Savings from solar installation

pod2011

Hi,
Can anyone give a before and after installing solar water heating, cash savings on esb bill? How much has your bill decreased since getting solar panels / evacuated tubes?
Also 30 tubes for 300 litre system kingspan hp400 looks good or any other recommendations? what temperature to expect in winter from solar?

Calahonda52

IMhO, Solar thermal is completely uneconomic from a financial perspective.

My principle problem with it is that the design is occupancy driven, just like your outline.

so when the tank is heated to the required temp, then what happens the excess hot water
Properly done PV is a better option, with much less maintenance issues.

Plenty on this forum about both

froshtyv

It would be more economical to meet your domestic hot water means by oil.

Half a fill of oil would suffice for normal house hold (4 people)

Lets say €350 for a half a fill of oil.

At a push for a year solar might save you €200 from this bill

So you still need to make up the other €150 by means of oil or immersion

Divide your savings into the capital cost. I will use €5,000 as an example for supply and install

5000/200 = 25 years to pay itself off.

You will also need to take into consideration maintenance costs ever 2-3 years which will only push out the payback period.

pod2011

Would it be more economical to maybe set up a low cost solar pv.
maybe a 500 watt solar panel wired to the sink element of the immersion?
I know with inverters you have losses but if on a dull day and the panel is only generating 250 watts will this still heat the element a bit?

K.Flyer

pod2011 wrote: »

Would it be more economical to maybe set up a low cost solar pv.
maybe a 500 watt solar panel wired to the sink element of the immersion?
I know with inverters you have losses but if on a dull day and the panel is only generating 250 watts will this still heat the element a bit?

No, as the element requires 2.5 - 3kw, imo a total waste of money for that idea.

pod2011

Thanks for your input, but I wrote sink element I know to power the bath element 3 kw will be expensive but the 500 watt sink element?

If you could have the top half of the cylinder hot it would be easier to heat the rest?

Sleeper12

pod2011 wrote:

Thanks for your input, but I wrote sink element I know to power the bath element 3 kw will be expensive but the 500 watt sink element?

Sink element isn't 500 watt. Sink element is usually the same as bath element. 2.5 to 3kw.
The difference between sink and bath isn't the kw. The difference is one heats half of the cylinder and one heats the full cylinder. It costs more or less the same to heat half a cylinder using bath or sink element

ptogher14

Sleeper12 wrote: »

Sink element isn't 500 watt. Sink element is usually the same as bath element. 2.5 to 3kw.
The difference between sink and bath isn't the kw. The difference is one heats half of the cylinder and one heats the full cylinder. It costs more or less the same to heat half a cylinder using bath or sink element

Sleeper 12, sink element is not the same as a bath element. It is generally shorter than a bath element and requires less power. Although it wouldn't be 500w.

Sleeper12

ptogher14 wrote:

Sleeper 12, sink element is not the same as a bath element. It is generally shorter than a bath element and requires less power. Although it wouldn't be 500w.

I know that the bath element is longer than the sink element. It couldn't heat a full tank if it wasn't.
Now it's been awhile since I replaced an element if memory serves the sink element curls back on itself. If stretched out is more or less the same length as the bath element.

Also a cylinder with side loaded elements has 2 separate elements. Both are the exact same size & KW.

dathi

pod2011 wrote: »

Would it be more economical to maybe set up a low cost solar pv.
maybe a 500 watt solar panel wired to the sink element of the immersion?
I know with inverters you have losses but if on a dull day and the panel is only generating 250 watts will this still heat the element a bit?

a small pv system would be wired into the whole house electrics to help with the houses base load usage . a larger system can be wired with a diverter which will divert excess electricity to the immersion to prevent it being exported to the national grid.

ptogher14

Sleeper12 wrote: »

I know that the bath element is longer than the sink element. It couldn't heat a full tank if it wasn't.
Now it's been awhile since I replaced an element if memory serves the sink element curls back on itself. If stretched out is more or less the same length as the bath element.

Also a cylinder with side loaded elements has 2 separate elements. Both are the exact same size & KW.

Even if they are the same length they require different power. Simple test, measure the resistance of each element. The sink will have higher resistance, so it will draw less current.

Sleeper12

ptogher14 wrote:

Even if they are the same length they require different power. Simple test, measure the resistance of each element. The sink will have higher resistance, so it will draw less current.

Cylinder with 2 side elements has identical elements. The exact same kW. Sink element has the same resistance as bath element. They both require the exact same power.

I'm really not understanding what you are saying?

K.Flyer

So here are the images of a 24" dual immersion element that I installed today.
As you can see from the images Black cable to sink is 2 kw and Brown cable to bath is 2.85 kw.

ptogher14

Do you understand now sleeper 12?

Sleeper12

ptogher14 wrote:

Do you understand now sleeper 12?

Not at all. 2 separate immersions wired into sink /bath switch & separate timer. Both immersions are the Same kW. I don't understand how the bath /sink switch can make the top immersion run at a different power rating.
I've honestly never heard of such a thing. It doesn't make sense to me.