Solar, central heating and EV

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#2932880 21-Jun-2022 20:53

Awesome, thanks @timmmay. I'll have a good read tomorrow.

One of the major issues we have with ducted is the potential for noise. My wife spent her first 20 years in the one house in a quiet neighbourhood where there would be three calls to emergency services if someone dropped a pin after 8pm.

Our neighbours here installed a heat pump earlier this year, maybe 25-30m away from our bedroom, and it still wakes her up. It sounds like being in an aircraft even during the day and is really frustrating to listen to when we're in the garden.

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#2932881 21-Jun-2022 20:53

martyyn:

Yes, 4-5kW. 12 panels would probably see us generate enough for 8 months of the year but the analysis of where we are shows we'd be selling ourselves short so we'll likely go for 16-18. We have the roof space and the suppliers suggested getting as close to the inverter max as possible for as long as possible throughout the year.

We're keen to look at ducted heatpumps as well but getting people to respond is not easy. I've always thought heating water was more efficient and economical than heating air and pumping that around.

I also remember the fuss when we had our HRV installed years ago that it wasn't heat recovery (it's not) and that the heat pumps attached to them we're rubbish.

But like I said, it's hard to get the pros/cons of each system. More often than not the person who answers the phone knows very little, the person who can answer your questions doesn't return your calls because their too busy and if you do get someone they are often just sales which keep pushing the same stuff you read on their websites.

If anyone has any ideas for ducted heat pumps let me know.

Go as high as your budget, roof and network would allow, otherwise 7-8kW on a 5 or 6kW inverter is probably close to a sweet spot.

There are a lot of threads here around ducted or normal heatpumps so maybe have a look for some of those for example: https://www.geekzone.co.nz/forums.asp?forumid=141&topicid=293285

martyyn

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#2932887 21-Jun-2022 21:02

eonsim:

Otherwise 7-8kW on a 5 or 6kW inverter is probably close to a sweet spot.

Yep, this is what they suggested. Less and we are selling ourselves short with what we are capable of producing, more and we are over capitilising.

Then we just have to decide on whether to add batteries or not. We don't have too many power cuts and it's not usually a problem when we do. But the ability to power the heating for as long as possible into the night is tempting.

They supply battery "modules" of 3.2kW and have suggested we start with three (so 9.6kW of battery).

They've offered to review the system after 6 months and again after 12 months to see if anything needs to be tweaked.

Overall they estimate we will generate about 70-80% of the power we have used the last 12 months so reasonable savings every year.

timmmay

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#2932890 21-Jun-2022 21:33

martyyn:

One of the major issues we have with ducted is the potential for noise. My wife spent her first 20 years in the one house in a quiet neighbourhood where there would be three calls to emergency services if someone dropped a pin after 8pm.

Our neighbours here installed a heat pump earlier this year, maybe 25-30m away from our bedroom, and it still wakes her up. It sounds like being in an aircraft even during the day and is really frustrating to listen to when we're in the garden.

30m away from a modern heat pump you can't tell they're operating, unless maybe it's a Panasonic going full blast. Panasonic are really loud. Daikin or Mitsubishi are good. You might be able to tell its going if you're 10m from the outdoor unit and it's quiet. Make sure the outdoor unit is nowhere near your bedroom though, ideally on the other side of the house if your wife is really sensitive to the noise.

martyyn

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#2932894 21-Jun-2022 21:43

Fair play. Just measured it, it's 20m.

Sensitive doesn't even begin to describe it. I grew up in the city and can sleep through anything.

timmmay

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#2932921 21-Jun-2022 22:17

Foam ear plugs are wonderful things. Much cheaper from Amazon USA. Macks brand, u think they have a women's model.

wazzageek

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#2932929 21-Jun-2022 23:17

Regarding the bedrooms - do you have wall insulation & window furnishings? When we moved into our house, there was no insulation and wooden louvres on the windows.

Since then, we have insulated the ceiling, plus insulmax (pumped in) in the walls, plus "black out" curtains on a south-facing bedroom - the curtains and wall insulation has made the most noticeable difference to the temperature in the bedroom - to the point that Mrs Wazzageek will turn off the heater in the bedroom.

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martyyn

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#2934955 27-Jun-2022 16:30

Two more quotes have come in.

Solar with SolarZero:

We decided to give these guys a try as we know three lots of families who have used them in the last 12 months. I'm always skeptical about "no capital outlay and long contract" deals but they are smart people I know doing this so why not ?

They've come back suggesting 15 panels (generating 7500kWh a year) and a 6.4 kW battery to be charged during the day by solar to take the edge off the PM peak time and be recharged by the grid overnight to handle the AM peak. It offers very little in the way of power cut redundancy but we could have the internet and tv/laptop or two.

$180+gst a month for 20 years. They estimate we would likely save $22k over the 20 years (accounting for grid prices increases). So no outlay and no installation or maintenance costs. Battery will be replaced after 10 years and if we move (very unlikely) they will organise the uninstall and re-install at no cost.

If we bought the other system outright and spent, lets say, $20k for more panels and more batteries and if we saved 70-80% of our power bill as they claim that's $2k a year. Over 20 years that's $40k (excluding power increases) so saving $20k. But there is also the cost of adding $20k to the mortgage, we can pay it off quickly but there's still a cost.

Something doesn't add up, so what am I missing ?

Solarzero say there is no way we will save 70-80% the other guy says Solarzero/Harrisons just want to sell a stock system and have no idea how much you can save !

Central Heating:

The guy was very insistent we pick either gas or heat pump to heat the water before giving a quote and then said he would only install gas ! His reasoning was the heat pump would more than double the quote, it's not as efficient, it would cost more to run and it's noisier.

They came back with 7 radiators (one in each room basically, totaling 9kW), an 18kW boiler, one controller, a Google nest thermostat. $22k all up including install and gst. Estimated running costs of $265 month with gas bottles. That's still much cheaper than what we pay for wood over the winter.

But with no-one else we contacted even willing to answer the phone or return my emails it's all we've got at the moment. I think for $22k we could just buy oil filled heaters and run them on thermostats for a very long time.

martyyn

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#2934956 27-Jun-2022 16:32

wazzageek:

Regarding the bedrooms - do you have wall insulation & window furnishings? When we moved into our house, there was no insulation and wooden louvres on the windows.

Since then, we have insulated the ceiling, plus insulmax (pumped in) in the walls, plus "black out" curtains on a south-facing bedroom - the curtains and wall insulation has made the most noticeable difference to the temperature in the bedroom - to the point that Mrs Wazzageek will turn off the heater in the bedroom.

The bedrooms all have thermal, blackout curtains with two having double celled thermal blinds as well. In the living areas it's horrible plastic blinds but the wood burner has that area at 5000C so it's really not a problem !

richms

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#2934963 27-Jun-2022 16:41

Solarzero are expecting a return on their investment that after tax etc will be decent and worth the rish.

You are not paying tax on the savings, and with banks offering several years 0% for green things you will be well ahead of anything you will get for "free" from a for profit company. Despite all their claims about doing it for the good of the planet, they want a return on their investment.

Richard rich.ms

timmmay

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#2934983 27-Jun-2022 17:12

martyyn:

But with no-one else we contacted even willing to answer the phone or return my emails it's all we've got at the moment. I think for $22k we could just buy oil filled heaters and run them on thermostats for a very long time.

Did you not get anywhere with a ducted heat pump install?

martyyn

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#2934990 27-Jun-2022 17:26

richms:
Solarzero are expecting a return on their investment that after tax etc will be decent and worth the rish.

You are not paying tax on the savings, and with banks offering several years 0% for green things you will be well ahead of anything you will get for "free" from a for profit company. Despite all their claims about doing it for the good of the planet, they want a return on their investment.

Can't begrudge them that, everyone needs to make money.

martyyn

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#2934991 27-Jun-2022 17:27

timmmay:
martyyn:

But with no-one else we contacted even willing to answer the phone or return my emails it's all we've got at the moment. I think for $22k we could just buy oil filled heaters and run them on thermostats for a very long time.

Did you not get anywhere with a ducted heat pump install?

Not yet, the bloke I hoped would do both would only do gas and radiators in the end.

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#2935014 27-Jun-2022 19:00

martyyn:
Not yet, the bloke I hoped would do both would only do gas and radiators in the end.

Gas and radiators in the end 😉😂

Scott3

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#2935075 27-Jun-2022 21:03

martyyn:

Two more quotes have come in.

Solar with SolarZero:

We decided to give these guys a try as we know three lots of families who have used them in the last 12 months. I'm always skeptical about "no capital outlay and long contract" deals but they are smart people I know doing this so why not ?

They've come back suggesting 15 panels (generating 7500kWh a year) and a 6.4 kW battery to be charged during the day by solar to take the edge off the PM peak time and be recharged by the grid overnight to handle the AM peak. It offers very little in the way of power cut redundancy but we could have the internet and tv/laptop or two.

$180+gst a month for 20 years. They estimate we would likely save $22k over the 20 years (accounting for grid prices increases). So no outlay and no installation or maintenance costs. Battery will be replaced after 10 years and if we move (very unlikely) they will organise the uninstall and re-install at no cost.

If we bought the other system outright and spent, lets say, $20k for more panels and more batteries and if we saved 70-80% of our power bill as they claim that's $2k a year. Over 20 years that's $40k (excluding power increases) so saving $20k. But there is also the cost of adding $20k to the mortgage, we can pay it off quickly but there's still a cost.

Something doesn't add up, so what am I missing ?

Solarzero say there is no way we will save 70-80% the other guy says Solarzero/Harrisons just want to sell a stock system and have no idea how much you can save !

Central Heating:

The guy was very insistent we pick either gas or heat pump to heat the water before giving a quote and then said he would only install gas ! His reasoning was the heat pump would more than double the quote, it's not as efficient, it would cost more to run and it's noisier.

They came back with 7 radiators (one in each room basically, totaling 9kW), an 18kW boiler, one controller, a Google nest thermostat. $22k all up including install and gst. Estimated running costs of $265 month with gas bottles. That's still much cheaper than what we pay for wood over the winter.

But with no-one else we contacted even willing to answer the phone or return my emails it's all we've got at the moment. I think for $22k we could just buy oil filled heaters and run them on thermostats for a very long time.

on Solar Zero

Personally, I would be a bit reluctant to sign what is essentially a 20 year lease contract, and also be reluctant to be locked into one energy provider for 20 years. Would want to read that contract really carefully before signing, and consider the impact of stuff like inflation (likely in your favor), and decay of panel efficiency (Not in your favor) over the term of the contract.

On central heating.

Don't go with bottled gas. At the moment a 45kg bottle runs at cira $130. 625kWh burnt at 90% efficiency works out to about 23c/kWh.

Not sure what you pay for power, but I pay quite a bit less than that.

As you say, you could get a series of oil heaters, or some kind of wall mounted electric heaters (combined with some thermostats & timers), and get similar results to radiators, without the upfront cost's, and with cheaper running costs than gas.

There is a reason the installer would have been reluctant to quote for a heat pump driving radiators. Generally such system's don't work that well. Heat pumps are good at making heaps of warm water, but not very good at making very hot water. This means efficiency suffers if you run the heatpump at the kinds of tempratures that radiators sized for a gas system would require. Ideally you would do underfloor hydronic heating, but that is hard to retrofit. Only other alternative is massively oversized radiators (adds cost & bulk), or fan forced radiators.

As such most retrofitted heat pump systems you see are the ducted type.

You could also consider a bunch of mini split high wall units instead of central heating. These are the most efficient option, and the Mitsubishi electric unit at the place I stayed this weekend was really quiet.

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