Solar Panel Newbie

dfbemt

Had some evac tubes installed in Feb and was happy with what we got during the sunny weather at end of March / start of April.

I waited anxiously for the Summer months to see just how good these were. We did not use the gas at all during the summer and carried on showering, with the odd bath, as normal. All water came from the solar system.

Our gas bill came today and I was chuffed that it was only €11 for 2 months, comprising of standing charge + VAT.

I'm happy that we got the system installed and would have no hesitation recommending this to others. I do not have the technical knowledge on these systems but can say that they do work and there is a certain 'feel good' factor about the whole thing.

homer911

Check your meter reading. I got a gas bill yesterday too and the current reading is flagged with an "E" for estimated!

dfbemt

Not an E in sight, both actual readings.

John32c

Hi there,

Good news about your Solar panels...A few questions if you dont mind,
1.How much did your system cost?
2.Did you get a SEI grant..
3.How does it perform in cloudy weather?
4.What type of shower do you have?

quentingargan

homer911 wrote: »

Check your meter reading. I got a gas bill yesterday too and the current reading is flagged with an "E" for estimated!

Eh, if it was estimated, it would have been based on last years bill, which would presumably be a lot more.

Well done. In my experience, vacuum tube or flask system work remarkably well, even in mediocre weather. Its quite surprising!:)

homer911

Ah yes! but I had my panels last year too...

dfbemt

John32c wrote: »

Hi there,

Good news about your Solar panels...A few questions if you dont mind,
1.How much did your system cost?
2.Did you get a SEI grant..
3.How does it perform in cloudy weather?
4.What type of shower do you have?

System I got was tube based, mounted on roof of 5 year old house, SSE aspect

1. Cost €4,900 for all, reduced from €6,500 last July !!
2. Grant was €900 (to be deducted from €4,900 so total I paid was €4,000)
3. Performs quite well. Plenty of cloudy days this summer (!!) and no need for gas boiler on. Solar provided all dhw
4. 3 power showers with 3 kids in house

Happy to answer other questions, prob best to do through pm. Very happy with company who provided and installed

BraziliaNZ

hi what company did you use for this?

dfbemt

PM sent with supplier details to Brazilia

derry

dfbemt wrote: »

System I got was tube based, mounted on roof of 5 year old house, SSE aspect

1. Cost €4,900 for all, reduced from €6,500 last July !!
2. Grant was €900 (to be deducted from €4,900 so total I paid was €4,000)
3. Performs quite well. Plenty of cloudy days this summer (!!) and no need for gas boiler on. Solar provided all dhw
4. 3 power showers with 3 kids in house

Happy to answer other questions, prob best to do through pm. Very happy with company who provided and installed

Sounds like that if prices of fuel remain steady it will take 20 years to pay back the initial cost

Derry

robtri

derry wrote: »

Sounds like that if prices of fuel remain steady it will take 20 years to pay back the initial cost

Derry

and how did you figure that out??? you have no idea of his hot water usage...

Flossy Flossy

dfbemt how much did you save on your bill ?

dfbemt

Bill for Jun / Jul was €45 down on last summer.

Bill for Apr / May was €52 down on last year.

So nearly a €100 saving on 2 bills to date.

After a year i will look at if we could save more by dropping the standing charge and going for a higher rate per unit of gas used.

Other than that, and TBH, there is a feel good factor knowing that the sun is heating the water and our gas is off. A previous poster said it would take 20 years to pay back the cost. It won't, but so what if it did. I am happy, my kids have learnt something from it and I will save more if gas prices go up. Plus, if I ever sell, my BER rating has improved !!

I thought about it for approx 12 months, had different quotes and different systems recommended. In the end I just went for it and am glad, for a number of reasons and not just monetary, that I did.

My advice, if you are interested and have the money to spare, go for it.

dfbemt

I thought I would follow up on my earlier posts.

Next gas bill received today and this bill was only €13. €2 more than previous but we had turned on the gas for an hour in the evenings for the last 2 weeks, give or take.

I was even happier about this bill as it was not only for the 'Summer' months and proved to me that the tubes are efficient even on cloudy days. I did notice on Monday this week (very dark, dull and wet day) that the temp was only in high 20's whereas during the summer we consistently had 60's, 70's.

Again, very happy with solar system and would gladly recommend to all.

00jes

I was talking to a solar company a few weeks ago that has tuv certification on there solar panel. Can any one shead any light on what tuv certification is?

Is there a reason why i havent seen it anywhere before?

Any idea's?

quentingargan

00jes wrote: »

Can any one shead any light on what tuv certification is?

TUV is one of many certifying authorities who can examine a solar panel and ensure that it conforms to EN12956. The EN cert will also provide valuable data on the performance of the panel, but you do have to have some knowledge of how panels work to understand the performance aspects.

Many manufacturers use Fraunhofer, SPF or other test centres. They all perform similar tests. TUV has a reputation as it works in many other areas as well as solar.

However, the only company I know who make a big song and dance about their TUV certification being something special, have been using what appears to be a fraudulent cert. I won't name names here, (unless moderator thinks I should) but I have emails from TUV to the effect that they have been consulting their legal team about an Irish solar supplier. PM me with the name of supplier and I will say yea or nay if that's them. Q

Khannie

Is 4K an average amount for the solar panel installation? We were talking about it recently, but time until the system has paid for itself is a consideration for us. We have an electric shower which we use quite a bit but other than that we don't use a huge amount of hot water (except in the heating system of course).

quentingargan

Khannie wrote: »

Is 4K an average amount for the solar panel installation? We were talking about it recently, but time until the system has paid for itself is a consideration for us. We have an electric shower which we use quite a bit but other than that we don't use a huge amount of hot water (except in the heating system of course).

There are good systems being retrofitted for €4,500 which, after the grant, work out at €3,500.

But it doesn't look like you use much hot water, unless you wanted to replace the electric shower with one that runs off the hot water. The viability of that depends on the number of people in a house.

It also depends a bit on how well insulated your house is and often the central heating system is on. If your heating is on for 6 months or more, it heats the water quite cheaply. However, when the heating is off, and you are relying on an immersion, that's when the solar panel really saves you money.

I've come across one company doing a €4,000 system, but instead of changing your cylinder, they relied on a heat exchanger outside the cylinder and there are inefficiencies with this system that have been discussed elsewhere on this board. (page 2 of this one)

However, if you already have a very good and well insulated cylinder, there is a new retrofit coil which goes inside the cylinder that might enable you to install a modest system at a very low price (probably below €3K).

strawberryzoe

Hello all, sorry for tagging along to this thread but I have a query about the three power showers used with your solar water feed. Do you have a gas boiler so if the water isn't hot enough this would just heat up using the gas to provide the hot water for your shower?

The reason I ask is that I’m looking to install a solar panel whilst renovating my house however am concerned about how to heat the water for the showers. I had planned to install electric showers but there wouldn’t be much point in my mind of having the solar panel if I don’t use the hot water. The existing shower is heated via the electric immersion and solid fuel burner (only in the winter!) and we have no gas or oil at the property. I’m not keen on the idea of heating the immersion with electricity to run the shower as I would have thought an electric shower would be more efficient in heating the water directly.

Any ideas welcomed?

quentingargan

strawberryzoe wrote: »

Hello all, sorry for tagging along to this thread but I have a query about the three power showers used with your solar water feed. Do you have a gas boiler so if the water isn't hot enough this would just heat up using the gas to provide the hot water for your shower?

The reason I ask is that I’m looking to install a solar panel whilst renovating my house however am concerned about how to heat the water for the showers. I had planned to install electric showers but there wouldn’t be much point in my mind of having the solar panel if I don’t use the hot water. The existing shower is heated via the electric immersion and solid fuel burner (only in the winter!) and we have no gas or oil at the property. I’m not keen on the idea of heating the immersion with electricity to run the shower as I would have thought an electric shower would be more efficient in heating the water directly.

There should always be a second way of heating the water in the cylinder, and this can be gas/oil if you have gas or oil fired heating in place already. You would normally use a triple coil cylinder in that case - one coil each for solar, solid fuel, and gas.

You are partially right in that using an immersion to heat your cylinder is less efficient than using electric showers. However, if you don't have gas fired heating that will only happen on the odd occasion when the solar panel hasn't worked, and you don't have the solid fuel in use. I assume that for the most part you either have one or the other.

Also, with a cylinder in place, you may like to use the immersion heater off-peak at night rate electricity on the occasions when you are not lighting the stove.

Q

strawberryzoe

Thanks Q for your response.

We will have an electric immersion fitted so that water can be heated if the temperature is too low however, like you say, we would hope that this would only be occasional and I would be happy to run it like that.

One concern however is that the solar panel would be facing south-east which would be result in water heating earlier in the day and we tend to shower in the mornings so I'm a bit concerned the temperature will have dropped by then, but it should still be warmer than a cold mains feed which is still beneficial!

Just have to figure out a shower system that can take a variable temperature feed, heat when it's too cold and limit the temperature when it's too hot, all whilst maintaining a decent pressure!!

quentingargan

Hi Strawberryzone. A good quality cylinder as used on solar water heating systems won't lose significant amounts of heat, provided that everything on it is properly insulated. This often isn't done properly, but by that I mean that

1) The venting pipe should go horizontal for 50cm befroe going up. That stops heat escaping up that pipe and into the loft

2) All tank fittings should be over-insulated. I usually get a length of 2" Armaflex, and put this over the other insulation, over the tank fitting and butted up tight against the tank.

3) Ensure that all central heating tappings from the cylinder are insulated until they head downhill or stop being warm.

If you don't do all that, then your cylinder will be steadily losing about 180 watts to 300 watts.

A well insulated cylinder should only drop by 2 degrees or so overnight.

Any shower mixer will take water at any temperature (as long as it is hotter than you want) and send mixed water into the shower head at the right temperature. You normally put a second mixer valve on the cylinder to prevent scalding on the domestic hot water end.

All the best, Quentin.

championc

Hi all,

Has anyone on here got a Flat Panel Collector installed ? I am just wondering as to how they compare to the Evacuated Tubes. I am considering a self install and hense I'm leaning more towards the Flat Panel.

I have the complication of having a Vaillant Combi Boiler. It's Fully Modulating which is good news but will only accept a max input temp of 25 deg C so i'll need a diverter valve for the DHW. I would also hope to use the solar heated water to assist with the heating of the water in the Central Heating circuit.

BTW dfbemt, do you use Gas for cooking or just heating at the moment ?


Cormac

quentingargan

I have vacuum flasks myself, but I've workd with flatplates and both systems work well, though the flatplates tend to do better in summer, while the tubes do better in Spring and Autumn. I would forget about any sort of major contribution to your heating though - on days when your house needs heat, the panels won't have a lot of spare energy. If your house needs heating on sunny days, your money would be better spent on insulation.

In relation to the combi boiler, you will of course need a storage cylinder. One trick in your situation is to use a thermostatic mixing valve or "blending valve / anti-scald valve". You fit it onto the hot water outlet at the top of the cylinder, but the wrong way around - put the hot water from the cylinder into the cold feed. Take the hot feed from the combi. If the cylinder is hot enough, the valve won't call for any hot water from the combi. I haven't done it myself, but have heard of it being done.

You may still need a second valve in the circuit as an anti-scald valve for safety. If your system is open vented (fed by an attic tank) you will need to use large size valves as there is some loss of pressure. It might be worth a try and is probably cheaper and easier to do than motorised valves. It will also preferentially use your solar store instead of your combi, whereas the motorised valve system tends to leave the solar water unused. Q

championc

Hi Quentin,

Many thanks for your detailed reply. My system is completely closed so there's no attic tank. While I would naturally prefer to go the Tubes route, I felt that, for a self install, the Flat Plate would be simpler just having to link up a connection to a flow and return - job done.

I assume that any pre-heating of water in the Central Heating circuit would be an advantage and so, I was considering running the return through a coil on the solar store. I know I could fit a motorized valve linked to a sensor on the Solar Store which would stop water going through it if the solar store was cold.

As a matter of interest (this may sound stupid or basic but ..), if a store fills completely, what happens when you obviously cannot take any more - you can't obviously just shut the solar down ?

My back of my house is Directly South facing (in Sth Dublin). I have no obstructions in line and have a conservatory so I know just how much heat I have with winter sun. It's roasting this morning despite the fact that there's a small bit of haze in the sky.


Cormac

quentingargan

In terms of the plumbing circuit, flatplates and tubes are quite similar. They both need a pumpstation, temperature sensors etc. I'm not an evangelist for tubes by the way - both tubes and flatplates have their merits. If you are accustomed to putting in Velux windows, you should manage a flatplate OK. I'm not a great fan of the flatplates that sit on top of the slates because I don't think their wind loading is appropriate in all Irish conditions.

But you raise an interesting question about what happens when the cylinder is hot enough. In 99% of installations in Ireland, the pump switches off, and the system goes into "stagnation". The panel heats up to between 160 and 220 degrees centigrade, all the fluid in it boils and gets pushed into the expansion vessel and the system sits there as a steam system until nightfall. Thats fine occasionally if there is a power cut, but if systems are constantly allowed to do this, the anti-freeze will degrade, compression fittings will ultimately fail, the pipe insulation in close proximity to the panel will start to degrade rapidly, and rubber on the glazing of the panel will age earlier than it would otherwise do, shortening the life of the panel.

I like to see heat dumps installed to dump this surplus heat - either using a motorised valve and dedicated radiator on the solar circuit, or using the top coil of the cylinder to dump the heat from the cylinder into the central heating system.

This is similar to what you are describing. You already have the central heating system plumbed to a coil on the solar store, usually at the top of the cylinder, so this can extract heat as long as there aren't other zone valves preventing this heat being usefully disposed of.

Because your store is unvented, you have to have at least three independent ways of ensuring that this cylinder can never boil, so be very careful that you don't plumb a system now that a subsequent plumber would not understand. Another plumber might later come in and install zone systems. You must have a bomb-proof way of ensuring that the solar panel doesn't continue heating up the cylinder, even though the dump has failed. Most controllers incorporate a second cut out temperature which is higher than the "heat dump function" temperature.

Usually this surplus heat will come at a time of the year when a well built house won't really need any heat. But a radiator in the bathroom might benefit from a bit of heat to clear the condensation, even in the summer.

Q

championc

Alot of food for thought and will hopefully feed many other members or visitors to Boards.ie.

The one bit, as you can see, that niggles me is the fact of producing more warm / hot water than I can use. Therefore, I'm starting to look seriously at Solar PV panels from the point of view that every single volt generated will pay it's way back into the grid (by winding back the meter). There is naturally merit for installation of BOTH but Solar PV's could offset the cost of heating water anyway.

With this in mind, is there any studies / charts / documents which gives the average output of a 1kw Solar PV array installed in Dublin. I want to do an aprox calculation as to the potential numbers of units generated and therefore the possible payback timespan.


Cormac

quentingargan

championc wrote: »

...is there any studies / charts / documents which gives the average output of a 1kw Solar PV array installed in Dublin. I want to do an aprox calculation as to the potential numbers of units generated and therefore the possible payback timespan.
Cormac

Depending which part of the country you are in, a 1kw array will give you between 800 and 1,000 KwHrs per year. Assuming the upper end of this and that you use half of this yourself and export the other half, your average price would be 17.5c per KwHr, and that gives you €175 per year income.

Solar PVs are coming down in price, but even if the modules fall to the much anticipated US$1 per watt (ex factory of course..), the inverters and installation will probably hold prices above about €3 per watt installed. Currently I've seen quotes of €5 to €7 per watt installed.

I've worked on projects in Spain where we were getting a feed in tariff of over 45c per KwHr exported - in SPAIN, where the sun shines lots. When the government dropped that tariff to 31c, the market for PVs bombed. It has a way to go before it is viable in Ireland.

The one exception I see is holiday homes where someone wants to meet part L compliance. Solar hot water can be more of a liability in holiday homes. Of course there aren't a lot of them being built these days..:P

championc

So it sounds like the only way that Solar PV's will be economical is if I bought the bits and pieces on eBay ??

Have you ever come across failing Vacuum Tubes - it was one of the reasons i went back looking at Flat Panel rather than Tubes ? However, something tells me from your last reply that Flat Panels weigh a tonne.

What would you reckon the payback time would be on a 2m sq Tube System in an average family home - 2A & 3K ?


Cormac

quentingargan

championc wrote: »

So it sounds like the only way that Solar PV's will be economical is if I bought the bits and pieces on eBay ??

Have you ever come across failing Vacuum Tubes - it was one of the reasons i went back looking at Flat Panel rather than Tubes ? However, something tells me from your last reply that Flat Panels weigh a tonne.

What would you reckon the payback time would be on a 2m sq Tube System in an average family home - 2A & 3K ?


Cormac

Even buying the modules ex-Shanghai, I can't make PVs stack financially on a feed in tariff of 19c. But they are a nice technology, silent, trouble-free. They have a future, but not at current prices.

There are two types of vacuum system
1) a single tube in which the copper heatpipe is welded to the glass, and
2) a twin-walled vacuum flask which is like a thermos flask with all-glass and no copper-to-glass welds.

I prefer the latter because they are a lot cheaper to replace (mass produced in China for about €5 each), and so far I haven't seen any of them fail, except in the back of a plumber's van on a bumpy road.

I have seen failure in the single layer system, and I suspect that relying on a weld between two materials with different coefficients of expansion is where the problem lies. They are also a lot more expensive to replace when they do fail.

2 SqM would be a very small system for five people in a house. There are systems with 40 tubes, 210L cylinder installed all in for €4,500, and you get over €1,000 back on the grant. It is always impossible to estimate true payback, as it depends how efficiently you have been heating your water in the summer, and there are savings from having a better quality cylinder which is usually included in a solar install. I would think that at current energy prices though, a system like that should be saving €300 or more per year.

Some folks in this industry talk a lot of rubbish about 3 to 5 year paybacks. That is nonsense. A 10 to 12 year payback is 8% to 10% return on investment - a lot more than you get at the bank, and you have the satisfaction of getting your hot water from the light instead of the dark. Also, as energy costs rise (and they will...) your payback time decreases;)