Gas or solar electricity for heating

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Gas or solar electricity for heating

Postby Catewill » Tue Dec 06, 2011 5:31 pm

Hi

I live in Perth and am new to this forum, so I hope I'm not asking silly questions.

Last April we moved into a new house that does not have gas connected (although there is gas in the street). We got through the winter using a very cheap convection heater. Although we were overseas for 6 weeks of the winter, we had someone living in the granny flat using a small column heater so our electricity bill was very high (>$300).

We need a better heating solution in place by next winter and have two gas heaters so we could get the gas connected and use those. However, I'm leaning towards getting a solar system installed (the house already has solar hot water) and then investing in two efficient electric heaters. Summer cooling is not a problem as the house already has an evaporative air conditioning system and fans installed.

Has anyone else on the forum had the gas/solar dilema and if so what did you decide to do? And can anyone recommend an efficient electric heater.

Also, I've just started looking into solar systems and it all seems very confusing. I thought the government rebates had stopped but there still seem to be some incentives for people installing solar. Can anyone point me in the direction of a post that explains the issue simply?

Thanks
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Re: Gas or solar electricity for heating

Postby Gordon-Loomberah » Tue Dec 06, 2011 9:45 pm

Welcome to the Energy Matters forums Catewill :)

Catewill wrote:Has anyone else on the forum had the gas/solar dilema and if so what did you decide to do? And can anyone recommend an efficient electric heater.


Any electric heater with just an element and a fan is never going to be efficient, you only get 1kW of heat for 1kW (plus the energy the fan uses to move the air) consumed. Very similar to the electric HW systems that are no longer going to be sold... due to how inefficient they are. If you want efficient electric heating, it really has to be reverse cycle air conditioner/heat pump technology- there you can get over 4kW of heating for 1kW of consumption- with careful study of specs and COPs to select the right unit. Not all are that good.

To heat a house with solar hydronics, you'll need 50-100 evacuated tubes (I use 78) and 1000+ litres of water, depending of course on how big the house is, how well insulated, and how much sun you get. High initial cost, but no ongoing costs like with gas or electric heating.
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Re: Gas or solar electricity for heating

Postby DoctorI » Wed Dec 07, 2011 12:11 pm

Catewill wrote:Hi

I live in Perth and am new to this forum, so I hope I'm not asking silly questions.



In the Office I work in we have a saying:

'There is no such thing as a silly question, just someone too silly to ask it.'

So ask away.

I am not able to provide an answer but I see one very useful answer has been posted already.
1.5 kW PV and solar hot water installed Nov 2011.
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Re: Gas or solar electricity for heating

Postby Smurf1976 » Wed Dec 07, 2011 6:19 pm

From a financial perspective, it makes no sense to use electricity simply because you are generating it yourself. Rather, you should look at the opportunity cost of using it versus gas.

What is the electricity from solar worth if sold to the utility? What rate do you pay for electricity purchased from them when the sun isn't shining? And how do these rates compare to gas?

I don't know what prices you pay in WA so I can't provide further help, but that's how you should look at it if the objective is to minimise costs. You wouldn't make house bricks out of gold just because you found it lying around, now would you? No, you'd sell the gold (or keep it as an investment) and buy some ordinary bricks because that makes a lot more sense financially. Think about your heating the same way and look at the cost of using it, not whether or not you produced the power yourself.

As for what is an efficient heater, if you're using electricity then an efficient reverse cycle air-conditioner is the most common efficient way to go as it will only use a quarter (roughly) of the electricity that any other electric heater would use to produce the same heat output.

Heating costs vary a lot between states. Eg Victoria has very cheap mains gas and about 90% of people use it. But not far away in Tasmania gas is more costly and 68% of homes are heated by electricity and a further 26% by wood (mains gas 2%, LPG 2%, oil 1%, pellets 1%).

So you really do need to check your local fuel prices. That said, portable electric heaters are generally the most expensive option regardless of where you live and bottled gas (LPG) is pretty expensive too so avoid both of those if possible.
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Re: Gas or solar electricity for heating

Postby munrre » Mon Dec 12, 2011 11:25 am

I would be looking at low cost improvements to get the most from which ever source of energy you use.
Insulation, double glazing, floor coverings, heavy curtains, caulking etc.

Unless you can build a DYI solar window heater all other solar heating solutions are quite expensive and would not IMO be worthwhile in Perth.

In Adelaide our energy efficiency minded retrofits, as above, keep us comfortable for most of Winter with very occasional use of a reverse cycle AC.

Gas heaters require adequate ventilation which means letting out the heat!
Another consideration when installing gas is any ongoing cost such as the dreaded "supply charges"
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Re: Gas or solar electricity for heating

Postby 470rigby » Tue Dec 13, 2011 9:25 am

munrre wrote:Gas heaters require adequate ventilation which means letting out the heat!


Fully flued gas heaters such as Rinnai's Energysaver line do not discharge combustion products into the room, and accordingly the room does not need to be vented.
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Re: Gas or solar electricity for heating

Postby ads » Tue Dec 13, 2011 10:47 am

Re. solar rebates the federal rebates, in the form of RECs, are still available and will reduce your install costs by approx $4,000. I would recommend getting in early as these rebates have a history of being slashed or removed with no/little notice and won't last long when the carbon tax comes in. Feed in tariffs are no longer available in WA unfortunately so you'll be screwed by Synergy who now pay 7c/kW to people who feed energy in (that's a third of what they charge!).

I think you should look into heating as a separate issue to solar generation. Gas is cheaper than electricity and I think you should look at it as a long term issue if you're going to stay there a while (ie don't be scared off by install costs if it will save you in the long run). I don't know anything about reverse cycle as i am anti aircon in general.

It goes without saying that you should definitely improve insulation, install external shading on east and west facing windows, curtains and pelmets, cross ventilation, etc to improve your's home's efficiency. Check our blog for more on this. http://sustainaburb.blogspot.com/2011/0 ... -west.html

Good luck with it, Ads
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Re: Gas or solar electricity for heating

Postby Smurf1976 » Wed Dec 14, 2011 8:05 pm

ads wrote:I don't know anything about reverse cycle as i am anti aircon in general.

It's a strange thing the air-conditioning debate.

Here in Tassie where they are used primarily for heating, installing an air-conditioner would surely be the number 1 priority for saving energy. Just that one appliance is going to save 8,000 or so kWh per annum - far more than you'll ever save with solar HWS or the average PV system on the roof. Many Tasmanians find it somewhat strange that there isn't a government rebate to encourage reverse cycle A/C installation for this reason - it's the biggest energy saver there is in a cool climate.

But then you go to somewhere with a warm climate and realise that installing A/C actually makes the power bill go up rather than down... :D
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Re: Gas or solar electricity for heating

Postby Gordon-Loomberah » Wed Dec 14, 2011 9:07 pm

I'm sure it makes the power bill go up in Tassie too!

It's a matter of comfort- you really can save power by not running the air conditioner-you can always put more clothes on/move around a bit to stay warm, but there is a limit to how much you can take off in a hot climate- at least in public :lol:
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