59 minutes ago, plonkster said:

So you pay more for the extra flexibility. That's my argument for the blue stuff... :-) How much more would you be willing to pay...

Yeah but looking at the math's at what the blue is asking just doesn't make sense. (even at cost price)
If you go and buy the Infini V series. The one @Jaco de Jongh got for 17k I think he said (the new grid tied one)
5kva with a 3000w SCC, anti islanding all included. and add on this the BMV. That's 20k
The blue is good man but for 20k I cant get anywhere close to that

PS
Just for the record I have installed and configured a decent blue system (40kva with matching SCC's etc) and monitoring it till this day.
Still just too overpriced for me for what you get

There is always the middle of the road approach too, which is to have a little bit of both.

In some ways, that's how it turned out for me. Due to a lack of roof space, my solar geyser is a little too small and except for the hottest month, we use a little bit of electricity every day. It would make perfect sense to heat that little bit of extra (seeing as I have a prefeed system too) with surplus PV. I already know I'm going to use at least a hundred liters of hot water every day. I might as well heat at least a hundred liters using the most cost-efficient method I know, namely a solar geyser, and use the inefficient flexible PV side for the rest.

So this is something to consider: Install a "Heat box". It's 10k. Designed for prefeed systems. Heat the rest with your surplus PV. You know you're going to use at least X amount of hot water... heat that X amount directly. There is no point in being flexible about that (except maybe if you can sell to your municipality and you're going away for a few days).

4 minutes ago, viper_za said:

Yeah but looking at the math's at what the blue is asking just doesn't make sense. (even at cost price)

In 2013 things were different. There was no Axpert. I don't recall seeing the Infini anywhere. The blue was only a little more expensive than the other decent stuff around. It was the only one you could parallel. Then I discovered that overnight my inverter could do more because new firmware came out yesterday. In 2013 terms, compared to what was available then, the 50% extra I paid on the inverter was absolutely worth the extra functionality.

At today's prices? Probably wouldn't have done that. I would have been here with the rest of you guys bragging about my China-special :-)

Interesting views being shared on this thread.

 

My reasons for choosing the PV system were;

Works with any existing geyser

Will not boil EVER, regardingless of any component failure

Can be turned off when on holiday

25 year warranty on panels

No possibilty of water leaking as a result of heating component failure

No plumbing required

Unaffected by ambient temp, works on cloudy days (Solar Frontier panels)

Can be expanded into PV inverter system

All in all cost is not bad. PV system can be had from R10k excl install. That buys you a 20 tube EV right? Which also works with a 200L geyser

 

Comparing a system that is greater that 50% efficent (ev) with a system that is 10% efficient (pv) makes no sense. Heat pump PV is somewhere in the middle, but still. I am off grid, with no electric backup and produce large amounts of hot water from solar thermal, without such infernal devices as water saving shower heads!

6 hours ago, The Terrible Triplett said:

Thank you.

As a matter of fact, if you have more than 200l or 4 people in the household, heat pumps are far cheaper and better than EV /FP. That advice was researched by more clever people than I, with the numbers to prove it, and you have same factual experience.

 

 

They're only efficient if the ambient temperature outside is warm enough. On a cold day, you would still use the same amount of energy as a normal geyser to heat up the same amount of water to the same temperature level. Most people don't know this, and most sales reps don't mention this. So, in sunny South Africa, for about 9 moths these devices save you some cash, and then it costs the same as any other geyser. 

10 minutes ago, SilverNodashi said:

Most people don't know this, and most sales reps don't mention this.

Well blow me down.

 

Winter in the Cape is a challenge. Question: On a cloudy day, which device will generate the most energy for heating the geyser? PV or EV tubes?

From what I have seen, and it is very unscientific, my EV tubes are far ahead on that score when I see what the panels produce versus the geysers temp climbing quite a bit on the same day.

40 minutes ago, SilverNodashi said:

only efficient if the ambient temperature outside is warm enough

Well yes, efficiency does vary with the ambient temperature. Here in the Cape, where the temperature never drops below zero, the COP of a good heat pump is between 2.5 and 4. So even on a cold day it's twice as efficient as a traditional geyser. As the temperature goes down, it does get to a point where many heat pumps will turn on their internal element (if so equipped). When that happens, they are arguably LESS efficient than the geyser, because of pumping losses. Unless you live in Harrismith or Sutherland, you can get past this by simply not running the heat pump before 10AM :-)

28 minutes ago, The Terrible Triplett said:

Winter in the Cape is a challenge. Question: On a cloudy day, which device will generate the most energy for heating the geyser? PV or EV tubes?

From what I can see, the thin-film modules sits around 14% efficiency. The "normal" crystalline panels are around 17% or so, but they drop out much faster under cloud. So on average I still think the EV-tube is going to win, even on a cloudy day (because the EV-tube can work with UV, or so I'm told).

This thread's taking some interesting turns

 

Just now, TinkerBoy said:

No. I do not agree with you. I have the heat pump 4 years now. It uses the same amount of power come rain or shine winter or summer and it always takes the same amount of time.

Check the spec sheet for the heat pump. They usually have a chart or something on there showing how it degrades.

On heat pumps, what are the service intervals and costs per service?

18 minutes ago, TinkerBoy said:

...  because of its 1.4 kw load ...

I know it takes 2 hours to heat up the tanks from below 30 to 54 degrees, no matter what time of year, I timed it and plotted the data.

But this statement I would question, on pure gut even if you have the data.

I don't have a heat pump and I am not going to Google to try and prove anything. 

Question in the sense that does the heat pump on a hot day use the exact same power as on a cold day? What am I missing?

NOTE: I clarified the post.

1 hour ago, plonkster said:

From what I can see, the thin-film modules sits around 14% efficiency. The "normal" crystalline panels are around 17% or so, but they drop out much faster under cloud. So on average I still think the EV-tube is going to win, even on a cloudy day (because the EV-tube can work with UV, or so I'm told).

SineTech has Thin Film, Poly and Mono crystal panels on their roof, and they've been logging stats of each system. On the other end, they use the same inverters and battery bank. To date, the thin film panels produce, on average, 11% more energy than the poly and mono panels.

39 minutes ago, TinkerBoy said:

Plonky I don't care what the specs say. I am talking about using the thing on a daily basis. I know it takes 2 hours to heat up the tanks from below 30 to 54 degrees, no matter what time of year, I timed it and plotted the data. I used that info to size my bank when I was still using the Axperts because of its 1.4 kw load. And less time if the tanks are on temperature and people use hot water. I am not a vendor or installer trying to convince anybody. I am talking about my experience and what I have seen in the data. Hard data not a spec sheet. But OK I said my bit. Use is, don't use it. Betaal self die skool geld.

Your mileage will vary from the next person's. A lot depends on where the tank was installed. I've seen many tanks underperform (i.e. using more energy than what the client thought) cause it was installed in a cool section of the house. Different brands also have different mileage. I'm not a sales person of these things either and don't install them (not a plumber) but purely report what I have seen in the field. 

@SilverNodashi are you talking about the all in one units?

Just now, viper_za said:

@SilverNodashi are you talking about the all in one units?

now that you mention it, yes

5 minutes ago, SilverNodashi said:

now that you mention it, yes

Saw complaints on these and even had one at a resort once it just looked like it ran all the time, but the retrofit ones using the existing tank in the roof seem to fair much better from the research I did a while ago

1 hour ago, TinkerBoy said:

Do you have a heat pump ?

No. Not yet anyway. But I was researching this Tasol heat pump last month (a rebranded Deron, from China, looks  sort of good). That particular heat pump has a COP of 3.2 at an ambient of 20 Centigrade, but goes down to about 2.5 at 7 Centigrade. Now that's narrow enough that you might not notice unless you monitor it very carefully.

I'm sure the ITS does better. Point is, it's right there in the spec sheet usually. It does get harder to exchange heat in an environment where it's cold, and conversely, it gets easier if there is abundant heat to absorb.

Also, I was looking at this American heat pump (someone was swindling one on a local Facebook group real cheaply) that had a COP of only 2.5 in GOOD conditions, and went right down to 1 (which is essentially a straight heating element) before you even hit zero. So there really are pretty crappy heat pumps out there, but our climate here in SA (even in the colder parts) is pretty mild, so I'm not really surprised that you're not seeing a big variation.

Thin film is a bit of a tricky one you get greater variance in output from one manufacturer to the other. What i mean to say is you get really good thin film and realy crappy depending on the amount of layers or something. I stand to be corrected here but thats what i understand. The more layers the more expensive.

Sent from my SM-G900F using Tapatalk

On 6/21/2015 at 6:09 PM, Chris Hobson said:

 

 

Just now, ebrsa said:

 

It's quite annoying,isn't it? You want to quote something and the text just disappear. Or you want to multi-quote and can't cause the forum software doesn't allow it. 

Right, I quote ITS, the supplier of Tinker's heat pump, feedback.

"Efficiency is relative to application and capital invested. Hence depending on the application you might find that the one technology is better than the other, but in another application it can be the inverse. It is therefore key to rather invest in the right technology for the application to ensure your ROI is optimal."

I have said to the people living in our house, the fact that we can afford it, does not mean we have to use as much as we want. Saving water is the number one priority, therefor we also save even more on water heating costs.

As I have also said before, I wished I had gone double with EV tubes, but, I did not so I had to make a plan. System was paid in 22 months.

"A solar EV system can provide a bigger saving than a heat pump but for that the solar system needs to be oversized and water usage patterns needs to be adjusted. Typically you need double the volume of hot water that what you would need for a normal electrical geyser or a heat pump system."

Here is the document. Supports Tinkers own experiences as well as mine. We both are right. 

So it goes right back to what do you need, want? Find the best solution for YOUR situation.

ITS - Should I buy solar or heat pump.pdf

32 minutes ago, ebrsa said:

We have to consider that everyone who posted here have different needs. So it is not surprising that there is such a variety of opinions. My own 16  EV tube heater with a homebrew Arduino controller was about R7500. In winter I need to switch Eskom power feed on at times. Consumption according to the geyser's Owl meter was 37Kwh for August. During summer no Eskom power is used. At R2.0406 per Kwh for over 600Kwh I calculate that I save about 3000 Kwh or R6000 per year.That amounts to 80% return on capital. Only Ponzi scheme promoters and fraudsters offer such returns but mine fortunately is real. So I would suggest calculating your return on capital for a system that suits your needs with due consideration for savings when using a heat pump or resistive requirements.That seems to me to be the only logical approach. If the latter is not much as in my case, I cannot justify a heat pump. Clearly Tinkerboy, for example, has made his case considering his hot water requirements.

 

On 2015/08/15 at 7:46 PM, EcoElement said:

 

• Studies have shown that within the domestic market, 40-60% of your power bill is in heating from geysers. As an Energy Efficiency Advisor, I can confirm that the titanium element is far superior to the conventional element in your geyser. The 150 litre geyser is probably the most common on the market...about 80% and the 200 litre accounts for about 20%. The 150 litre geyser, when on, generates 3000 watts per hour. The 200 litre generates 4000 watts. The main difference between a conventional element and a titanium element is the technology with which it is made. Heating elements made with PTC (Positive Temperature Co-efficient) chips do not use resistance wire as a source of heat. Instead, it uses a number of ceramic chips that have self-limiting temperature characteristics. What this means is that the water in the geyser is heated up at the same rate as your regular element (3 kwh) would but at 50% less power (1.5 kwh), hence a 50% saving in costs.