Browse Forums Eco Living Re: Gas Newbie questions 2Nov 12, 2017 11:54 pm 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Gas Newbie questions 3Nov 13, 2017 4:38 am The major energy requirements in your house are to heat your water, & space heating (depending on your climate & the quality of your build). In comparison, cooking requires very little energy use. So, 1. If you use little gas, then bottled gas is cheaper than a natural gas connection. However, if you use a lot of gas, bottled gas is much more expensive than connected gas. It sounds like you'd have very high hot water usage, so bottled gas could work out too be very expensive. 2. Some people still prefer gas cooking, while others are very happy with the switch to induction cooking. Induction is certainly far better than electric element cooking, & more efficient than both electric element & gas. 3. A standard electric element hot water system can basically be considered to be like a large insulated kettle. It's basically nearly 100% efficient (with some heat losses over the time of storage), converting each kW of electricity to a kW of heat. But electricity is expensive at peak rates, so it's an expensive way to heat water at peak times. Though much more affordable at off - peak rates. But when sourcing electricity from the grid it's not a green option, as most of the electricity would be sourced from coal generation. In this instance gas would be considered to be greener. Though this will change as the grid moves towards more renewables. But there are a couple of other options for electric hot water (plus instant electric, which I won't discuss). Firstly, heat pump hot water systems. These work much like reverse cycle air conditioning (which is actually a type of heat pump), extracting heat from the air. These are extremely efficient, with at least 300% efficiency. Some RC AC are up to 700% efficient! So heat pumps require little electricity to operate, & are cheap to run. They are however quite expensive to buy, good units anyway. While cheaper units have some major quality issues. Secondly, using electricity generated by solar PV to heat your water (with either a heat pump or electric element system). This is a very, very good idea. As the heating of hot water is a high energy use, why not heat that water for free with the electricity you've generated from the sun. The other option is heating water with solar thermal (panels or evacuated tubes). But these systems are expensive, & can only be used to heat water. Solar PV is considered to be a far better investment. I'm a little confused. You say you have no gas, electric hot water, RC AC for space heating, a solar PV system, & induction cooking. But are considering gas, for both cooking & water heating. I can only assume, with such major changes, it must be for a new build. Is that right? In any case, I'd recommend against installing gas. I'd recommend an all electric home, with a large PV system (if it's a new build designing a roof to accommodate it). With your sized household, at least a 5kW (inverter) system, oversized to over 6kW of panels, if your energy provider limits you to 5kW for single phase connections. If you have 3 phase power, you may want to even consider a larger PV system. Modern inverters, like Fronius, will send any excess power to your electric hot water system, so it's a great way to heat your water for free in the daytime. If this query is for your current home, I'd also recommend against a gas connection. However, deciding how to heat your water is more complicated. As your 3kW PV system won't produce enough power to satisfy all of your household needs, including your hot water needs. You could couple your solar PV with an efficient heat pump hot water system, however this is often considered to be expensive overkill. Or you could increase the size of your solar PV system. You have to consider the cost, plus whether you'd be losing a high FIT rate. Lastly, if you don't have excess PV generation, & increasing your PV isn't an option, you may just want to stay with your current system, with off - peak water heating. Battery systems are not yet economically viable for most people. This will certainly be the case in your situation. As you have a fairly small PV system, & high hot water needs, you could self consume all your generated power in the daytime. So no need for battery storage. If you have the roof space, a better investment would be to increase the size of your solar PV. 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