Solar Experts Needed.

sundodger5

To cut a Long story short. had sei out to look at my solar install as i had questions regarding efficiency. The system was producing nowhere near what i was told it would.
Turns out that the thing is plumbed backwards.
The feed to the panels comes out of the middle of the tank and returns to the bottom.
Any idea as to what the effect this has had on running cost/hot water production of the system etc?
Thanks

sydthebeat

strange one... im not a plumber but ill give it a shot...

as cold water falls, the outlet back to the panels should be at the bottom, therefore the hot inlet is heating from below but the cold outlet is above so its both heating and cooling at the same time.... therefore the 'real' temperature exchange is somewhere arond half that between the inlet temp and outlet temp...

if it was the right way round, the exchange temp would be higher, in theory,

also as cold ater falls, theres a natural circulation through the system, where as now the pump has to work a bit extra to circulate the liquid...

was this installed by an SEI approved installer???

sundodger5

Yep Approved installer hence the sei inspection at my request. i knew i had problems but this has put the icing on the cake.

quentingargan

Having the plumbing the wrong way around at the cylinder may reduce the efficiency, but only marginally. In fact, there are some authorities on the subject who prefer to show the circuit that way around - the thinking being that the hot water hits cold water at the bottom of the cylinder and loses its heat at that point, but I don't believe that this is the case, and I would get the installer to reverse this.

However, I don't think this is your only problem. I'd need more info, which you can PM me if you like - type and size of panel (tube or flatplate), size of cylinder. Towards the end of a sunny spell, let me know what temparatures the controller is showing at the panel, top, and bottom of the panel (I am assuming that your controller has two probes in the cylinder - let me know if not).

Is your installer still on the SEI list? They may not have bothered to do the training which was only required after March last year.

quentingargan

Just a few more things - If you have a flowmeter (usually in the pumpstation) can you check the flow rate while the pump is running?

Is the pressure normal in the system? (usually 1 to 2 bar)

Is the insulation intact on all the solar pipework circuit (you shouldn't be able to see any copper or brass the entire length of this circuit)

Are the other pipes coming from the cylinder insulated (central heating, hot water outlet etc.)? - this is a common failing - the central heating pipes are bare as a baby's butt and heat generated by the solar circuit is simply lost through these pipes)

Q

1922

lads how long do solar panels last? i'm debating putting them into a new build...but wondering are they worth it??

quentingargan

1922 wrote: »

lads how long do solar panels last? i'm debating putting them into a new build...but wondering are they worth it??

Vacuum flasks and tubes will lose their vacuum after about 20 years and at that stage you would need to change the tubes of flasks. For flasks, this isn't too expensive - less than €5 each. For tubes it can be a lot more expensive as the heat pipe is an integral part of the tube.

Flatplates should last 40 to 50 years.

In both cases, this is provided you put in a heat dump to get rid of surplus heat. Overheating can substantially shorten the life of a system.

In a new build, it is well worth doing - the payback time is about 10 years, because you are already fitting a cylinder, and can simply put in a solar one. You already have scaffolding on the roof, etc., and the plumbing is a lot easier during construction.

I run courses for DIY installers. If you are interested, send private message.

1922

quentingargan wrote: »

Vacuum flasks and tubes will lose their vacuum after about 20 years and at that stage you would need to change the tubes of flasks. For flasks, this isn't too expensive - less than €5 each. For tubes it can be a lot more expensive as the heat pipe is an integral part of the tube.

Flatplates should last 40 to 50 years.

In both cases, this is provided you put in a heat dump to get rid of surplus heat. Overheating can substantially shorten the life of a system.

In a new build, it is well worth doing - the payback time is about 10 years, because you are already fitting a cylinder, and can simply put in a solar one. You already have scaffolding on the roof, etc., and the plumbing is a lot easier during construction.

I run courses for DIY installers. If you are interested, send private message.

thats sound. i really dont trust myself to do it though!!!

sinnerboy

1922 wrote: »

lads how long do solar panels last? i'm debating putting them into a new build...but wondering are they worth it??

For a new build you will have to put in some form(s) of renewable energy - can be a one or more of

- heat pump / solar thermal / wood pellet stove or boiler / wind turbine or solar pv

sundodger5

First thanks for the pm

quentingargan wrote: »

Just a few more things - If you have a flowmeter (usually in the pumpstation) can you check the flow rate while the pump is running?

I have not checked this will come back to you

Is the pressure normal in the system? (usually 1 to 2 bar)

No keeps losing pressure has had 3 attempts to fix. Currently at around 0.25 bar.

Is the insulation intact on all the solar pipework circuit (you shouldn't be able to see any copper or brass the entire length of this circuit)

Has insulation missing in spots where pipework was pulled through nothing major though.

Are the other pipes coming from the cylinder insulated (central heating, hot water outlet etc.)? - this is a common failing - the central heating pipes are bare as a baby's butt and heat generated by the solar circuit is simply lost through these pipes)

Has insulation but it is the grey stuff not the black insulation on the solar. i have also wrapped this with airflex for addded comfort

Q

will come back to you via pmfor other info you asked for.
thanks

rayh

sundodger5 wrote: »

To cut a Long story short. had sei out to look at my solar install as i had questions regarding efficiency. The system was producing nowhere near what i was told it would.
Turns out that the thing is plumbed backwards.
The feed to the panels comes out of the middle of the tank and returns to the bottom.
Any idea as to what the effect this has had on running cost/hot water production of the system etc?
Thanks

I would confirm some of the previous contributions with respect to the orientation of the pipe at the tank, but a possible contribution could be if the flow through the panel was incorrect.

Dixy

This may sound stupid but i have seen it happen....

When you say the its piped out the bottom and in the middle of the cylinder, are you sure they are the same coil?
A solar coil is a very compact unit and the conection's are normally no more than 200 to 300mm apart. Current Albion models from Coppercraft have the solar coil in and out at the same height with a double twist coil.

sundodger5

I would be surprised if the coil is close on this baby. its a 1500L buffer tank.

Evergreen

sundodger5 wrote: »

I would be surprised if the coil is close on this baby. its a 1500L buffer tank.

1500L buffer tank - I have never seen a buffer tank of that size that does not have the solar coil in let and outlet side by side. Are you sure that this installer has not just plumbed the solar circuit striaght into the main body of the buffer tank? If he has that is ok so long as the controller is set up to re-circulate water through the panels when the out door temperature drops to freezing or below.

Also, what size panels do you have installed? For 1500L you are going to need about 15 sq meters to have any kind of impact on rasing the heat.