Solar Panels - Are the new glass tube type any good?

[compass]

Hoping for any feedback re these new style of water heating panels over the old tried and trusted type.

I need to replace my ones soon, so any advice would be very welcome and may be of interest to others.

I suspect the new style are more efficient but how long do they last??

Thanks in advance

Compass

[jock2]

Yes had one for a couple of years now no problems even today hot water bubbling out

[jimm]

check to make sure that they can withstand the pressure of your pump or the mains water.

[MikeK]

if you are replacing your hot water cylinder at the same, time I would strongly advise on getting a system that incorporates a stainless steel hot water cylinder. The galvanised steel cylinders widely used here have a life expectancy of 4/5 years if on a pressurised system, maybe a bit longer if not pressurised. This will be less if you are using well water. I got this info off the firm that I bought my last one off, three years ago. it has now started to leak!
The "New type" are called Solar evacuated tube (google for further info on how they operate and compare). Solar Evacuated tubes will work better than the flat bed type, in cloudy / overcast conditions.

[MikeK]

Yes had one for a couple of years now no problems even today hot water bubbling out

Does your cylinder have an immersion heater installed, if so do you need to use it during the winter to top up the hot water?
What is the make of your system?
Many thanks.

[pakora]

We have had one for a couple of years, We are only here during the Christmas New Year time in the winter and usually it is ok. This year it needed a bit of a top up from the immerser. but that is because of the lack of sunshine. Last year it was fine and Easter is no problem

[compass]

Hi Jimm

You make a very valid point about pressurised systems - as the more I read about these evacuated tubes the more I find they are suitable for "open atmospheric systems" or "very low pressure" ones.

The standard pressure release valve used out here on a typical pumped house system (like ours) is 3 bar ( approx 44psi)!!!!

The much more expensive "heat pipe" tubes are more suitable but don't know if they're even available here, will investigate.

I have noticed quite a few blown/ milky coloured tubes on various roofs and wondered why - this may well be the cause?

C'pass

[jock2]

Yes had one for a couple of years now no problems even today hot water bubbling out

Does your cylinder have an immersion heater installed, if so do you need to use it during the winter to top up the hot water?
What is the make of your system?
Many thanks.

The make is Kuzimak they are made in Turkey,yes there is immersion heater fitted into the tank.used the immersion about 3 times so far this year long as it's not completely cloudy you have hot water , today for example the water was hot enough for a shower by 9 am

[Jonnie]

What about photocoltaic? Anyone got some price comparisons?

[kibsolar1999]

well, Jonnie... good question....

the advantage of PV is that you can use the power in times of "no (or less) need" (to produce hot water, eg, in summer) to feed the grid.
( i refer here to so called "net metering" systems for private homes)

if you, say, use your immersion heater for (in average) 1 hr a day, then you come to 365 x 3 kW = 1095 kWh per year.

1095 kWh represent approx 0,7kWp of the "harvest" of a solar PV installation only and would cost you, "hidden" in a eg, (in total) 4 kWp system, approx 1000-1200 euros and your worries about "dripping solar heat pipes", not proper working "flat collectors" or "broken (milky coloured... the vaccum is gone... no function any more..) vaccum pipes and glasses" are over.

if you need much more hot water, then the case might be different... we have always solutions...

kibsolar1999

[kibsolar1999]

cont...

there are two different kind of "glass (vacuum) tubes" available.
1. the "flow through" ones
here the water (to be heated up) flows direct through the glass tube. often used in "open systems"
2. the "heat pipe" ones, where a "medium" flows internally in the pipe and the heat is "transferred" into the storage tank through, eg, a "manifold".
the system often is "closed" = solar cycle and storage tank is seperated from each other. the better choice. more expensive.

not to forget that even the best DHW solar collector system can not always be sufficient, eg, in cloudy, rainy conditions (for several days...)
so, from time to time, you need the immersion heater to achieve the "required temperature". these are additional costs and you can lower your bill , say, by 80% , not 100%. this you have to add to the price for a glass tube system ( or subtract from the price for a PV system )

conclusion:
- calculating your energy needs for hot water with a "PV- replace calculation" is safe. you know what you need and replace it with solar power accordingly.
- no or much less installation efforts, PV is the more reliable technology...
- PV may ( 3 or 4 or 5 kWp) cover other electrical energy needs as well, eg, air cons, pool pump.. this kind
- no dripping solar pipes, no or less mechanical failures (on some of the PV panels you can walk)
---- PV is the better solution.

kibsolar1999

[Sewage]

Had ours done 2 years ago highly recommend it

[kibsolar1999]

Hi (Sewage),

- what system you have (open, closed) and which manufacturer? Kuzeymak?
- and how much did the full installation cost? as,
question here was also the price comparison = the energy needed to produce the needed amount of hot water vs the production of hot water with solar.
here we need to start with the question of "efficiency" for a solar DHW system.
"theoretically" a solar hot water system is nice.. but for comparison you have to deduct all losses as well.
a 3 m² solar water collector can produce up to 3300 kWh a year. eg, thats 3 times more then PV.
but,
- eg, if i do not use the produced hot water today, the water is hot already for tomorrow = one day of solar production is "lost".
the worse case is: what do you do with all the hot water in summer?
during the 4-5 month in summer, 70% of all the (theoretical possible) energy is produced and you use max 10% (?).
or: yes i have a solar DHW system, but it always takes 20 liters until i get hot water...
(do i use my hot water for the washing machine?
if not, you need electricity for the washing machine although you have a solar DHW heater...)

due to all losses, you get a max 30% out (of the theoretical possible) of your (good) solar DHW heater (the old style cypriot system are completely waisted money), even for those living here permanentely...
plus, you have the risk of failures. eg, the post ".....hot water bubbling out..." is not "good", it is something you should worry about...

for all which are not permanentely in cyprus, a solar DHW heater is more then doubtful, no matter what system.
good solar DHW heaters are only good for appartements, where you do not have space for PV installations.

to our opinion the best way to go for "solar and energy saving investments" are, in this order:
1st, install a net metering PV system to cover all electric needs, incl the hot water,
if you have more requirements:
2nd, get a solar pool pump (savings approx 2.000 kWh a year for a 10 x 5 pool)
3rd: install a good solar DHW heater (previously estimated to 1.100kWh per year.)
(or.. you invest into a bigger solar HW system which combines DHW, pool and central heating...)
4th: in between and just by chance, invest into a good inverter runned aircon, a better A+++ fridge, this kind of energy savers.
note: if you invest to energy savers at first, you reduce your electricity bill and may then only to be permitted to installa smaller PV system...
see http://www.kibkomnorthcyprusforum.com/v ... 45&t=36206

Regards
kibsolar 1999