Solar collectors and photovolatic this year

[sas]

The prinicipal issue with using solar collectors (for heating water, not to be confused with Solar PV) for space heating is that when you most need the heat i.e. in winter at night, there is no sun

Hi,

How much heat (towards space heating) can you realistically expect to get from solar panels in the heart of winter during the limited daylight hours we get? What sort of additional cost in terms in the thermal store etc. would you incur to try and get the benefit from it?

Given that most of us will be incurring that additional cost on the mortgage, you can effectively double whatever you pay over say a 30 year mortgage term. Does it still make financial sense?

SAS

 

[Startup]

Hi SAS
The worst winter day only provides 10% of the solar radiation in summer, so in order to heat the same quantity in winter you need a lot more panels than would normally be specified for a 'summer sized' system. The thermal store could be in the order of 1000 litres for domestic space heating. A standard 300 litre stainless steel tank is around €1500 so if you pro rata that you see how the cost starts to stack up. To be honest I haven't done the maths on this solution, but would be happy to talk with anyone who wants to seriously examine it. The best place to start with something like this is to examine the annual opertion cost of a conventional heasting system. The avergae household spends 50% of the annual energy cost on space heating, so the equation is somewhat different in terms of calculating the cost benefit. I don't quite follow your reference to mortgage repayments. can you elaborate?

 

[sas]

I don't quite follow your reference to mortgage repayments. can you elaborate?

My point was that in most cases on new builds the money is borrowed and hence subject to interest. For any mortgage amount initially borrowed you can realistically expect to repay double that over a 30 year term. So if I borrown an additional 3000 euro extra for the thermal store, its really going to cost me 6000 euro by the time I've paid for it.

 

[sas]

The best place to start with something like this is to examine the annual opertion cost of a conventional heasting system.

This needs to be taken into account but you couldn't rely on a solar only heating system without some form of back up. So you most likely would end up paying for a conventional system anyways that costs slightly less to run based on the benefit provided by the thermal store.

I take your point though, higher initial installation cost but much lower running costs.

 

[Startup]

Sorry, I'm with you now. You're right typical lifetime mortgage repayments I would have put at 1.8 x the original sum borrowed. Remember that a grant of €300 per metre squared of absorber area is payable by SEI for installations limited up to 12 metres squared of panel. This helps to dampen the fiscal blow a little. I am working on a commercial project for a customer at the moment who wants to use solar to contribute to space heating requirments, but I've already warned him that the economics may not make sense.

 

[Silvergirl]

Hi Armada,

The quotation is part of our plumbers quotation, I didn't see them on the Velux.ie price list, so I've emailed their enquiries@velux.ie for a price also,

Rgds,

 

[towbar]

Startup - is the thermal store the same as the buffer tank thats used with wood pellet boilers? It is supposed to only lose 1 degree over 24 hours (500l).

We were hoping at some point to add solar to our buffer tank as a secondary heating source. Even if it didnt heat up the tank fully it would at least reduce the amount of pellets used.

I know even during summer there will be some evenings where the house requires a top up of heat late evening so using solar for only heating water means you still have to have the boiler available. If solar heats our buffer tank during the day to at least 60 that would heat the hot water and provide for a heating top up in the house if required.

 

[Silvergirl]

Ok price back from Velux in UK re solar panels: Eur 4400 ex vat for 7.5 sqm

You can download a brochure and price list from
www.carbon-neutralhomes.ie but they are only available to buy from builders merchants etc not direct.

They are set into the roof like a regular velux roof window.

Anyone had any experience please let me know.

Thanks

 

[Startup]

Hi Towbar, I haven't looked at wood pellet systems in detail. I would need to see a specification for the buffer tank. I would doubt the heat loss statistic of 1 degree in 24 hours. This statistic seems to be thrown around by sales people in the heating industry. I can assure you that there are very few tanks on the market that would come close to or achieve this level of heat retention.
Solar could be used very effectively if sized correctly for your system for summer time contribution. Have you specifcations/schematics of the system that you've installed?

Startup - is the thermal store the same as the buffer tank thats used with wood pellet boilers? It is supposed to only lose 1 degree over 24 hours (500l).

We were hoping at some point to add solar to our buffer tank as a secondary heating source. Even if it didnt heat up the tank fully it would at least reduce the amount of pellets used.

I know even during summer there will be some evenings where the house requires a top up of heat late evening so using solar for only heating water means you still have to have the boiler available. If solar heats our buffer tank during the day to at least 60 that would heat the hot water and provide for a heating top up in the house if required.

 

[Mrs Aol]

Hi, I know this is an old thread but I did say I'd come back with info having been in house a year.

Well our year is up today! We've used 1150kg of pellets. This is to run heating for 2000sqft (I'm here all day with 2 children so it needs to be warm all day) and all hot water for 2 adults and 2 children (including hotwater feeding dishwasher and showers (obviously we don't have electric showers!)).

We have about 12sqmt flat panels.

We reckon we didn't really figure out the best settings to have until about Dec. We were wasting pellets and heat but sorted now and I expect next years total to be lower (maybe by about 2 or 300 but that just a calculated guess on my part).

We're happy with the system the only complaint was that before we completely got the hang of it we were sometimes too hot - especailly when we had visitors - everyone knows now to come in a teeshirt and flipflops all year around!