# Solar PV or Solar Thermal



## lonelyplanet (5 Feb 2020)

Hi,
 Currently renovating an old stone house and currently looking at insulation and installing Solar PV and / or Solar Thermal. Anyone got any recommendations on Solar PV and possibility of supplying back to the grid. Can anyone recommend any installers in the Mid West...Any recommendations are most welcome

Thanks
 lonelyplanet


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## Ravima (5 Feb 2020)

Can only advise from experience. I had the CAREYGLASS tubes installed. Alas, they were installed incorrectly and it took a few years to have the situation corrected. Since corrected, I'm very happy, but the shocking substandard installation was terrifying, once seen by engineer. I would suggest that whatever system you go for, you withhold a substantial payment until certified as safe by a qualified engineer. By engineer, I mean a BE or a Trinity BAI.


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## Zenith63 (5 Feb 2020)

I think the general consensus has now shifted firmly to solar PV. The electricity generated can be used for whatever is going on in your home while it is generating, excess can be stored in a battery or put into an electric car if you have one and further excess can be used to heat hot water in your tank using a diverter to the immersion heater.

You cannot currently sell electricity back to the grid, though there seems to be more and more talk of something be introduced in the next year or two, but who knows.

There are decent grants available from the SEAI to install solar PV and a battery, and they also have a list of approved installers. You absolutely need to get a few prices though, there are some companies out there (one of which appears at the top of most Google searches) that are using very pushy sales tactics with ridiculously high prices. You also need to do a bit of research to understand what size of system will suit your needs, particularly when it comes to the battery where oversizing will lengthen your payback time fairly significantly.

Just had a solar PV system + battery + diverter installed last month, as a techy and green energy enthusiast it’s one of the best gadgets miney can buy! FWIW between this and a few other small changes in the house it went from a BER C3 to B1.


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## Buddyboy (6 Feb 2020)

As Zenith63 said, if you install solar thermal, all you can do is heat water. If you install solar pv, you can heat water plus use any other use for electricity.  If you are allowed to sell excess back to the grid in the future, then in effect you have futureproofed the installation.

I was in Germany last year, and I would guess that they can sell back to the grid, judging by the amount of roofs, including barn roofs that were covered completely in solar PV panels.  I could see no solar thermal panels at all.


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## Leo (6 Feb 2020)

Zenith63 said:


> there are some companies out there (one of which appears at the top of most Google searches) that are using very pushy sales tactics with ridiculously high prices.



I think a good rule for anyone considering spending a lot of money on any product or service, if the sales people appear pushy and are offering a significant discount if you sign up today (or in a very short time), just walk away. In almost every case that discounted price will be far more expensive than the competition.


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## ALEXA (8 Feb 2020)

Zenith63, you have recently had a solar PV system installed. Can I ask you what is the orientation of your property and what approximately was the cost nett of SEAI grants etc. ?  What size of battery/ies did you need and where are they located? I'm not being nosey and understand if you don't want to answer but the reason I ask is that I'm considering the same system and would appreciate your advice and any information you can offer. Many thanks.


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## Zenith63 (8 Feb 2020)

ALEXA said:


> Zenith63, you have recently had a solar PV system installed. Can I ask you what is the orientation of your property and what approximately was the cost nett of SEAI grants etc. ?  What size of battery/ies did you need and where are they located? I'm not being nosey and understand if you don't want to answer but the reason I ask is that I'm considering the same system and would appreciate your advice and any information you can offer. Many thanks.


My South roof is a bit small, so went with 7 panels on the East and 7 on the west West for a total of 4.8kWp. 5kW hybrid inverter. 5.2kWh of batteries as well. And finally a diverter to the immersion for any excess. Total was €8k after the grant.

As I say above I’m into technology and the environment and have two electric cars, so the system is probably over spec’d compared to what the average house might need.

FWIW there’s a good thread in the Renewable Energies section of boards.ie where loss of people have posted their quotes, so you can get a sense of what you should be paying. Be warned there are some companies in the space, one in particular that often appears at the top of a Google search for solar, that are using very sharp sales tactics with crazy prices. Get three quotes, or message somebody on the boards.ie thread who is happy with their outcome.


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## ALEXA (9 Feb 2020)

Thanks for the info Zenith63. Your system sounds ideal for your needs. Like you I'm very much in favour of renewable resources and feel this is certainly a good option for me going forward. I'll definitely do as you've suggested  - get all the information and shop around before committing to anything. It would be interesting to hear from you over the next year or so letting us know how your system is performing. All the best and thanks again.


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## EricBul (14 Jun 2020)

Ravima said:


> Can only advise from experience. I had the CAREYGLASS tubes installed. Alas, they were installed incorrectly and it took a few years to have the situation corrected. Since corrected, I'm very happy, but the shocking substandard installation was terrifying, once seen by engineer. I would suggest that whatever system you go for, you withhold a substantial payment until certified as safe by a qualified engineer. By engineer, I mean a BE or a Trinity BAI.


Very interested in your experience. I had a solar thermal system installed in 2010. Carey Glass was the supplier but not the installer. Several mistakes was made during installation but they were all eventually resolved. I have had loads of hot water for the past 10 years and up until recently I have been more than satisfied. However FIVE of my evacuated tubes are now broken and Carey Glass say that they no longer supply these. Can anyone point me in the right direction? Surely there must be dozens of Carey Glass clients who are now in the same position as I am.


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## RobFer (26 Jul 2020)

PV is a lot more trendy but one thing to bear in mind that storage is the big thing. Electricity can be stored with a battery but it does add to costs while thermal is arguably free to store in your hot water cylinder. Gradually your cylinder cools and you lose that water battery but it does provide some heating. Thermal is extremely useful for big families. It will be possible to sell excess energy to the grid but the price offered is probably going to be a pittance.


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## Zenith63 (26 Jul 2020)

Ah it’s a bit more than trendiness I think. A solar thermal system will only generate hot water, and if you’re on mains gas heating water is the cheapest forms of energy you’ll be using in your home and not a big one either. Solar PV will run all your appliances, heat water, charge your car etc..

If you’re going to go to the expense of getting somebody up on the roof to install a solar system, rooting around in your attic, maintaining it and all the other cost/complexity, to me it makes much more sense to put up solar PV and offset electricity which costs significantly more than gas. A battery is entirely optional, a properly sized array will cover a significant portion of your electricity usage without one.

I haven’t seen a new solar thermal system installed in quite a number of years.


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## dragonboy (31 Oct 2020)

Hi 
We are considering solar PV  however I am new to this and have a few questions, currently there are 6 of us in the house, 4 kids soon to be teenagers so showers get loads of use. But currently we have two electric showers and a very very small water tank in hot press and small attic tank so my question is do we need to replace the two tanks and showers and some plumbing etc... if so is this not a cost effective option ? Would we be better to get a combi boiler as our boiler would need replacing soon too although not causing any problems but is 17yrs old.


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## Zenith63 (31 Oct 2020)

Generally the cost of installing the immersion diverter (which takes excess electricity generation and uses it to heat water) never pays for itself.

So don’t worry about your hot water situation, get as many PV panels as you can fit on your roof (they’re the cheap sort, so while the roofer is up there max it out!) and perhaps consider a small solar battery. This way you’ll use the solar first to power your home, then to charge the battery, then any excess is exported to the grid.The Green Party intend to introduce an export tariff so you’ll likely be paid for the export some day.

Gotta remember that while 5kW of panels sounds like a lot, you’ll only generate that for a few hours on a few days in the height of summer. The rest of the time it will be generating 1/2/3kW depending on the time of year.

Also think about when you switch to an electric car or two they will suck up any excess solar and then some!


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## Alkers86 (3 Nov 2020)

dragonboy said:


> Hi
> We are considering solar PV  however I am new to this and have a few questions, currently there are 6 of us in the house, 4 kids soon to be teenagers so showers get loads of use. But currently we have two electric showers and a very very small water tank in hot press and small attic tank so my question is do we need to replace the two tanks and showers and some plumbing etc... if so is this not a cost effective option ? Would we be better to get a combi boiler as our boiler would need replacing soon too although not causing any problems but is 17yrs old.


I would think that getting the shower situation addressed first would be more-beneficial. A unit of energy from gas is about 1/4 the price of a unit of energy from electricity and power showers are much much better than electric showers. Combi boilers are I think the best solution for small households but won't be able to supple two showers at the same time. You may have to keep one shower as an electric shower. Do you use the two showers at the same time frequently? How big is your house, depending on the number of rads, a combi-boiler may not be appropriate.

I would talk to a plumber in the first instance, solar PV is more than likely a 15 year return on investement.


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## dragonboy (3 Nov 2020)

Alkers86 said:


> I would think that getting the shower situation addressed first would be more-beneficial. A unit of energy from gas is about 1/4 the price of a unit of energy from electricity and power showers are much much better than electric showers. Combi boilers are I think the best solution for small households but won't be able to supple two showers at the same time. You may have to keep one shower as an electric shower. Do you use the two showers at the same time frequently? How big is your house, depending on the number of rads, a combi-boiler may not be appropriate.
> 
> I would talk to a plumber in the first instance, solar PV is more than likely a 15 year return on investement.


Hi 
Thanks for this advice, but replacing showers goes hand in hand with option of either going for the solar PV or combi boiler, house is a 4 bed 1,700 sq meters. No we really just use the one shower the second shower is on ground floor and rarely used. Re the solar am I correct that I would need to replace the showers and tank and attic tank , maybe not worth it? Appreciate all advice


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## Leo (4 Nov 2020)

dragonboy said:


> house is a 4 bed 1,700 sq meters.



Feet I presume?



dragonboy said:


> Re the solar am I correct that I would need to replace the showers and tank and attic tank , maybe not worth it? Appreciate all advice



If you're going solar thermal then you will need to replace the hot water cylinder, and the electric showers. The header tank in the attic can stay.


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## Zenith63 (4 Nov 2020)

dragonboy said:


> Hi
> Thanks for this advice, but replacing showers goes hand in hand with option of either going for the solar PV or combi boiler, house is a 4 bed 1,700 sq meters. No we really just use the one shower the second shower is on ground floor and rarely used. Re the solar am I correct that I would need to replace the showers and tank and attic tank , maybe not worth it? Appreciate all advice


Just checking you saw my reply a few posts back?

Solar PV is about generating electricity, not hot water.  You CAN use it to divert excess generation to your hot water tank, but the cost of doing so is usually greater than the saving you would ever make.  So your solar PV ambitions are decoupled from your showers/hot water tank plans.


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## shweeney (4 Nov 2020)

Zenith63 said:


> Just checking you saw my reply a few posts back?
> 
> Solar PV is about generating electricity, not hot water.  You CAN use it to divert excess generation to your hot water tank, but the cost of doing so is usually greater than the saving you would ever make.  So your solar PV ambitions are decoupled from your showers/hot water tank plans.



from what I've read the economics of buying a battery are also dubious as they have a limited number of discharge cycles. There's an extra grant for a battery so get one that's as close in cost to the grant as possible, buying a bigger more expensive battery may never pay back the cost.


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## Alkers86 (4 Nov 2020)

dragonboy said:


> Hi
> Thanks for this advice, but replacing showers goes hand in hand with option of either going for the solar PV or combi boiler, house is a 4 bed 1,700 sq meters. No we really just use the one shower the second shower is on ground floor and rarely used. Re the solar am I correct that I would need to replace the showers and tank and attic tank , maybe not worth it? Appreciate all advice


You need to talk to a plumber then about whether a combi boiler would suit your house or not, it might just manage if you leave the downstairs shower as an electric shower.

Solar PV doesn't really have much to do with showers, if you get a combi boiler, you will have no hot water tank to use the diverter that you're thinking of but even with a hot water tank, you'll be a long time making any money back on a diverter, particularly if a FIT comes in, you will end up losing money.

If I were you I would talk to the plumber and your two options (in my order of preference would be) replace boiler with combi boiler and leave one electric shower in place. Then you can install solar pv afterwards or beforehand- no difference. OR you get a new, much larger insulated hot water tank and upgrade one or both your showers to power showers. You might look at a new boiler also. This will give you the option of installing either solar thermal (good at heating water) or installing solar PV with a diverter.


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## dragonboy (8 Nov 2020)

Thanks for your response very helpful


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