Apricus Or Hills Evacuated Tube Solar HW System? « Alternative Technology Assn Forums

Alternative Technology Assn Forums » Energy

Apricus Or Hills Evacuated Tube Solar HW System?

(354 posts) (94 voices)

Started 3 years ago by GJOESQ
Latest reply from peter69_56

« Previous 1…91011 12 Next »

swanning_it
Member

micko wrote:
"During poor weather (overcast/raining) when there is likely to be little solar gain then a night time off-peak boost would be the best choice. When the weather is clear and so they is good solar gain then a short boost late afternoon would be the most efficient."

Micko, Steve is in Brisbane. He cannot easily jump from night rate (Tariff 31) to controlled (Tariff 33) or general (Tariff 11). To do so requires a metering change at present and costs to do so. By the sounds of it, Tariff 33 would be the most applicable.

But aside from that, I think I've heard more "facts" about ET in the past few posts than I have in the past few years. Thank you all.

Posted Monday 6 Jun 2011 @ 6:52:50 am from IP #
Sunshine
Member

Micko,
"Systems are sized on Summer output as standard as otherwise you have a huge amount of wasted energy and more expensive system, which still won't give you 100% of winter requirements."
I think this is the reason why alot of solar hot water systems are not performing to expectations because of this policy of sizing a system for summer.
I upsized mine to 30 tube (sales recommended a 22tube system/315l tank) and have made the right decision.
You mention that upsizing causes "otherwise you have a huge amount of wasted energy".
What wasted energy? Solar from the sun is free, we don't pay for it, as yes, my system, other than 4 days of solid rain and heavy cloud last May (technically May is still Autumn), has always provided 100% of winter hot water.

Posted Monday 6 Jun 2011 @ 7:04:19 am from IP #
Sunshine
Member

I disagree with the philosophy of sizing a solar hot water system for summer.
That's like sizing an air conditioner for winter, a heater for summer, a fridge for when you've just had dinner..
Summer hot water use is minimal. It seems anyone who listened to the solar hot water system salesperson, are finding they are having unsatisfactory performance in winter.
It's not the lack of performance of the solar hot water system, it's the wrong choice of product for the application.
I just went with my gut feel that upsizing was a good idea, as who wants to run out of free hot water in winter?

Posted Monday 6 Jun 2011 @ 8:05:04 am from IP #
PeterS
Member

Hopefully things might be looking up, at least a little bit. A different plumber looked at the system today (I think it was the one who actually installed it but I might be wrong). Anyway, we have a small leak in one of the fittings at the tank. He is coming back tomorrow to fix that. I'm not sure how much that will improve temperatures (not much I suspect) but fixing any leak still is a good thing. He suspects a leak in the roof system as well, but it was getting too dark for him to really see. If that is the case though I imagine that may be more significant for temperature - and is also fixable. He will also move the collector to the northern aspect (although that may cost us a carton ). He agrees with Micko that it should give us some improvement, but not huge. He believes that the main reason our system performs poorly (and he thinks it does perform poorly) is that we have a 2 story house, and so the pipe run is longer. He thinks a lot is due to heat loss from the pipes. Not sure there's much we can do about that as they are already insulated. Not sure if extra insulation is possible - or a better grade or something. Somehow I doubt it from what he said. One thing that he did do is change the programming of the controller. He said that with 2 story systems, the controller turns off the pump with still a lot of hot water in the pipe, just due to the volume of water in an long pipe run. He therefore changed the program to enable the pump to run a bit longer and get that water out of the pipe into the tank. I got the feeling that he is hoping that with some of these changes we might get significantly longer between boosting, which would be nice. One thing that I will do is measure the temperature of the return pipe at either end sometime when the pump is running, just to see how much heat is lost that way. Does anyone know more about heat loss in the pipes for 2 stories? Is there any way of insulating the pipes better? I suspect not, because this guy seemed very knowledgeable, and if he didn't suggest it I suspect it doesn't exist, but it never hurts to ask.

Posted Monday 6 Jun 2011 @ 10:19:21 am from IP #
Sunshine
Member

I agree the pipe run length won't help if its long. I measured mine, its around 16 metres x 2, so not optimal either. The insulation appears to be the black hyperlon which I'm sure could be upgraded to better spec.

Posted Monday 6 Jun 2011 @ 11:29:53 am from IP #
Gandini
Member

Sunshine,

You beat me to it in saying it's not wasted energy. Water running down the river is not wasted and time spent drinking coffee and reading the newspaper is not wasted. And solar heated water that is not used because you're away on holiday is not wasted.

Micko makes some good points and it's good to hear from a manufacturer. He's the only one willing to discuss things in a public forum and respond to queries and comments.

However, I disagree with his comment that late afternoon is the best time to boost and the implication that systems sized for autumn/spring or winter are too expensive.

The optimum time for boosting is after the day's solar heating has ended and before you need hot water. One size does not fit all.

If you need hot water in the evening (showers, washing clothes etc) then boost in the late afternoon.

However, if you need hot water in the morning (showers, washing clothes etc) then you can save money by boosting overnight with lower cost off-peak electricity.

We had a 30 tube/315 litre VE tank Edson (formerly AAE) system installed a few months ago. It faces due north and is on a frame oon a flattish roof at about 50 degrees to the horizontal.

The cost was greater than the cost of a 20 tube/270 litre system that could be considered to be "sized for summer". However we were happy to pay the extra cost of the extra tubes, larger tank and - most importantly - the frame to provide better winter performance.

Posted Monday 6 Jun 2011 @ 12:55:04 pm from IP #
cnheu
Member

Hi PeterS, hi guys, it seems my calculations have caused a bit of a stir. I also urge that people don't pass judgement after a quick glance at a few posts on a forum. If you want an honest opinion, why not go to a retailer, that sells multiple systems and let them tell you which one is best. A few troubled cases on a forum (more often than not) don't represent a true demographic of the system's performance.

PeterS, please bear in mind, that those were rushed calculations done after-hours before heading home! After reading what Micko has said, I checked through my calculations and realised that some of the assumptions were wrong.

I think people on the forum may be a little confused since they haven't seen the actual calculations I used. Also, these figures should be taken in with a grain of salt.

______________________________________
PV SYSTEM

I assume you've used this 3kW Suntech system with 190 W photovoltaic panels:
http://www.todaesolar.com.au/solar-power-for-homes/3kW-suntech-solar-power-system-special.php

Area_Panel = 1.58 m x 0.808 m = 1.277 m^2
Area_PVArray_Total = 16 x 1.277 = 20.43 m^2
Energy_Produced = 13.5 kWh (data from PeterS)

So you're getting 13.5 kWh from 20.43 m^2 of solar collecting. I.e. For every m^2 of PV installed, you're generating --> 13.5 kWh / 20.43 m^2 = 0.66 kWh/m^2

PV efficiencies are typically 10-20% efficiency (20% being the highest for mono-crystalline in the market). So if we assume it's well ventilated, cool but sunny day, then it'll be operating at fairly good efficiencies. Say... 15%.

So if it's generating 0.66 kWh/m^2, then it's receiving ~ 0.66/0.15 = 4.4 kWh/m^2 (this is total sunlight available on the north face)

_____________________________________
EVACUATED TUBE SYSTEM. This is where some errors in my judgement were made.

_____________________________________
DATA from PeterS
My temperature readings are:
Time Roof Tank Inlet
07:30 28 33 22
08:50 33 31 29
09:45 39 35 34
10:15 39 36 35
10:40 44 38 37
10:55 44 38 38
11:40 44 41 40
14:15 48 43 42
14:35 47 43 42

Initially, I took the TANK readings (as I was in a rush, but this is inaccurate), really it the INLET temperatures (sensor at BOTTOM), that need to be considered, because as we've discussed, the inlet is where the cold water enters, and the INLET will always be lower than the TANK (sensor at the TOP), so it is a conservative measure. Also as Micko pointed out, it is actually 340 L of water, in our "315L" tank.

Energy_Produced (kJ) = mcdT = mass x specific heat of water x difference in temperature
= 340 [L] x 1 [kg/L] x 4.19 [kJ/kgoC] x 20 [oC] = 28,492 kJ.

So say.. 28000 kJ to be CONSERVATIVE.

Now, converting kJ to kWh (for comparison)

1 kJ = 1000 J = 1000 W.s = 1000 [W.s] x 1/1000 [kW/W] x 1/3600 [hr/s] = 1/3600 [kWh]

Energy_Produced [kWh]= 28000 kJ x 1/3600 [kWh/kJ] = 7.778 kWh.

Area_EvacTubes = 2.82 m^2 (previously I took the area of the frames, not the actual collector area)

So for evac tubes your getting: 7.778/2.82 = 2.758 [kWh/m^2]

Given the same conditions with efficiency of ~ 70%, the eastern face should be receiving about 2.758/0.7 = 3.94 kWh/m^2.

______________________________________
COMPARE EAST vs NORTH INSOLATION

3.94/4.4 = 0.896% or a 10-11% difference between East and North insolation. I.e. More in-line with Micko's values.

______________________________________
CONCLUSION

To my understanding, there isn't a significant difference between East and North. Your system is still performing optimally, but yes an Eastern face has resulted in minor losses. I am guessing other losses may have arisen out of your leak and the long pipe runs.

Without the intention of offending anyone, even with these calculations... any hydraulic or heating systems has FAR more variables to be considered. Many of which could not be quantified without heavy analysis and computational requirements.

Posted Monday 6 Jun 2011 @ 1:21:59 pm from IP #
micko
Member

You guys are really on the ball. I need to be careful what I say!

Yes I suppose the energy is not "wasted". It is being absorbed but then dissipated without being able to contribute to your savings.

From a perspective of cost per kWh and also rebates the systems are sized for summer output. If for example we sized to have 60tubes on a 315L tank, the additional energy generated in the summer would NOT be calculated in RECS calculations and so would not get many more RECS points than a 30 or 40tube system. The cost of the system per kWh is then higher as the rebates contribute quite a lot to the final system cost.

If you wanted to choose a larger system than your household may need... so a 30tube 315L rather than 22tube 250L then that would provide a much higher % of winter contribution, but initial investment would also be higher. A choice for the home owner, but not recommended by manufacturers.

Long line will certainly increase heat loss especially if the pump is cycling on and off. The installer did the right thing by adjusting the controller settings to achieve longer circulation run times... that will prevent heated water sitting and cooling in the return line. So yes the controller can be tweaked slightly to suit the system.

Regarding boosting times - yes I agree that IF you shower in the morning then evening boost is fine. If you shower at night, late afternoon would be best. Maybe I am out of touch with the norm, but I thought most people would shower in the evening after a day of activity.. hence recommending late arvo boost. So it all comes back to what your household habits are... and choosing a boosting method that your suits your needs. As was pointed out you can't really easily switch back and forth from off peak to peak, so it is something that should have been correctly chosen during installation based on communication of showering habits with the installer.

I greatly appreciate all your input into this forum as it is a good opportunity for me to get a stronger understanding of how you are using your system in the "real" world and ensure that our product, documentation, training etc is tailored to match that.

Posted Monday 6 Jun 2011 @ 1:28:25 pm from IP #
PeterS
Member

cnheu, thanks for you updated calculations, it makes more sense now :-). As I said, the plumber has noticed some leaks in the system (including the manifold) that he is going to repair. That should see some improvement (a leak is always a bad thing :-)). The controller has been adjusted, and we will see how that affects things. I am also tempted to try and wrap a bit more insulation around the pipes, at least in the roof space. The pipe run up the house is contained neatly in a channel, and extra insulation wouldn't fit there. When the system was first installed in summer, they put in the tank, but had to come back 3 days later to install the collector, so they had us use the boost to get hot water in the meantime. We ran out of hot water at the end of the 3 days, so in summer it took us 3 days to use the whole tank. I am guessing that in winter we would use the tank up in 1.5 - 2 days if there was no heat input. The plumber seems to think that he should be able to get the system to the point that it could just about replace the hot water we use in a day, but wouldn't be able to heat the tank completely from cold to 60 degrees (which it probably would do in summer). Hope he's right!

Posted Monday 6 Jun 2011 @ 9:27:47 pm from IP #
PeterS
Member

I thought about it a bit more, and this is what I currently think re the calculations. SOme of the tank obviously heated 20 degrees. This is the point at which cold water enters the system, and so at the start of the day, after morning showers etc, there is going to be some cold tap water there, but we don't know how much. That got heated by 20 degress, so the calculation that assumed 10 degrees heating for the whole 315 L tank is probably unrealistically low, but we don't know how much. The new claculations that assume 20 degrees heating for the entire tank are obviously unrealistically high, because we have evidence that part of the tank only got 10 degrees warmer. The "top" sensor is only 1/3 of the way up the tank, so we have no information at all on what was happening in the upper 2/3 of the tank. The day before had heated the tank to 44 - 45 degrees, so somewhere in the top of the tank was probably a volume of water that was already at approx 44 and didn't get extra heating at all, but again we don't know what that volume was. I guess then it seems to me that we actually don't have enough information from the sensors currently fitted to the system for these energy calculations to give any meaningful idea of system performance. I'm more inclined towards being a facts and figures type of person, so that's a bit annoying, but I don't see any way out of it. Need more information!

Thanks

Posted Monday 6 Jun 2011 @ 11:02:14 pm from IP #
Gandini
Member

CNHeu,

I am doubtful about your conclusion that east facing ETs are (only) about 10% less efficient than north facing ETs.

Simple geometry and logic indicates they would pick up more insolation than north facing ETs in the early part of the morning but after noon they would only receive reflected sunlight, not direct sunlight.

Re my previous comments that winter performance could be maximised by tilting the ETs at about latitude plus 20 degrees, the tilt angle would need to be latitude plus 23.5 degrees to orient the ETs perpendiclar to the midday sun and at a slightly greater angle to increase heat input before and after noon.

However, winter insolation is much less than in summer due to the shorter daylight hours and, significantly, the lower intensity of sunlight. The latter factor is why we get sunburnt in summer in a few hours (or less) but not in winter even if outside all day.

The law of diminishing returns operates and there's not much to be gained by tilting the ETs to more than latitude plus 20 degrees or so. If you need to increase winter performance, it's better to install more tubes.

Posted Tuesday 7 Jun 2011 @ 10:14:55 am from IP #
micko
Member

Guys - the 15% reduction if E or W is based on using Polysun modelling program which is quite accurate and considers all the key relevant factors - but averaged over a year. The sun is high in the sky during the summer and so even in the afternoon a low angle East facing panel will still receive significant sunlight. So it does depend on the position on the roof and installation angle.

In the winter the impact of facing E/W would be greater as the sun is lower in the sky and so after midday the amount of shading on the panel may be higher.... would need to have a look at the actual collector in the afternoon to see if it is getting sun or not.

If facing North then installing at 15deg above latitude is normally of value as you maximise winter output and the reduction in summer is not enough to result in insufficient hot water as summer output is already more than required for most households. If facing E/W then installing at a higher angle would not provide much benefit and may even be detrimental. Many factors, and their impact change throughout the year.

Posted Tuesday 7 Jun 2011 @ 1:34:16 pm from IP #
swanning_it
Member

micko, can the Polysun program model E-W efficiency reduction for winter only?

Posted Tuesday 7 Jun 2011 @ 6:40:42 pm from IP #
micko
Member

I will get my Engineer to run the model.

Posted Tuesday 7 Jun 2011 @ 11:12:16 pm from IP #
cnheu
Member

@Gandini,

Just as some food for thought. The evacuated tubes, actually experience peak output at two peaks during the day, one before and one after. This is because of their passive tracking capability, such that at when the sun is OFF-centre more irradiation is externally reflected off other tubes and has a chance to be absorbed. Micko can confirm.

This maybe why it seems unintuitive, the evacuated tubes cannot be considered as a flat panel facing east. Additionally if you were to place the panels on a tilt mount, they can actually absorb from behind as well, another benefit of the simple geometry of the evacuated tube.

Having said that, I wouldn't rely on my calculations to make judgements about insolation. I'll be interested to see what Micko yields with his modelling.

@PeterS

I do hope everything with your system goes ok!

Posted Tuesday 7 Jun 2011 @ 11:37:59 pm from IP #
kesa32
Member

Hi PeterS , l'm finding it odd that your "top" sensor is so low in the tank..... my AAE 315L tank has the bottom sensor at around 200mm from the bottom and the top sensor around 200mm down from the top of the tank.
l just went out and checked it and the top temp is 62c , bottom 31c and the ET on the roof was pumping down at 44c............this is at 2.30pm
l got home from work this morning and the tank temp was 19C bottom , 64C top ,manifold 6c ( l get home at 7.30 am )...the bottom is usaully around 23C after a nights boost , but being sub zero overnight the pump would've been ciculating water from the bottom of the tank to stop freezing up on the roof, hence 19C temp
Water from our rain water tanks are running around 8-9C (roughly) for supply

My wife and son showered this morning after l read the unit and did dishes etc , so considering it's now 5c outside l'm pretty happy to be getting 44C on the roof......it's very cloudy , no sun anywhere( that l know of , as l was asleep ) and on and off light rain ( the pump[ has cycled roughly 50 times since this morning )
lt'd be ineresting to see how hot the ET's would get if the bottom tank temp was higher ( system works on around 12C? variance for the pump cycle )

Cheers Ken

Posted Wednesday 8 Jun 2011 @ 4:55:40 am from IP #
PeterS
Member

It looks like the Polysun software can be downloaded as a demo for anybody interested. I don't know what restrictions are on the demo. The promotional material says that weather data for a huge number of locations is available, and that manufacturer specific system models are available, so it wouldn't surprise me if Apricus systems are directly available. It also seems to indicate that hour by hour and month by month data can be looked at. I have no idea how easy it is to use though. Just letting you know if anyone wants to download it and play.

Posted Wednesday 8 Jun 2011 @ 5:13:06 am from IP #
PeterS
Member

Ken,

I checked last night, and my memeory was a bit faulty. The top sensor is pretty much right in the middle of the tank. I don't think it matters to the operation of the system, because it's the bottom sensor it uses to work out when to pump. I think the middle is pretty much level with the boost element, so there may some use in having it there. For most usage though right near the top seems to make more sense, because it will give you then some idea of what the temperature acually coming out of the tap is. Indeed, until pretty recently, we had used that sensor as a guage as to whether we should run the booster or not - as we assumed it was equivalent to the outlet temp, and therefore if it got too cold we needed to boost. In fact though, we can still have quite a lot of hot water left even if the "top" sensor is reading quite a low temp. Not really sure then why the top sensor is even there (although the one thing it does help with is that if the top sensor and inlet sensor both read the same, it is a pretty safe assumption that the entire tank is close to that temp all the way through I think?).

Posted Wednesday 8 Jun 2011 @ 5:40:36 am from IP #
kesa32
Member

Yeah l'm amazed at how much variance is in a hot water storage tank
lf we run the water right down and it's boosted overnight that gives us 23C bottom temp , 65/66C top temp, the booster element is about 1/3 of the way up the tank
l might have to build a tank enclosure as it's freezing outside now, the tank has dropped to 61C top, 28C bottom , and the ET is 29C and it's getting dark outside, all we've done since the last reading 2 hours ago is wash hands x 3 , so l guess that and a little heat loss at the tank as well as the cold water coming into from draw off of hot water
Can't complain though , it's still hotter overall than this morning ( apart from the top temp )and will need little boosting tonight

Posted Wednesday 8 Jun 2011 @ 7:25:54 am from IP #
Solgen
Member

Interesting observations regarding temperatures of the water at various points on the tank. In an standard HWS the hot water effectively "floats" on top of the cold water, as anyone who has experienced running out of hot water when showering, the change from hot to cold is very quick. In contrast my ET solar system has not shown that characteristic, as after a number of cloudy/rainy days the temperature each day gets lower but never cold. I was wondering is it because of the pumping action, the water is mixed and therefore the boundary layer may not form except perhaps after the pump has stopped.
My controller doesn't give water temperatures and so I have made a digital thermometer but am unsure as to where is the best location to place the sensor so as to get a realistic reading of the water temperature, any ideas?

Posted Wednesday 8 Jun 2011 @ 11:12:59 am from IP #
micko
Member

POLYSUN:

As requested I did the Polysun modelling of a system. It is 30deg installed in Sydney on North, NE, NW, E & W directions. Please see a summary of the results here:

http://dl.dropbox.com/u/103200/Due-North-Comparison.png

Note the average is roughly as I said, 15% annual difference... but the winter impact is much more considerable as the sun is low in the sky. Interestingly NE and NW actually provide MORE output in Summer, Spring and Autumn than due North due to the IAM curve of the tubes, but still less in the Winter.

So certainly for optimal Winter output, the direction is very important. We have only recently obtained this new version of Polysun but it is proving to be very useful. Other software we have used in the past has been unable to provide such a clear comparison and compare the key factors.

STRATIFICATION & TEMP SENSING

The "top" sensor is there to monitor the tank temp for protection, shutting down the pump once the temp reaches a suitable level. This is best located in the middle rather than the top. WHY? If you have the sensor right up near the top and there is 70oC water in the top 1/4 of the tank and the rest is cold (after some showers) the controller would still not allow solar to come on. But located in the middle, it will know that in reality the bottom half of the tank is cool and so solar contribution can occur. Yes of course if only the bottom 1/4 of the tank is cold the problem will still exist... but we can't have 10 sensors up and down the tank.

Sensor location is quite important in terms of ensuring optimal system operation and if you have a Apricus Glass Lined tank (which is customised to our specifications) you will find the sensor locations are about 400mm up from the bottom for the bottom sensor, roughly half way between the solar flow and return ports and the "mid" sensor, as it should really be called, is mid tank level. Based on a lot of testing we have found those to be the ideal locations.

Posted Thursday 9 Jun 2011 @ 2:17:55 am from IP #
PeterS
Member

Solgen, I might be wrong about this, but this is what I am thinking. The tank will be insulated, so just slapping a thermometer onto the tank will be useless. If the tank has some ports in it for sensors, then you may be able to use those, as there will be a hole in the insulation at that point - although if those ports are in use by your system then you may not be able to access them. The pipes though will be copper, and copper transmits heat pretty well, so I would imagine that measuring the external temperature of the pipes would give you some idea. For outlet temp I would be tempted to tuck the thermometer down between the pipe and insulation and leve it there for a bit. I could be wrong, but I imagine that will give a good sense of outlet temp. I think the small section of pipe that joins the overflow pressure valve to the tank will be at about that temp too. Doing the same thing but for the inlet pipes will tell you your cold water inlet temp. I would try it and see if the results you get make sense. You can also compare your results with the actual measured temp of water coming out of the tap and see how it compares.

I too think that the pumping action tends to mix the water in the tank to give a consistent temperature all the way through. If you are using hot water without the pump going (showering at night or early morning for example) then I would still expect the layers to form in the tank as you use hot water though.

@micko - that makes sense why the upper sensor is in the middle. I was sure there must be a good reason, but couldn't for the life of me work out what it was. That makes sense though, thanks.

Posted Thursday 9 Jun 2011 @ 2:19:02 am from IP #
kesa32
Member

Hi Solgen , yeah the solar mixing in at the bottom would definitely help , as to your placement of the DMM probe , l guess you could test the inlet and outlet points where they enter the tank's skin or where your current sensors are located for your controller, it'll be a guide ,you'll have to insulate the probe as best as you can to get some sort of an idea....

Posted Thursday 9 Jun 2011 @ 2:25:26 am from IP #
micko
Member

TANK MIXING

The tank will mix between the solar flow and return ports... it won't mix the water above that very much unless the flow rate is very fast (which normally isn't) OR the tank is all a similar temp. IF the top of the tank has 60oC water and the solar return is only 40oC that won't readily mix... the action of stratification (hotter floating on cold) is very strong.

To understand this better: Pour cold water gently down the side of a cup that is already half full with hot water... the two will form layers. You can stick your finger in and feel the two layers clearly defined, and when you drink you will find the cold slides down underneath the hot and you can clearly feel two different temperatures.

Taking a reading of the copper pipe close to the tank under the insulation is valid, but add around 5oC to the value to account for the heat loss etc if the temp is much high than ambient temps. Make sure you are getting good contact.

Depending on the sensor port design you may also be able to temporarily pull out the sensor to insert your probe... Do this at your own risk, as each tank and sensor port design may be different.

You can test the top of tank temp by gently easing the lever on the PRTV and measuring the water that exist the drain pipe. CAREFUL IT WILL BE HOT!!!

If you just completed a few showers, then immediately tested the flow out to the collector you should find that is pretty cold. But cold temp are very easy for the ET to raise as solar collector performance is highest when the water is cold - and so will quickly be raised from "cold" to "warm"... hence rarely seeing low temps in the bottom.

Posted Thursday 9 Jun 2011 @ 2:34:20 am from IP #
PeterS
Member

Micko, I tried to look at your dropbox link for the comparison, but didn't see anything - just a small grey box.

Posted Thursday 9 Jun 2011 @ 3:05:40 am from IP #
Lance
Key Master

Works for me...

Posted Thursday 9 Jun 2011 @ 3:32:44 am from IP #
PeterS
Member

OK, I'll try later from a different computer. Thanks

Posted Thursday 9 Jun 2011 @ 3:38:39 am from IP #
PeterS
Member

Alright I saw it, and the winter difference is nearly 50% for east vs north facing (in SYdney). That's a fair bit of difference. I have no idea what it would be for a Brisbane latitude, although my gut tells me the difference may not be quite as big. but I am guessing it would still be fairly large. I will definitely be talking to our installer about what his favourite beer is and investing in that carton.

Posted Thursday 9 Jun 2011 @ 6:49:23 am from IP #
bgraetz
Member

@micko

Great Graph, i've always thought and worked off the average efficiency drop of the 15-16%.

Question -
Was that PolySun model specifically on the Apricus collector output?
or just working off direction/angle/energy from the sun in general?

If it was specifically Apricus, then is it possible to run a calculation for a flat panel system? because i would thing that the E/W Direction output would be even more severely affected than the tubes. Interested to check the differences.

I understand if you don't want to, incase it looks bias etc.

I know a few people who work at the local Tafe training plumbers, and will send this graph & program info through to them, because I'm sure they work off the 15% average yearly but to me direction should be take a lot more serious than it currently is.

Also will forward to any plumbers etc. that i know are installing solar hot water.

Posted Thursday 9 Jun 2011 @ 11:00:47 pm from IP #
kesa32
Member

Yes Peter, if you can get it done for a slab then do it, might as well get it on the right angle hey
i'm tempted to add another set of ET's if i could get 'em at the right price , then cover them over in the summer months as the weather here a lot of the time is overcast

Posted Friday 10 Jun 2011 @ 7:38:01 am from IP #

RSS feed for this topic

« Previous 1…91011 12 Next »

Reply »

You must log in to post.