heatpump for 3 years now. Works very well. Had a lot of problems with the tubes in the beginning as the installer did not know what he was doing. Got a new installer that fixed the system on ITS account. The heatpump only comes on on cloudy days. Not sure why your units are so cheap, seems to good to be true. Is that price installed?

The problem we had with the tubes is our water was off for a weekend while we were away. As we have a water purifying system in the kitchen it used the water in the cold water line as the taks are the highest point of the system. As a result  the tubes on the roof hit 140 degrees as there was no water in the system. It melted all the cladding and fried the motor. This is now fixed. But I still dont trust the system not to overheat if we are not there as nobody is using any hot water, so the temp in the tanks just go up and up. The ITS system does have a holiday fuction that cools down the water at night. But I still dont trust it. So for now I cover the tubes with vinyl sheets so the sun can not heat them up. 

I am working on a auto system that will close and open based on the temp or if we are not there. I am just working on a plan to see if I can do it cheaper. I dont want toy get on the roof all the time. 

This price excludes install, never though about overheating. Does it just circulate the water at night when putting the system into vacation mode?

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5 hours ago, Louw said:

I finished my DIY solar geyser conversion 2 weeks ago. Total cost was just under R12k. Collector is the biggest part of the expense but the smaller parts quickly add up (Geyserwise, pump, copper pipe and fittings). 

Was running on 4kw per day for heating the geyser. After the installation was done it dropped to an average of .5kw for the first 10 days

Louw, care to share the specs of your collectors and pumps etc? Nice work, DIY is the way to go

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Really concerning comments about geysers bursting Plonkster

The geyser wise max controller looks pretty good, and I am leaning towards a VT collector with a pump.

Arent these pumps noisy? I ask because the geyser sits right above the main bedroom

I would love a heat pump as a back up for overcast days, but that's just not in the budget

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I installed a 20 tube collector on a 250l geyser. 

I use a Geyserwise Max to control a 12v pump to circulate the water. I decided against a 220v pump due to issue when there is loadshedding (If you lose power for 30minutes in the morning your collector can reach 100C plus, which cause the safety feature to kick in. It means that the pump will not circulate the water till then next day after the collector has cooled during the night when the power domes on agaiin. This is to avoid 100c water being pumped through the pipe). I have a 10w solar panel powering the pump with a 8ah battery as backup.

I am very happy with the performance of the system.

I did not use the retofit kit for a Kwikot geyser. I just made a cut in the warm and cold water pipe before/after the geyser (all after the prsure valvue) and installed a T junction in the pipe that goes to/from the collector.  So the water goes from the warm water side, through a tap/one way valve, to the pump, collector, another one way valve, and then back into the cold side of they geyser (about 6C warmer)

The most difficult thing (excluding movIng my 1.95m/105kg frame through the roof) was drilling holes through the roof tiles. (Start with small drill and then going bigger with no hammer action)

I bought most of my parts online at plumblink, which are about 15% cheaper than buying it at the store.

Use copper pipes as they can handle high temps.

 

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Yes the holiday function pumps the water at night as well. Cooling the water using the tubes as a radiator. The problem I have with that is then we are on battery power. I have all the parts for my shade system. Just need to make it cheaper. 

DIY is great. But you need to know all about the anti air lock valves and siphon loops and all the other stuff that goes with it. If not then you could end up paying more as your system will fail and do a lot of damage. 

As for Kwikot. I personally know two people who used those tanks and it burst. The plummer that installed our second tank said he no longer installs kwikot as they do not last more than 2 years on avg.

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11 minutes ago, jdp said:

DIY is great. But you need to know all about the anti air lock valves and siphon loops and all the other stuff that goes with it. If not then you could end up paying more as your system will fail and do a lot of damage.

My wife agrees with you JDP.

Prolly from experience watching her beloved(?) she will let you know that in her experience DIY is not only more very expensive but also quite time consuming resulting in lots of new tools and parts never to be used again. She is an advocate for getting the right person in, whom has the tools and the experience to do the job in a hour or wot some. :D;)

I just have NO idea who HER BELOVED is anymore ... gmpf! :wub:

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Noobie I agree. That is wat happed to me with the first installer. I knew more than he did. In fact he told my wife that they should phone me and ask me how it should work. As I wanted to know how hot the system is while I am not there I created a Arduino controller sertup that I hooked up to the copper pipes between the tanks and comming from the tubes and heatpump. With this data I then found out that the piping was not done correctley and that the water was not flowing in the correct direction. I found out that if you open a hot water tap cold water would run through the tubes and cold water would be dumped in the hot tank. Long story short is the first installer ran away as he had no idea what was going on. Second installer could answewr my questions and made the system so the water would flow correctly and even if there was no water the pump would not run dry. Thihs only comes with experiance. So DIY is great but experiance can not be bought. 

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My DIY install cost 40k less than an installer would have charged and had I let the  installer install the Rolls-Royce system he had planned it would have cost north of 600k. My entire install costs less than the battery bank earmarked.

I do concede that part of the 40k would have been Blue Energy products since the installer does not trust "those Chinese things". Perhaps I should send him to TTT :lol:  - bird of a feather and all the rest.

Edited by Chris Hobson
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