Sun and Wind Power

zeupater

MrAndMrs wrote: »

Fair point. I'm not sure how much PV it costs these days. I only looked at the price about 3 years ago. We decided to get solar thermal as it was half the set up price compared to PV. I got a solar thermal system installed for £2.5k and we worked out it saved us around £800 a year off out gas bill. If I recall correctly, We would have got less back from PV. But like I said, things have probably improved since then.

Hi

Probably overestimating the saving a little there (x10 ?). We've got a pretty large thermal system which provides the majority of our DHW and it saves well under £100/year in gas ... the biggest saving is to allow us to move to zero standing charge supplier, almost doubling the saving, but that's about it.

There is an advantage on system footprint ... our system covers about 25% the roof area of a 4kWp pv system and provides us with around 50%(kWh.t) of what a 4kWp system does - and that's limited more by DHW requirement than capacity ...

HTH
Z

MrAndMrs

zeupater wrote: »

Hi

Probably overestimating the saving a little there (x10 ?). We've got a pretty large thermal system which provides the majority of our DHW and it saves well under £100/year in gas ... the biggest saving is to allow us to move to zero standing charge supplier, almost doubling the saving, but that's about it.

There is an advantage on system footprint ... our system covers about 25% the roof area of a 4kWp pv system and provides us with around 50%(kWh.t) of what a 4kWp system does - and that's limited more by DHW requirement than capacity ...

Just curious what was your initial set up cost? And what direction is your array facing and what angle is it set up at?

Our roof is pretty much bang on south and at a 45 degree angle which I believe is quite good. We live in a fairly well insulated house (but by no means carbon neutral).

zeupater

MrAndMrs wrote: »

Just curious what was your initial set up cost? And what direction is your array facing and what angle is it set up at?

Our roof is pretty much bang on south and at a 45 degree angle which I believe is quite good. We live in a fairly well insulated house (but by no means carbon neutral).

Hi

Set up cost is irrelevant as we may have underpaid/overpaid, used different thermal panel technologies (plate/tube), had atypical installation requirements, an oversized/undersized system or had it for a long/short time .... as for orientation, it's approx. SW, but that really makes little difference - the relative differential due to orientation and roof angle can be estimated using PVGIS, therefore simply over specifying the collector area can easily compensate. We make best use of insolation/irradiation when available by having oversized storage and feed that with oversized collectors, therefore negating the usual requirement for backup heating over a period of consecutive dull days ....

As for insulation, like you we live in a pretty well insulated house, but again, for DHW it makes little difference - it's the insulation on your cylinder (/thermal store), the DHW pipes and the solar circuit which is important ....

Carbon neutral ? ... in terms of domestic energy requirements we're there, and have been for a few years - we have a net positive balance of non-renewable energy source import (gas&electricity) to generated energy exported, with the bulk of our winter heat being provided from renewables ...

HTH
Z