Maximising Solar Panel Efficiency in Winter

GoneShootin

Was speaking with someone today regarding solar panels and it was suggested to me that to maximise the efficiency of the solar system - particularly during Winter - is to use a dedicated cylinder for the solar system, which will in turn feed into the main cylinder. I'm hoping to go with a solar/oil/stove+back boiler system.

Anyone have comments on pro's - con's of this?

Evergreen

The best way to maximise heat in the Winter is to add more panels and increase the angle that the panels are sitting at. With a steeper angle the panels can get more heat from the Sun when it is lower in the sky during winter and less heat (less than having them at 35-45°) when the Sun is high in the sky during the Summer.

In Austria most households install 10 square meters these days and all the heat is fed into a buffer tank. From the buffer tank the stored heat can be used for heating the radiators as well as hot water, however, you will still need some back up in the winter regardless.

Carlow52

GoneShootin wrote: »

Was speaking with someone today regarding solar panels and it was suggested to me that to maximise the efficiency of the solar system - particularly during Winter - is to use a dedicated cylinder for the solar system, which will in turn feed into the main cylinder. I'm hoping to go with a solar/oil/stove+back boiler system.

Anyone have comments on pro's - con's of this?

re a solar/oil/stove+back boiler system
plumbing 2 or more heating systems in // can be difficult to get right as the stove one needs to be an open system and able to dissipate heat from stove during a power cut

quentingargan

Your best way of maximising efficiency in the winter is to use vaccum flasks or vacuum tubes. The heat loss off the glass in flatplates is way higher in winter time.

Austria uses 10 sq m into a buffer tank, but they have approximately double the winter daylight energy that we have. In Ireland, the contribution to space heating from solar is negligible unless you have a very poorly insulated house.

To some extent, the insulation level of your house is an important factor. During winter when the central heating is on, your hot water comes fairly cheaply from whatever system you have. In the summer, your hot water is somewhat more expensive because it either comes from an immersion, or from a boiler which is only operating to heat the water - usually not very efficiently.

For maximum winter effect though, insulation is the key, and vacuum tubes or flasks are the only really effectively insulated panels. Q

Widget

I know next to nothing about solar panels - but we are starting the plans for a 3 bedroom cottage style house in West Mayo which will be empty much of the time so having enough solar panels to provide some degree of background heat sound to me like a good idea. Would 10m2 do the job? Would that take up all of of the roof. We will have the highest degree of insulation we can afford and an energy efficent oil boiler with rads. Any advice??

Carlow52

Widget wrote: »

I know next to nothing about solar panels - but we are starting the plans for a 3 bedroom cottage style house in West Mayo which will be empty much of the time so having enough solar panels to provide some degree of background heat sound to me like a good idea. Would 10m2 do the job? Would that take up all of of the roof. We will have the highest degree of insulation we can afford and an energy efficent oil boiler with rads. Any advice??

For the project you describe I would not bother with the solar panels for a number of reasons.

1: I don't think the cost benefit is there and I would spend the money on enhanced insulation/ airtightness and perhaps a MHRV unit. - included in that is optimal orientation of the house and attention to glazing.

2: there is increasing anecdotal evidence that external oil fired boilers and more recently solar panels are being stolen from 'holiday homes'

GoneShootin

Carlow52 wrote: »

For the project you describe I would not bother with the solar panels for a number of reasons.

1: I don't think the cost benefit is there and I would spend the money on enhanced insulation/ airtightness and perhaps a MHRV unit. - included in that is optimal orientation of the house and attention to glazing.

2: there is increasing anecdotal evidence that external oil fired boilers and more recently solar panels are being stolen from 'holiday homes'

That's fine except for the fact that for a new build you need to have some form of renewable energy in place. To my mind solar gives the "easiest" solution.

Carlow52

GoneShootin wrote: »

That's fine except for the fact that for a new build you need to have some form of renewable energy in place. To my mind solar gives the "easiest" solution.

GS: No issue with the observation, just wonder would wood pellet stove work either.

If u are au fait with the general options for meeting the RE requirements perhaps you could post a link here for the benefit of the wider audience as well as the OP.
Thanks.

quentingargan

Part L of the building code is here http://www.environ.ie/en/PublicationsDocuments/FileDownLoad,15343,en.pdf

Section 2.2 stipulates that new dwellings must have 10kwhr of renewable energy production per year per sq m of floor space. If you are using electricity generation to meet this, it can be 4kw hr per year.

I may be missing a point here - is there somewhere that this is a holiday home? (ref them getting stolen - maybe that is the case here?). With a holiday home I would consider solar PVs to meet this obligation as they can export electricity even while you are away. Solar water heaters can be a nuisance as they may generate unwanted heat in a holiday home. Q

sinnerboy

Carlow52 wrote: »

the general options for meeting the RE requirements .

http://www.boards.ie/vbulletin/showthread.php?t=2055500071

quentingargan

Widget wrote: »

I know next to nothing about solar panels - but we are starting the plans for a 3 bedroom cottage style house in West Mayo which will be empty much of the time so having enough solar panels to provide some degree of background heat sound to me like a good idea. Would 10m2 do the job? Would that take up all of of the roof. We will have the highest degree of insulation we can afford and an energy efficent oil boiler with rads. Any advice??

Oops - my browser didn't show this post before I put in my last post. The idea that solar panels heat a house is, to my mind, false in Ireland. The concept has been mistakenly imported from Austria where an average day in December and January has more than twice as much solar insolation as Ireland. Cold bright days comparing to our wet grey ones!

Solar panels for space heating will produce unwanted heat all through the summer, but no useful heat during the damp days of winter. SEI grant aided solar space heating which was a terrible mistake to my mind.

If it is a holiday home, as per my last post, by all means have solar water heating, but just a modest panel and a large cylinder with a heat dump - it will give you free water when you are visiting. But you may like to consider meeting the Part L obligations with solar PVs or a wind turbine which can export electricity while you aren't around. It is the only case where I would consider solar PVs cost effective in meeting Part L at the moment (but prices are falling, so watch this space!)

Q

Carlow52

GoneShootin wrote: »

Was speaking with someone today regarding solar panels and it was suggested to me that to maximise the efficiency of the solar system - particularly during Winter - is to use a dedicated cylinder for the solar system, which will in turn feed into the main cylinder. I'm hoping to go with a solar/oil/stove+back boiler system.

Anyone have comments on pro's - con's of this?

GS: I would shy away from the back boiler item. Apart from the open system plumbing issues, u have to use the heat produced so in my view u may be heating rooms to a higher temp than required just to dissipate the heat.
The other issue is that the typical spiit is 1/3 room 2/3rds back boiler so if u need say 6 kw for the room the unit will be 18kw.

I put in my first bboiler 35 years ago so I think i am not 100% unqualified to comment thereon:)

PeteHeat

Hi,

I would not recomend installing 10 sqm of solar in the hope heating a house in Ireland, the two problems I see are ;

A) An oversized system during summer when sanitary hot water is the only requirement.

A system that may be undersized for winter requirements due to short day light hours, persistant heavy cloud and heating systems that very often call for high temperatures, (radiators).

If the solar system is sized to take account of our often inclement summer weather using a heat dump to cater for our very sunny days it is possible to get a side benefit in winter that many may not notice.

The solar system capable of providing a full cylinder at temperatures up to 65 > 70c in summer can pre-heat the bottom half of the cylinder anywhere from 30 > 45c in winter.

Considering the average attic storage tank will be providing the cylinder with water at between 10 > 15c in winter, there are considerable "hidden" savings made from having the cylinder pre-heated for the primary heat source to top up.

I fully agree with Carlow52 regarding the use of what are often over sized solid fuel stoves as a secondary heat source, they can be the cause of a lot of wasted fuel.

I believe there is no one size fits all answer when it comes choosing heat sources, there are questions to asked and answered such as ;

The number of occupants today and numbers foreseen in the immediate future.

Lifestyle is possibly one of the biggest issues, a young couple both working may leave the home at 6.30 AM to return at 7 PM, obviously do not require the same amount of hot water or heat levels during the day as the family of four children with one parent working in the home.

There are some projects where options should be left to allow for the changes in peoples lifestyles and of course future fuel costs.

.