Browse Forums Building A New House 1 Apr 28, 2020 12:03 am Hi All, New member here and venturing into our 1st time build. Loving this site and been on a steep learning curve. Hoping to get some help on an upcoming decision. We have a choice between either (can't afford both): A) 340L solar HWS + 2.36kW PV with 2kW inverter. B) 5.94kW PV with 5kW inverter. Background: Perth, young family of 4, ~90sqm north roof face with no shade. Option A: Will replace the standard 26L instant gas HWS. Feel PV's are under-powered but could be added to later. Not 100% confident in solar HWS - a good, reliable hot shower is a must. Option B: Feel this is a healthy amount of kWs. Wife at home during weekdays so expect to have reasonably electricity consumption during the office hours. Leaning towards option A as think it will be easier to add solar panels in the future than to add a solar HWS. Would appreciate any thoughts on this. Cheers Re: Which Solar Package to Choose? 2Apr 28, 2020 8:53 am DreadedDr Leaning towards option A as think it will be easier to add solar panels in the future than to add a solar HWS. Unless you have bigger size inverter, there is no future proofing. You have to replace the inverter in case you have to install a reasonable solar panels. Current State: Slab/Frame/Bricklayer/Lockup/Lining/Stairs/Kitchen/Wet flooring/Painted/PCI/Got the Keys My Thread: Building Windsor 40 with Eden Brae (Caddens) Re: Which Solar Package to Choose? 3Apr 28, 2020 9:44 am We built about 2 years ago and had a similar dilemna. We thought about putting solar hot water system in and decided that for the $3000 the builder wanted to charge, it would be better to add solar panels after the build which we did 6 months later. We live in Brisbane and have 44 solar panels and 10kw inverter. That may seem like overkill which I told hubby at the time, but it has actually worked out really well. We have 4 adults living in the house. With the feed in cost to the grid and the fact we have ducted air con, we haven't paid a single power bill since it has been installed. We have actually received $1200 credit over the last 12 months. We have an electric hot water system which has a timer on it so it only heats between 7am - 4pm when the sun is usually out. And yes, we still have hot water in the morning. In comparison, the 6 months prior to having the solar installed, we paid around $1000 for our electricity, so if you use those numbers, we have actually saved on paying electricity bills for the 12 months of $2000 + $1200 credit which equals $3200 in savings for 12 months. Last year, it rained for nearly the whole month of June and we still got a credit of $20. I am not sure what sort of solar feed-in tariffs you get in Perth, but it certainly works for us. Re: Which Solar Package to Choose? 4Apr 28, 2020 12:16 pm InvincibleInDN DreadedDr Leaning towards option A as think it will be easier to add solar panels in the future than to add a solar HWS. Unless you have bigger size inverter, there is no future proofing. You have to replace the inverter in case you have to install a reasonable solar panels. Thanks for your comment. Completely expect to have to upgrade inverter in-line with the additional panels. So perhaps it is better for us to just purchase a larger inverter now rather than throwing the 2kW away when we do upgrade. Re: Which Solar Package to Choose? 5Apr 28, 2020 1:56 pm bestspecials We built about 2 years ago and had a similar dilemna. We thought about putting solar hot water system in and decided that for the $3000 the builder wanted to charge, it would be better to add solar panels after the build which we did 6 months later. We live in Brisbane and have 44 solar panels and 10kw inverter. That may seem like overkill which I told hubby at the time, but it has actually worked out really well. We have 4 adults living in the house. With the feed in cost to the grid and the fact we have ducted air con, we haven't paid a single power bill since it has been installed. We have actually received $1200 credit over the last 12 months. We have an electric hot water system which has a timer on it so it only heats between 7am - 4pm when the sun is usually out. And yes, we still have hot water in the morning. In comparison, the 6 months prior to having the solar installed, we paid around $1000 for our electricity, so if you use those numbers, we have actually saved on paying electricity bills for the 12 months of $2000 + $1200 credit which equals $3200 in savings for 12 months. Last year, it rained for nearly the whole month of June and we still got a credit of $20. I am not sure what sort of solar feed-in tariffs you get in Perth, but it certainly works for us. Very interesting and a great financial result! Perth rebate is 7c/kW-h which is at the lower end of what you have on offer in QLD. Even if we didn't get to the point of receiving credit, I would happily accept a substantially lower power bill. Will talk to builder about what it costs to 1) have electric water heater instead of the 26L instant gas and 2) increase solar kW. Cheers Re: Which Solar Package to Choose? 6Apr 29, 2020 8:22 am DreadedDr bestspecials We built about 2 years ago and had a similar dilemna. We thought about putting solar hot water system in and decided that for the $3000 the builder wanted to charge, it would be better to add solar panels after the build which we did 6 months later. We live in Brisbane and have 44 solar panels and 10kw inverter. That may seem like overkill which I told hubby at the time, but it has actually worked out really well. We have 4 adults living in the house. With the feed in cost to the grid and the fact we have ducted air con, we haven't paid a single power bill since it has been installed. We have actually received $1200 credit over the last 12 months. We have an electric hot water system which has a timer on it so it only heats between 7am - 4pm when the sun is usually out. And yes, we still have hot water in the morning. In comparison, the 6 months prior to having the solar installed, we paid around $1000 for our electricity, so if you use those numbers, we have actually saved on paying electricity bills for the 12 months of $2000 + $1200 credit which equals $3200 in savings for 12 months. Last year, it rained for nearly the whole month of June and we still got a credit of $20. I am not sure what sort of solar feed-in tariffs you get in Perth, but it certainly works for us. Very interesting and a great financial result! Perth rebate is 7c/kW-h which is at the lower end of what you have on offer in QLD. Even if we didn't get to the point of receiving credit, I would happily accept a substantially lower power bill. Will talk to builder about what it costs to 1) have electric water heater instead of the 26L instant gas and 2) increase solar kW. Cheers The feed in rate for us is 20c/kw, so that would make a big difference. Re: Which Solar Package to Choose? 7May 02, 2020 9:46 am I'm probably going to throw a spanner in the works, but I'd go for neither option. OPTION C: Larger solar PV post-build, some type of electric hot water. I wouldn't be getting solar hot water in Perth, or getting my solar PV installed by the builder. Here's why. Most things I've read say it's a much better idea to get solar SV installed after the build. This is because the builder will just sub out the solar installation, & you have no control over who installs the system. Most likely the builder subs out the work to the lowest cost quote, not the best quality system (& install). Ranked, order of importance, it's; 1. Quality of installer. 2. Quality of the inverter. 3. Quality of the panels. 4. Mounting & other components. It's very important to choose a good quality local installer. Who is well reviewed, & has a moderately long business record. You don't want a poorly installed system, that is more likely to fail. You certainly don't want warranty issues, only to find the business has closed down (often phoenixing, & starting up as another business). How does troubleshooting & warranties for solar PV work with the builder? Do you chase up the builder, or have contact details for the installer? Looking at problems people have remedying issues with their build once they've moved in, I'd hate to be chasing a builder for a solar PV system that has stopped working a few years down the track. As for the gear. You haven't mentioned the brand of inverter or panels. Have you been given this information? Or are they going to plonk any cheap Chinese gear on your roof? So I'd be installing the solar PV system post-build (maybe getting the builder to install conduit for the system, you'd have to discuss this with your chosen installer & builder). Choose a local company, that has been doing good quality installs for many years. It's pretty easy to find out this info, looking on Whirlpool's Green Tech Forums, FB groups, solarquotes, even asking here. You want a good quality inverter. This is an expensive component, & a point of failure for poorer quality inverters. As you have an unshaded roof, you'd want a string inverter. I'd be looking at a Fronius inverter, number one in my book, or an SMA. Panels don't have to be premium brands, unless you're happy to pay for top quality. But you want something mid-tier or above (don't get sucked into "tier one" propaganda, this has nothing to do with the quality of the panel, just the finances of the manufacturer). A question before determining the appropriate system size. Is this a forever home, or do you at least plan to be there for quite a few years? You're blessed with 90sqm of north facing roof, a huge amount of real-estate! It would be a pity to waste it. Most people say go big! How big will depend on your circumstances. Your planned time in the house, your energy consumption, your finances, your location (power distributors rules for system sizes & feed-in-tariff), whether you have single phase or three phase power. I'm assuming, that as you're considering solar, you'll be in the home for the medium term at least. So the smallest system I'd consider is a 5kW inverter, oversized with 6.6kW of panels. The rules state that the panels can oversize the inverter by 33%. So 6.65kW the maximum allowable. As panels are cheap, an the STC's (rebate) are calculated on panels size, not inverter size, oversizing up to 133% of the inverter size is worth doing. This will increase production in less than ideal conditions (winter, cloud & rain, early mornings & late evenings). In ideal conditions oversizing will produce the same power as a non-oversized system, as a 5kW inverter can never output more than 5kW. Firstly, this may be the maximum system size for you, or it may be possible to have a bigger system. I'm not an expert on WA, but looking at the below article (written last year), it looks like sizing rules vary depending on your local distributor. https://www.solarchoice.net.au/blog/sol ... by-network It looks like Western Power is the local distributor, & allows 10kW for single phase, 30kW for three phase. That's big! You'd also need to find out if there is any export limiting (where you can generate lots of electricity, but there is a limit on the amount you can expert back to the grid). I don't see any reference to export limiting. You have the roof space for a lot of panels, at least 50. Average panels nowadays are around 330W. So a 50 panel system would be 16.5kW. You may not want to go this big, due to finances, & the low FIT rate in WA. But increasing the system size beyond 5kW/6.6kW is certainly worth looking at. Labour is a large proportion of the install cost. Panels are cheap, & upping the inverter size doesn't increase the cost much. So doubling the system size doesn't double the cost. At a guess, I'd probably look at around an 8kW inverter, 10.6kW of panels. It's very dependent on your finances (though solar is a great investment, with very good returns), & your power usage. Usage is likely to be quite high for a young family of four. But power usage is very dependent on the energy efficiency of your home. Whether you orientated it correctly (with north facing living areas & limited western glazing), designing it around "passive solar principles. Whether you increased insulation levels. I really hope you've chosen an efficient floor plan, that is orientated correctly. This is absolutely free, & has a huge effect on comfort & future bills. I hope you've increased insulation levels above or very poor minimum standards. Also quite cheap to do at the time of the build. Electricity usage will also vary depending how you heat & cool your home, & heat your water (which I'll discuss below). The efficiency of your appliances. Your usage patterns (such as drying clothes in the dryer). Whether you have a pool, very power hungry luxuries. Also think of the future. EV cars are just around the corner. You solar system will be in years. Currently EV's consume around 0.2kWh of electricity per km. Drive 20km a day, that's 4kWh. 2 cars, that's 8kWh. Which is a substantial amount (similar to hot water for a family of 4). Which finally brings me to hot water! Although solar hot water (SHW) is efficient, & the systems are generally long lasting, they're also expensive. They're really only worth the investment in northern Australia, where they don't require boosting. Further south they'll need boosting in winter. Either by gas (which I wouldn't install, discussed below), or by electricity (usually after the sun goes down & your solar PV isn't generating. Another extremely efficient option for hot water is a heat pump. Like SHW these are expensive, but also gain the STC (rebate). Heat pumps get a bad rap with some plumbers, due to some very poor systems (particularly Dux) years ago. But things have changed since then, & there's more some very good units like Sanden (6 year warranty), Reclaim, Stiebel Eltron, among others. Though it's still worth only sticking with the reputable brands. You probably already own a couple of heat pumps, they're certainly not new. Your refrigerator, & your AC. They're also very efficient, reverse cycle AC is the cheapest form of heating (with efficiencies up to around 500%)! How water heat pumps are very efficient (around 300-400%), so will use around a quarter of the energy of a standard electric hot water system. For a family of four, an electric HWS may use to to 8kWh or electricity, while a heat pump will use around 2kWh. But like the SHW, heat pumps are expensive. So it's worth looking at the cost, & the rebates you'll receive, & compare it to the cost of a standard electric HWS. For a difference of $3,000 you may be able to add an additional 3-5kW of solar panels. Which will average 12-20kWh of generation a day, much more than 6kWh the heat pump will save. I do love heat pumps, & choosing the greenest option, but the finances mightn't stack up of your can increase the size of your solar PV system. I'm any case, I'd be choosing some for of electric water heater, standard element or heat pump. I'd be choosing electricity for all my appliances. Building an all-electric home! Are you planning on installing gas, for cooking, heating or considering it for hot water? I'd be ditching gas altogether! Having no gas connection, & no daily service fees, will save hundreds & hundreds of dollars a year! Reverse cycle AC is now the cheapest form of heating. Getting much cheaper than gas. Induction cooking is easy to clean, of very responsive, & with very good control of the temperature. It gets rave reviews from many, many people. There's really no need for gas at all. Your wallet & the environment will thank you If you're on FB, & interested in this approach, it's worth joining the My Efficient Electric Home (MEEH) group. Wow, long post. Quarantine, without having time for tik tok videos Best of luck with your build. Re: Which Solar Package to Choose? 8May 06, 2020 12:00 pm ddarroch I'm probably going to throw a spanner in the works, but I'd go for neither option. OPTION C: Larger solar PV post-build, some type of electric hot water. I wouldn't be getting solar hot water in Perth, or getting my solar PV installed by the builder. Here's why. Most things I've read say it's a much better idea to get solar SV installed after the build. This is because the builder will just sub out the solar installation, & you have no control over who installs the system. Most likely the builder subs out the work to the lowest cost quote, not the best quality system (& install). Ranked, order of importance, it's; 1. Quality of installer. 2. Quality of the inverter. 3. Quality of the panels. 4. Mounting & other components. It's very important to choose a good quality local installer. Who is well reviewed, & has a moderately long business record. You don't want a poorly installed system, that is more likely to fail. You certainly don't want warranty issues, only to find the business has closed down (often phoenixing, & starting up as another business). How does troubleshooting & warranties for solar PV work with the builder? Do you chase up the builder, or have contact details for the installer? Looking at problems people have remedying issues with their build once they've moved in, I'd hate to be chasing a builder for a solar PV system that has stopped working a few years down the track. As for the gear. You haven't mentioned the brand of inverter or panels. Have you been given this information? Or are they going to plonk any cheap Chinese gear on your roof? So I'd be installing the solar PV system post-build (maybe getting the builder to install conduit for the system, you'd have to discuss this with your chosen installer & builder). Choose a local company, that has been doing good quality installs for many years. It's pretty easy to find out this info, looking on Whirlpool's Green Tech Forums, FB groups, solarquotes, even asking here. You want a good quality inverter. This is an expensive component, & a point of failure for poorer quality inverters. As you have an unshaded roof, you'd want a string inverter. I'd be looking at a Fronius inverter, number one in my book, or an SMA. Panels don't have to be premium brands, unless you're happy to pay for top quality. But you want something mid-tier or above (don't get sucked into "tier one" propaganda, this has nothing to do with the quality of the panel, just the finances of the manufacturer). A question before determining the appropriate system size. Is this a forever home, or do you at least plan to be there for quite a few years? You're blessed with 90sqm of north facing roof, a huge amount of real-estate! It would be a pity to waste it. Most people say go big! How big will depend on your circumstances. Your planned time in the house, your energy consumption, your finances, your location (power distributors rules for system sizes & feed-in-tariff), whether you have single phase or three phase power. I'm assuming, that as you're considering solar, you'll be in the home for the medium term at least. So the smallest system I'd consider is a 5kW inverter, oversized with 6.6kW of panels. The rules state that the panels can oversize the inverter by 33%. So 6.65kW the maximum allowable. As panels are cheap, an the STC's (rebate) are calculated on panels size, not inverter size, oversizing up to 133% of the inverter size is worth doing. This will increase production in less than ideal conditions (winter, cloud & rain, early mornings & late evenings). In ideal conditions oversizing will produce the same power as a non-oversized system, as a 5kW inverter can never output more than 5kW. Firstly, this may be the maximum system size for you, or it may be possible to have a bigger system. I'm not an expert on WA, but looking at the below article (written last year), it looks like sizing rules vary depending on your local distributor. https://www.solarchoice.net.au/blog/sol ... by-network It looks like Western Power is the local distributor, & allows 10kW for single phase, 30kW for three phase. That's big! You'd also need to find out if there is any export limiting (where you can generate lots of electricity, but there is a limit on the amount you can expert back to the grid). I don't see any reference to export limiting. You have the roof space for a lot of panels, at least 50. Average panels nowadays are around 330W. So a 50 panel system would be 16.5kW. You may not want to go this big, due to finances, & the low FIT rate in WA. But increasing the system size beyond 5kW/6.6kW is certainly worth looking at. Labour is a large proportion of the install cost. Panels are cheap, & upping the inverter size doesn't increase the cost much. So doubling the system size doesn't double the cost. At a guess, I'd probably look at around an 8kW inverter, 10.6kW of panels. It's very dependent on your finances (though solar is a great investment, with very good returns), & your power usage. Usage is likely to be quite high for a young family of four. But power usage is very dependent on the energy efficiency of your home. Whether you orientated it correctly (with north facing living areas & limited western glazing), designing it around "passive solar principles. Whether you increased insulation levels. I really hope you've chosen an efficient floor plan, that is orientated correctly. This is absolutely free, & has a huge effect on comfort & future bills. I hope you've increased insulation levels above or very poor minimum standards. Also quite cheap to do at the time of the build. Electricity usage will also vary depending how you heat & cool your home, & heat your water (which I'll discuss below). The efficiency of your appliances. Your usage patterns (such as drying clothes in the dryer). Whether you have a pool, very power hungry luxuries. Also think of the future. EV cars are just around the corner. You solar system will be in years. Currently EV's consume around 0.2kWh of electricity per km. Drive 20km a day, that's 4kWh. 2 cars, that's 8kWh. Which is a substantial amount (similar to hot water for a family of 4). Which finally brings me to hot water! Although solar hot water (SHW) is efficient, & the systems are generally long lasting, they're also expensive. They're really only worth the investment in northern Australia, where they don't require boosting. Further south they'll need boosting in winter. Either by gas (which I wouldn't install, discussed below), or by electricity (usually after the sun goes down & your solar PV isn't generating. Another extremely efficient option for hot water is a heat pump. Like SHW these are expensive, but also gain the STC (rebate). Heat pumps get a bad rap with some plumbers, due to some very poor systems (particularly Dux) years ago. But things have changed since then, & there's more some very good units like Sanden (6 year warranty), Reclaim, Stiebel Eltron, among others. Though it's still worth only sticking with the reputable brands. You probably already own a couple of heat pumps, they're certainly not new. Your refrigerator, & your AC. They're also very efficient, reverse cycle AC is the cheapest form of heating (with efficiencies up to around 500%)! How water heat pumps are very efficient (around 300-400%), so will use around a quarter of the energy of a standard electric hot water system. For a family of four, an electric HWS may use to to 8kWh or electricity, while a heat pump will use around 2kWh. But like the SHW, heat pumps are expensive. So it's worth looking at the cost, & the rebates you'll receive, & compare it to the cost of a standard electric HWS. For a difference of $3,000 you may be able to add an additional 3-5kW of solar panels. Which will average 12-20kWh of generation a day, much more than 6kWh the heat pump will save. I do love heat pumps, & choosing the greenest option, but the finances mightn't stack up of your can increase the size of your solar PV system. I'm any case, I'd be choosing some for of electric water heater, standard element or heat pump. I'd be choosing electricity for all my appliances. Building an all-electric home! Are you planning on installing gas, for cooking, heating or considering it for hot water? I'd be ditching gas altogether! Having no gas connection, & no daily service fees, will save hundreds & hundreds of dollars a year! Reverse cycle AC is now the cheapest form of heating. Getting much cheaper than gas. Induction cooking is easy to clean, of very responsive, & with very good control of the temperature. It gets rave reviews from many, many people. There's really no need for gas at all. Your wallet & the environment will thank you If you're on FB, & interested in this approach, it's worth joining the My Efficient Electric Home (MEEH) group. Wow, long post. Quarantine, without having time for tik tok videos Best of luck with your build. Thanks for your very thorough reply!! I am sure it will be helpful to anyone else who stumbles over this thread. Hopefully you are out of quarantine now We have decided to install solar after the build. Looking at investing in a Fronius or SMA inverter. Not sure of size - finance dependent. The overall idea would be to get a decent sized inverter and then add more panels to the 133% threshold over time. We plan to live in this house for 10 years, give or take. Will look more into the electric HWS. Certainly interested to go down that path it works out to be beneficial. We will keep a gas connection to the house as have gas appliances and doubt package builder will have similar electric options. Thanks again!! I looked into it a few years ago and my conclusion was to just build a carport that will support panels and get a system installed separately. The company I looked at had… 1 6525 Black on light wood does look good. Not sure if it will be as long lasting as a steel finish? 6 6419 brokers will also be in a position to get you a better rate than the advertised rate most times. 6 7620 |