I am in the process of installing a solar HWS. I am attracted to the evacuated glass tube collector system but a number of installers have stated that the tubes are not strong and break very easily. Not surprisingly it is mainly companies that supply flat panels that have said this.
I would be very interested if any of the subscribers to this forum would care to comment on their experiences with solar HWS and in particular with the durability of the collectors.
Reliability of Solar HWS
(90 posts) (26 voices)-
Solgen
MemberPosted Monday 3 Nov 2008 @ 10:03:02 am from IP # -
Sunshine
MemberI have just had a Hills Evacuated 30 Tube/315L/ electric boost system installed a week ago. I am very happy with it's performance so far. The testimonials on this website http://www.bfasolar.com.au/testimonials.htm from very happy users of the evacuated tube system are very convincing that this new generation solar hot water collector is superior to the old style collectors.
I believe with the evacuated tube system you shouldn't need to use electric boost, going by the testimonials.
I was told by several companies who quoted me on the Hills that is a fairly rare event that a tube or tubes will break. I think they told me they had to replace the odd tube or two, but nothing major. Cost per replacement tube was around $50. I was told it takes pretty big hail or a cricket ball to break them. My house insurance has an excess of $100, so a tube or two won't be worth claiming.
I believe with the evacuated tube system you shouldn't need to use electric boost, going by the testimonials.Posted Tuesday 4 Nov 2008 @ 12:33:17 pm from IP # -
Anonymous
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Posted Saturday 8 Nov 2008 @ 10:41:19 am from IP # -
Solgen
MemberI took the plunge and installed a solar tube HWS. Very impressed with the performance, I have noted that here in Sydney it starts supplying hot water around 7am and is still operating to around 6pm (even though the sun is hardly on the collectors). My only concern is that perhaps the system we have bought (315l) is too large for 2 people as the TPR valve operates most days and we lose a couple of litres of water. I measured the temp of the tank water at 85deg C on a hot day recently. Unfortunately, by regulation the output has to go through a tempering valve which reduces the water temp to 50deg C. OK for showering but not too good in the kitchen. Other than that we are happy with the system, electric boost element has not been switched on, admittedly it is mid summer and should be the best time for a solar system.
Posted Sunday 21 Dec 2008 @ 12:40:27 am from IP # -
Sunshine
MemberYes the Solar Tube HWS are very efficient. I have observed it pumping hot water into the storage tank on a dull rainy morning. Quite amazing.
We have a 315L for 3 people in Brisbane, I agree probably overkill as well, but that extra capacity will no doubt come in handy in winter.
One way of reducing the loss of several litres of water every day, is to connect your dishwasher to the hot connection, instead of the cold tap, and select a cooler program. This way the dishwasher doesn't need to use electricity to heat the water, and hence there is an extra 22 litres of hot water being used every day by the dishwasher, and also saves 800Wh per cycle, which is around 300kWh per year saving. I believe it has helped reduce the purging from the TPR valve.
I would check that the hot water being supplied is at 50 degrees, as our system also has the tempering valve installed, and the water is hot enough if we wash up by hand in the sink.Posted Sunday 21 Dec 2008 @ 9:59:44 am from IP # -
Sunshine - can you give me an idea of the cost of such a system? I like the idea of evacuated tubes but the prices I have seen have been over $6k. Without access to the rebates due to our existing gas storage system these prices are too high to be competitive with the older flate plate designs.
Posted Monday 12 Jan 2009 @ 6:25:24 am from IP # -
Sunshine
MemberMunter-
I went from gas storage to Hills evacuated tube, so I missed out on the $1000 Federal rebate as well.
However the Brisbane City Council had a $400 rebate, plus Hills had a $400 cashback last October (which wasn't advertised, the salesperson just advised me at time of the quote).
All in all I paid $4809 installed after rebates, for a 30 tube, 315L stainless steel ground mounted tank.
Electric boost is permanently off. Even if I run the spa bath, still never run out of hot water, where the gas boosted 170 litre system would run out. I also run dishwasher now off hot water, further saving power costs.
I have observed it pump hot water off the roof even on a gloomy rainy morning, so I am very happy with the efficiency.
My sister used to have a Solarhart up at Ingham in Far North Qld, and even with only a small family of 2, she used to have to use electric boost in winter, so the flat plate ones to me probably aren't worth it.
A friend of mine has a flat plate Beasley in Brisbane, and he has to use electric boost after several days of rain or overcast conditions.
The testimonials listed at http://www.bfasolar.com.au/testimonials.htm I certainly agree with.
Shop around, some quotes went up to $6000. It's a quality system with stainless steel tank, with much better efficiency.
You may be able to get a flat plate SHWS installed for say $3000, but it is less efficient, so you will need to boost more (about $1 per boost in electricity costs) plus chances are the tank is made of vitreous mild steel, which means extra cost of anodes and tank won't last 20-25 years of a stainless one.Posted Monday 12 Jan 2009 @ 7:00:53 am from IP # -
Yes - I'm definitely keen on a stainless steel tank. I think I'll use the list in the current ReNew to find the cheapest evacuated tube, stainless tank, gas boost system.
From looking on-line some systems seem to be fitted with the Bosch 21e or 26e system. Online reviews of these two are not entirely positive. Does any one here have experience with these boosting systems?Posted Tuesday 13 Jan 2009 @ 1:57:02 am from IP # -
Sunshine
MemberI know a gas boosted system is another $800 or so extra over an electric boosted system.
Depending on which state you live in and how many in your household, it may be better to go electric.
Also, it depends if you have gas stove/oven in the house. We had no other gas appliances in the house, so I couldn't justify paying $40/quarter gas line rental for something that I may never need.
So far, no boosting at all has been required.Posted Tuesday 13 Jan 2009 @ 3:03:18 am from IP # -
I'm in sydney and have gas for heating, water and cooking already so gas boosting seemed logical. The connection charges a drag though. Same with electricity - in fact I just wrote a post about it on my blog (sorry for the blatant self promotion)
renovations08.blogspot.com
Cheers
Posted Tuesday 13 Jan 2009 @ 6:12:23 am from IP # -
Solgen
MemberMy system after rebates cost $3778, I saved a $150 by doing the wiring myself. I have turned off the booster and we haven't looked like running out of hot water, in fact the TPR valve on most days is releasing around 1-2 litres a day. For a 2 person household a 315l system is probably too big - or at least it is over summer! Admittedly, if a solar HWS doesn't work correctly at this time of the year then it never will.
The real test will be in winter if we get a week of rainy weather.
While gas boost is more environmentally acceptable, the small amount of boosting required plus the embodied energy in the gas booster may make electricity a better alternative - it is certainly simpler.Posted Thursday 15 Jan 2009 @ 7:14:22 am from IP # -
fliss2
MemberWe have an Edwards(stainless steel) flat plate system,(tubes were not quite in when we bought it)
in shade 50% of day, more than adequate hot water, we have only hooked it up to off-peak for boosting, and this has cut in after more than 3 days cloudy weather we notice. Being offpeak it is easy for us to see when this has happened.It seems to be an efficient SHW unit as it is always overflowing with water which has to be steamed off, so our next job is to divert this back down the gutter back into the rain water tanks.
Posted Monday 26 Jan 2009 @ 6:43:06 am from IP # -
fliss2
MemberWe also bought a Miele washing machine which uses 56L water but which has both hot and cold taps, (most machines only have cold tap which requires washing machine to heat up the water)
by allowing the washing machine to have the hot water tap it uses up more hot water - which we seem to have plenty of - have never run out. (family of 3-5 + visitors+++)Posted Monday 26 Jan 2009 @ 6:45:13 am from IP # -
questionman
MemberI was initially quoted with $4200 net which was unit cost plus installation less federal rebates, RECS and state rebates, by Apricus for a 30 tube, 315 liter stainless tank, gas boosted with 26 liter Rinnai, but after attending the Perth Home show and talking to the Apricus agent (who has my deposit) and stupidly mentioned to him that another Apricus agent was charging $2500 just for the installation, This Apricus agent whom I spoke to and paid my initial deposit to, changed his mind and told me the next day, that the initial quote was wrong; that they would have to look at my gas connections again to see if they can give that initial quote. He said I would need a 20 mm gas pipe connection and not a 15 mm pipe; he sent his plumber to my home the second time, to check my gas (pipe connection in the front of my home. I have a 20 mm main gas pipe connected at the front of my home, to which my gas stove's and gas heater's 15 mm gas pipes are connected. After looking at this, the plumber still insisted that I have to pay extra for installation ( more than the initial quote), because he said the gas pipe extension has to be routed above my door ( in a round about way) and has to go through my carport at the side of the house to reach my water tank location at the back corner of my home. He said that routing a gas pipe under the door is against best practice. But all of these had already been checked by him and another 'employee' the first time they came to check my place before the initial quote. I find this very unpleasant and frustrating so I decided that something had went wrong which could be related to my inadvertent mentioning of the other Apricus agent's expensive installation charge. So I decided to withdraw from my intention to buy the solar hot water system from them and get a refund of my initial deposit.
Not only that, during the Perth Home show, when I wandered into the Other Apricus agent ( with the expensive installation charge, I was rudely dismissed by this agent who told me " why are you here? there, you caused me to miss a customer". This happened even before I went to the Apricus agent's stall ( who had my initial deposit) and told the latter of the first Apricus agent's expensive installation charge. I dont know why I have to be treated this way, just because I was enquiring around to look for the most reasonable/best price which I can afford in my situation. I see no reason why I should be treated this way. Are not people entitled to asked around to look for the best prices/best products before they buy? whether they are financially well-off or poor?.
The plumber kept on pushing for an electric boosted solar hot water system for me even when I told him I want a gas boosted one. At present I have an electric storage heater at the back corner of my 2 story old unit of 50 square meters and 2-3 people in the home with a 20 mm gas pipe connection at the front of the unit. I want a gas boosted one because I anticipate that in my old age, I will have a limited income and want to minimize the utility bills to the max. At the moment, I dont feel like pursuing this evacuated tube solar hot water because of this recent unpleasant experience from Apricus agents.
Posted Tuesday 27 Oct 2009 @ 6:07:08 pm from IP # -
Sunshine
Memberquestionman,
sounds like you had a bad sales experience.
I believe with a 30 tube model with 315 litre storage tank with only 2-3 people living in the premises, you shouldn't really need to boost at all.
We have a Hills Evacuated tube system, same size in Brisbane, family of 3, and in the 12 months since install, haven't required boosting.
An electric boost model is around $850 cheaper than a gas boost when I was looking around.
As I wanted to get away from paying gas line rental of $45 a quarter for something I may not ever need, as i have no other gas appliances in the house.
Maybe look at the electric boost option, it will be cheaper to install, and for your size system, boosting should be very minimal.Posted Tuesday 27 Oct 2009 @ 9:57:33 pm from IP # -
dymonite69
MemberSunshine,
Your claim that 30 tubes can heat 300L of water in a Brisbane winter seems overly optimistic. You either have 50% more sunshine than stated in the Bureau of Meteorology data or you are using only 2/3rds of your tank capacity.
From first principles:
Brisbane winter 3.36 kWh/day of solar insolation
30 tube aperture area = 2.84 m2Total amount of energy collected = 3.36 x 2.84 = 9.6 kWh
But you need more than 15 kWh of energy to heat 300L of water from 13 deg C to 60 deg C. *
* Specific heat of water = 4 kJ/litre/Kelvin (or 0.011 kWh/litre/Kelvin)
Total energy required to heat 300L = 0.011 x 300L x 47 degrees = 15.51 kWh
Note this is assuming that you can convert 100% of available sun into heating energy - which is impossible. Most evacuated tubes don't exceed 80% in efficiency.
Posted Tuesday 27 Oct 2009 @ 11:23:41 pm from IP # -
Sunshine
Memberdymonite69,
Your figures are way off the mark.
Hills recommend a 22 tube system with 250 litre in Brisbane for 3 people.
I wanted extra generating and storage capacity to reduce the instance of boosting.
If I have an oversized system, larger than recommended by the manufacturer, how can it be "overly optimistic" for it to supply enough hot water??..
what a bizarre claim you make!!
By the way, Brisbane water temperature isn't 13 degrees, not even in winter.I'm not sure where you got these figures from "Brisbane winter 3.36 kWh/day of solar insolation", but during winter my solar PV system was averaging 15kWh per day from a 3kW system..
We run an efficient household, our water use for 3 people is around 160 litres per day.
I know the dishwasher uses 22 litres of hot water per day. Showers may use another 40 lites, so we are using probably around 60-70 litres of hot water per day. So a 315 litre system will last for days.
Another point, the hot water system heats water up to 95 degrees, so hot water use is reduced further, as more cold water is mixed with the hot, to get the desired temperature.
We had 4 days of solid rain in May, only on the evening on the 4th day did I notice when having my shower, that I needed a bit more hot water. If we had another day of rain, boosting would have been required, but the next day was sunny, and hence didn't need to boost. That was the only time I got close to requiring to boost.
I must also add that the solar hot water collectors are facing west on a fairly steep 40-45 degree angle, far from being optimally positioned, but work neverless fine.Posted Wednesday 28 Oct 2009 @ 12:43:33 am from IP # -
ghostgum
Memberdymonite69's figures are correct, but as was written you are probably using 2/3 of the tank capacity. I've seen the temperature logs from a friend's solar hot water system, and it is clear that only part of the tank volume is used each day, and the tank gets hotter with several successive sunny days.
3.36kWh per square metre is probably derived from the strong solar sun figure of 4.2 hours for Brisbane in winter * 800W per square metre.
http://www.yourhome.gov.au/technical/fs67.html
Sunshine's point about cold water not being 13C may be fair, but changing this to 20C in the calculation only makes a small difference.Posted Wednesday 28 Oct 2009 @ 2:20:36 am from IP # -
Sunshine
Memberdymonite69 was claiming that I had said a 30 tube system can heat 300 litres of water in a Brisbane winter.
I never made such a claim.
I am advising that a 30 tube, 315 litre evacuated tube system for a household of 3, is very adequate for supplying hot water with no/ very limited boosting.
Obviously if a household is using 200 litres of hot water per day, then they would need to boost at times if weather is not optimal.Posted Wednesday 28 Oct 2009 @ 3:03:43 am from IP # -
Sunshine
Memberdymonite69's figures are not correct..
Hills website claims 97% thermal efficiency with evacuated tube system
http://www.hillssolar.com.au/arbitrage/pages/77A 30 tube system has collection area of 4.97m2 not 2.84m2
http://www.hillssolar.com.au/arbitrage/pages/110/Hills_Solar_SS_EB315_09.pdfSo, Total amount of energy collected = 3.36 x 4.97= 16.69 kWh
Winter water temperature 19 degrees.
Specific heat of water = 4 kJ/litre/Kelvin (or 0.011 kWh/litre/Kelvin)
Total energy required to heat 370L = 0.011 x 370L x 41 degrees = 16.69 kWh
So figures suggest system can produce 370 litres of hot water, raising it from 19 to 60 degrees in winter.Either way, system works fine in the real world, not just in theory.
Posted Wednesday 28 Oct 2009 @ 3:25:56 am from IP # -
ghostgum
MemberAre we talking about the efficiency of collector itself (97%), or the efficiency of transferring sun energy to the water in the tank? I've got no information on the latter, but I am sure it will be lower than 97% (due to loss in the manifold and pipes down to the tank).
That PDF you reference gives the 30 tube collector aperture as 2.844m2. I didn't take any dymonite69's figures for granted - I checked them all! I estimated a 30 tube collector as 30 x 0.05m x 1.8m = 2.7m2.
dymonite96's figures show that after installation, a cold tank will take two average winter days to heat up. As we all know, we don't usually use a full tank of hot water each day, otherwise someone gets a cold shower and the hot water hog gets chastised.
Posted Wednesday 28 Oct 2009 @ 3:59:26 am from IP # -
dymonite69
MemberGhostgum points out correctly that the aperture area (the actual solar absorbing portion) is about 60% of the collector area (the dimensions of the unit).
If you look at a standard collector, the tubes are not packed next to each other.
Efficiency is measured by the amount of actual water heating energy divided by the solar radiation energy.
There is no device (let alone a solar HWS) that can achieve such a high efficiency. There are energy losses both from the collector and the associated plumbing.
The 97% figure is misleading - but that's marketing for you.
Posted Wednesday 28 Oct 2009 @ 5:03:49 am from IP # -
dymonite69
MemberSunshine said,
I'm not sure where you got these figures from "Brisbane winter 3.36 kWh/day of solar insolation", but during winter my solar PV system was averaging 15kWh per day from a 3kW system..
In reply:
Bureau of Meteorology - solar insolation for Brisbane Regional Office:
I am not sure what your point is about the 3 kW PV system in relation to a solar HWS. Their efficiencies don't even compare.
3 kW refers to the power output (assuming best case conditions e.g. full sun, ideal inclination, maximal efficiency which is around 20% for conventional PV - more likely 15%). Total energy output is a function of the time that the collector is exposed to sunlight.
A 3 kW system has about 20m2 of collector area. Potential energy collected is 20m2 x 3.36 kWh/m2/day = 67.2 kWhr/day. Only a fraction of this can be converted into electricity.
Posted Wednesday 28 Oct 2009 @ 9:42:04 am from IP # -
Greenozi
MemberIt is sad, that inflated prices cause so much hassle you all. I have been selling 30 tubes all SS HWS at $900 and 60 tubes collectors at $1200.For DIY installation. Still making nice profit. Cost of HW equipment is marginal and anybody could have more hot water that possibly could eat. Thanks to government donation 3 to $4.000 cost is the norm now and everybody quarrel about extra tube they can afford. Sun is free, HWS almost too, the only question remains how much hot water family really needs? There was one educational lesson to my teenagers when using solar water. The first person in the queue could use whole cylinder however big it is and the rest of family had cold one. Mayby that is why nowadays our family uses 1/3 of Melbourne average (water)?
Posted Wednesday 28 Oct 2009 @ 10:54:50 am from IP # -
questionman
Memberwhat is the use of government rebates and RECS, if the suppliers/installers are jacking up the prices of solar hot water system with same amount or even more? It still is too expensive to middle to low income australians who needed the solar hot water systems to reduce their electricity/gas bills which comprise a big chunk of their living expenses.
Posted Wednesday 28 Oct 2009 @ 12:09:47 pm from IP # -
Sunshine
Memberdymonite69,
The problem with under engineering a system, typical behaviour by some sales people to sell you the cheapest item just to get a sale. It may not be designed to deliver what is required by your usage, then solar hot water systems get a bad name, as systems need to be boosted daily.
There are some discussions in the forum about some systems requiring boosting each night after everyone has their shower. What's the point of doing that? Obviously a system too small for their use.
That means next morning when the sun comes up, system has no further heating to be done by the sun (as it already has been gas or electrically boosted), so really it negates the whole reason of having a solar collector.
System should have enough spare capacity to cater for showers for household members the next morning without requiring boosting overnight.
Hence it is critical to not under engineer, otherwise you might as well just remove the solar collectors, as regular overnight boosting makes them redundant.Posted Wednesday 28 Oct 2009 @ 2:01:34 pm from IP #
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