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Re: DC Geyser Element

Posted: Fri May 27, 2016 4:57 pm
by ChrisF
CLEAN YOUR PV PANELS !!!!!!!

:thumbup: :thumbup:
the last three months have been a bit of a blur .... so I knew I had to clean the pv panels, but just never got to it ... :shh:

Last Saturday I finally did.

EDIT : not that easy to confirm the exact power saved per day - with winter weather causing daily fluctuations in what can be harvested .... :crazy:

CAN confirm that the afternoon water temperatures IS now a few degrees higher after cleaning the panels ! :thumbup:

and visually it looked like no more than a thin layer of dust on the panels !!

Re: DC Geyser Element

Posted: Fri May 27, 2016 5:14 pm
by Mud Dog
I have often wondered about this and thought that if there was a difference to be gained, that it would be small and insignificant. Thanks for the 'heads-up'. :winkx:

Re: DC Geyser Element

Posted: Fri May 27, 2016 8:43 pm
by ChrisF
Andy I spoke to my neighbour. We will test his system, and then clean it and test again ... try to see if he has a similar increase in efficiency.

Even my wife has noticed the Geyserwise now shows a higher afternoon water temp than last week.


Obviously one would need two exact systems with exact water usage to be able to absolutely quantify the gains of regular cleaning.

My results are hardly scientific, weather differences, usage differences, just too many variables that could explain what we are seeing. But just too much of an improvement to ignore !


Should add that my panels are only at about 10 degrees. At a greater angle it would be visible above the rim of the parapet wall .... My neighbours are at an optimal roof angle of near 30 degrees. the angle obviously impacts on the amount of energy it can harvest.

More so, it impacts on how rain can wash the panels .... My pool panels are at 3 degrees, with the geyser panels at 10 degrees. You can SEE the difference in dust gathered on the panels !!


I am adding a tap ontop of the roof. Short hose and and broom with water sprayer, it takes 2 minutes to clean the panels. Really not an issue or shlep.

Re: DC Geyser Element

Posted: Sat May 28, 2016 9:50 am
by Mud Dog
I can see mine quite easily from the ground and from down there they look pretty clean and shiny. I think the angle (also about 30°) together with the occasional rain or really heavy dew helps keep them clean. I'll go up there one of these days in any event and check it out. A washing / sprayer system can be a simple and easy thing to rig up if dirt is a problem.

One thing that I have wondered about is that those panels get pretty hot during the day and does this any way impact on the efficiency of the panel. :think:

Re: DC Geyser Element

Posted: Sat May 28, 2016 3:00 pm
by ChrisF
yes, there is a discrepancy between the lab ratings and the lower actual output at real world temperatures ....


rigged up the tap on the roof today. Now it is a two minute job to clean the panels.

Re: DC Geyser Element

Posted: Sun May 29, 2016 10:33 pm
by dax021
Excuse the hijack, but seemed the best place to pose my question. A friend of mine had a DC element retrofitted to his geyser (I think 200L). Has a Geyserwise and 4 panels, which look to be about 100W each. The system has never worked as well as promised even on sweltering summer days. His panels are split with 2 facing east and 2 facing west. Is this a wise way to mount panels? I might be completely wrong, but it is my understanding that if 2 panels are in the shade and 2 panels in full sunlight, then the system will only produce at the rate supplied by the 2 shady panels, i.e., the shady ones pull the sunny ones down to their output. Is this fact or fiction?

Re: DC Geyser Element

Posted: Mon May 30, 2016 6:47 am
by ChrisF
Peter it depends on the connection, ie series or parallel.

Have a friend with a large system where the bulk of his system is on the west side, and only a small section could be fitted facing north - it is connected in Parallel, thus each delivers as much as it can dependend on the sun on it.

In series this will NOT work good !! The volts will remain too low ....


Do you know when it was fitted ? Over the last few years Geyserwise has developed FAST. Went from 750W max to 1100W, and so their panel selections also changed drastically.


Right now you can use 3 off 300W 36V panels in SERIES - this gives the maximum system volts, but not the max power. The other option is to have 6 off 170W 110V panels in PARALLEL. This produce the optimum power and volts for the element, BUT it take double the roof space.

My neighbour has the 3x300W and I have the latter. My overall efficiency is better than his, by more than the 120W difference - we do believe the better voltage is part of this.



My GUESS - your friend has a series set, that never gets to the correct volts ....

Re: DC Geyser Element

Posted: Mon May 30, 2016 9:33 pm
by dax021
Thanks Chris, I'm going to Calitzdorp (where the system is installed) in a couple of weeks. I'll have a better look at how it is connected, I now at least know what to look for. System was installed about six months ago. Thanks again

Re: DC Geyser Element

Posted: Tue May 31, 2016 6:41 am
by ChrisF
Six months back it should be the current 1kW DC 2,5kW AC element - same that I got in October last year.


Also check if he got the DC-to-DC unit with it.

During the initial install we got the polarity mixed and popped a fuse in my DC-to-DC unit. Ran the system for 10 days without the DC-to-DC while it was repaired. MUCH better efficiency with the DC-to-DC unit.


PS - at work we have installed some 200 solar hot water systems for one client ... you will cry when you see the mess some installers make !! Even had one panel on a south facing roof !

Re: DC Geyser Element

Posted: Tue May 31, 2016 9:07 pm
by dax021
Thanks again Chris. Will check when I'm up there. In the meantime I've asked my mate to send me any info he got with the system.

Re: DC Geyser Element

Posted: Wed Jun 01, 2016 6:17 am
by ChrisF
dax021 wrote:Thanks again Chris. Will check when I'm up there. In the meantime I've asked my mate to send me any info he got with the system.
some photos would be handy .. :thumbup:

Re: DC Geyser Element

Posted: Wed Jun 01, 2016 6:40 pm
by ChrisF
SO lyk ons garage dak ....

5x 100W 44V panele vir die swembad pomp
1x 100W 21V paneel vir die 100Ah battery vir die ligte stelsel, + radio vir die braai kamer en garage, + inverter as dit sou nodig raak ...
swart-pype om die swembad water te verhit, vloei word verskaf deur die pv pomp.
6 x 170W 112V panele vir die geyser.


ek het die plate plat gehou - hou nie van plate wat op rakke staan nie .... maar dit beteken dat die plate gereeld skoon gemaak moet word. Ook heelwat swakker in die winter as dit so plat lê. Help as jou huis n 35 grade dak het wat Noord kyk ...

Re: DC Geyser Element

Posted: Wed Jun 01, 2016 7:08 pm
by ChrisF
uit n regulasie oogpunt -

onthou dat wanneer jy die huis wil verkoop gaan jy n elektriese COC benodig.

in die Wes Kaap moet jy aansoek doen vir toestemming vir enige PV stelsel wat jy wil INTEGREER met jou DB. Dit is die eerste stap in n klomp regulatoriese gemors.

My stelsels is NIE ge-integreer met my huis bedrading nie. Dus buite al die vereistes van die Wes Kaap.


In die Wes Kaap hoef jy nie aansoek te doen vir LOS-STAANDE stelsels nie, die wat nie ge-integreer is nie.



Dan is daar steeds die storie van n COC vir huis bedrading, wat dan ook die pv installasies insluit. Die moet steeds deur n elektrisien gedoen word, en afgeteken word. Die huidige COC form maak nog nie voorsiening vir PV installasies nie. My buurman het bevestig met die plaaslike owerhede dat hy n deel van die COC form dupliseer en aanheg, spesifiek om die pv installasie af te teken. Goed waarna hulle kyk:
- earthing van die panele (check - myne is reg)
- DOUBLE pole isolators, beide die positiewe en negatiewe dradr moet ge-isoleer word. (2 van my drie stelsels het dit, die ligte stelsel gebruik ek n fuse om die positief te sny .. sal nou n double pole isolator hier insit)
- draad diktes, versus fuse ratings ... (WEET myne is reg ! my drade heeltemaal ge-oversize)
- LABELS - vir die COC moet die isolators en fuses duidelik gemerk wees (sal nog n paar labels aanbring op my stelsels)


Daar is n nuwe COC form oppad wat voorsiening sal maak vir die pv installasies ... ten minste is daar darem nou n manier om dit wettig te kry. Sal dit so gou moontlik in plek kry, en deur gee vir my versekering. Soos met n gas-stoof installasie is dit beter om die papiere deur te gee vir jou versekeraar. Solank hulle voor n eis weet, dan kan hulle dit nie later gebruik as n verskoning nie.

Re: DC Geyser Element

Posted: Sat Jul 23, 2016 5:21 pm
by ChrisF
The seasons have turned .. the sun angle is improving. :yahoo:

Around 21 June we used an average of 4kW.h per day of Eskom power for the geyser - that was on sunny days.


Just one month later this figure has dropped 2,5kW.h on sunny days.

With the heavy rains we have had, and typical Cape Town long dark winter days the eskom usage regularly exceeds 5kW.h per day.



Still on track to save about 75% of our geyser electrical bill for the year :thumbup:

Re: DC Geyser Element

Posted: Sat Jul 23, 2016 5:29 pm
by ChrisF
I did promise to test the before and after of a geyser blanket ....

seems I will be breaking that promise.


In winter my wife takes a bath in the early evening ... after the timer has switched off for the night. Thus we go into the night with a geyser with luke warm water, that is heated at 4:00 for my morning shower. She also does the dishes, further depleting the hot water supply. In theory this is brilliant - as we thus have minimum hot water in the geyser during the night, and thus minimum losses.

Practically it means it is impossible to do a proper test of the geyser blanket .....


There was ONE night that absolutely no water was used after the timer switched off until the next morning. The re-heat energy was only 0,57 kW.h. Since the re-heating is only needed in winter it means that it would take about three years to pay back the geyser blanket - well much longer since our heat losses is typically LESS than this figure as our geyser water is already cooled down after her bath ....


It thus makes no sense for me to proceed down this route.

Re: DC Geyser Element

Posted: Sat Jul 23, 2016 9:15 pm
by Mud Dog
I tend to disagree with your reasoning there Chris. You're omitting the extra insulative effect that it has throughout the day, not just at night. This will be a bit more significant on colder days and especially in the winter months. Every little bit of heat that is retained is that much less that has to be reheated.

You also don't need to buy a pricey commercial geyser blanket - just make one up yourself by wrapping your geyser with *Isotherm which is quite inexpensive and you should be able to get a few off-cut lengths mahala through your dealings with the construction industry. :D:

Re: DC Geyser Element

Posted: Sun Jul 24, 2016 7:36 am
by ChrisF
uhm jaa ... okay, net nie lus om nou in die dak rond te kruip nie ... :crazy: :shh:

YES, there are more savings to be had. But with my current setup I get enough solar power that my "rand savings" will be minimal.


Might still go this route, but it will not be possible with my current setup to properly measure the "day round" savings due to a geyser blanket.


Fact is that a real life test as I am doing now shows up the major differences to a "lab-test". But this is a whole different topic ... :subscribed: