New House Build Considering Solar Power

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aiyaznz

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#190989 19-Jan-2016 11:36

Hi Guys

My family is building a new house and we have 5 adults and 2 children in the house. We got opinion of a solar company whether it is a good idea to install solar system as the sell back rates are crap. We were explained that it in our best interest to get a 5KW system based on our current situation as we were consuming 420KW electricity and 720KW gas to run our house last month. Our house that we will be building is fairly north facing. He explained that we would generate 25KW on average per day and that we should run a cable from each of the heavy electricity using devices (hot water cylinder, induction stove, heat pump, deep freezer, etc) to the switch board seperately using microinverter cables and use elios system to control the excess. He mentioned to get an import export thing that sells the excess back which I cant remember the name off. We were planning to use infinity water heater for hot water and gas central heating aswell as gas stove. Will it be more cost effective to get induction stove, electric heat pump and induction stove compared to gas alternatives? He also explained that if we wanted battery to wait for enphase AC battery. What are your thoughts and suggestions as to what we should do. Is it worth spending more on the electric alternatives or is gas more efficient?

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#1474461 19-Jan-2016 11:39

If you use induction stoves and heat pumps I wonder if solar will have the capacity to deliver the power you need when you need it. With battery storage, sure, otherwise not sure. Same with infinity if it's electric instant hot water, if you have solar then a hot water cylinder may make more sense as it's effectively an energy storage device and can be heated when the sun is shining. Induction stoves are great though. I think some storage, even if a small amount, is potentially important to making use of solar.

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#1474467 19-Jan-2016 11:47

If you are going to have you hot water, heating and cooking on gas, you are going to have to work fairly hard to make Solar stack up,

richms

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#1474498 19-Jan-2016 12:18

Solar only works if you can use it yourself when it is made. Do you cook when the sun is out often? I dont for sure.

Richard rich.ms

vexxxboy

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#1474505 19-Jan-2016 12:28

check out these guys, they seem to have some good deals . Free quote.

https://www.harrisonsenergy.co.nz/solar?gclid=COWxlJrBtMoCFQuCvQod7twO9w

Common sense is not as common as you think.

richms

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#1474516 19-Jan-2016 12:32

The only one that can really be micro-managed to ensure you use all that is available is the hot water. Possibly underfloor heating which isnt so useful in summer to have.

You cant crank back the stove when you are using it because a cloud goes over, and other technology isnt there yet for load shedding. There are plenty of hot water diverters available that will cut back the power to it as you start to import power duing sun hours, I will be looking into that next year since my "2.1" kw install will barely cover my base loading so Im not too worried about a little bit of export happening.

Richard rich.ms

tchart

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#1474519 19-Jan-2016 12:38

We are almost finished our new build. I looked hard and long at solar and it just didn't stack up unless you were home during the day (everyday)

As you and others have stated our issues were similar;

1) Low buy back price when feeding into the grid.

2) Storage of power is complicated and expensive in its own right.

3) Payback was literally 10+ years.

4) No government incentive (they have in Oz I believe).

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timmmay

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#1474523 19-Jan-2016 12:42

Friend of mine has solar, no storage, and sells back to the grid. Selling to the grid is a waste of time, you get so little for it, and export relatively little. It only makes sense for him because he has two hot water cylinders and a spa - in winter it really reduces the hot water costs, in winter it easily heats it all and runs other bits and pieces. Thing is his savings aren't that much more than what I got from switching to Flick energy and shifting some use to off peak - hot water heating for example.

richms

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#1474526 19-Jan-2016 12:50

I calculated 7 years when I did the numbers, but that spreadsheet has been messed with since then so cant re-do it with current interest rates or power prices, but I dont think it would have changed much. My roof is a 45 degree one facing north east. Morning power is more use than afternoon so it pays to think about that.

Richard rich.ms

mattwnz

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#1474596 19-Jan-2016 13:30

timmmay: If you use induction stoves and heat pumps I wonder if solar will have the capacity to deliver the power you need when you need it. With battery storage, sure, otherwise not sure. Same with infinity if it's electric instant hot water, if you have solar then a hot water cylinder may make more sense as it's effectively an energy storage device and can be heated when the sun is shining. Induction stoves are great though. I think some storage, even if a small amount, is potentially important to making use of solar.

Can you hook up solar straight to the household supply, without any storage capacity at all? There would surely be big fluctuations during the day, depend on the amount of sun. Sure, you can do it to water heaters, because fluctuations don't really matter. But otherwise I presume you would need a battery to use as a capacitor which allows you to smooth out the power. I know someone who has had a huge solar array installed on their roof, has two big invertors, but they sell all back to the power company for about 5c per unit. They plan on buying some tesla batteries for about 10k in the future to then go off the grid. But I can't see how it really stacks up, as you have all that capital in a system. It was funny watching Made in New Zealand the other night, when they were going though the building of NZs power stations, and they said back in the 60's, 70's, that NZ would have so much power supply, that it wouldn't be worth charging, and everyone could have free power.

richms

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#1474599 19-Jan-2016 13:33

That is how most people have their solar, just try to use the most of it you can. Batteries do not stack up at all when power is a flat rate no matter what the supply and demand are doing. Once everyone is being billed like flick are pioneering, then using battery for moving your usage may make sense, but no way at all now.

Richard rich.ms

Aredwood

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#1474764 19-Jan-2016 16:49

Is natural gas avilable for your new build?

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#1474768 19-Jan-2016 17:02

Solar won't be economic unless the electricity it's producing during the day is being used. In many cases the savings are equal to the pace of annual price drops for solar PV installations so it may be more economic to go without it for a few years. Savings for direct solar hot water are similar but it costs far less or should cost far less.

I would prefer heat pump central heating as gas can't cool you in summer and dehumidify the air. Hot water heat pumps can heat underfloors and supply hot water but not the other functions except possibly Daikin's. Think about a heat reclaim ventilation system with a good filter to deal with air quality and winter dampness although that may not be much use if you're in a high smoke area.

Induction is a very different style of cooking and it needs special pots and pans. You can run gas hobs off bottles if you don't have mains gas. As induction uses huge amounts of electricity at once it won't benefit much from solar panels especially when cooking in the evening. Flush mount gas hobs would be my preference, F&P and Smeg sell them.

There are many small factors involved in these decisions.

Mark

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#1474897 19-Jan-2016 21:14

For reference this is what the 3kW Vector SunGenie did for us this month (16 panels on the roof and roughly a 10kW battery in the garage) :

You REALLY need a way to store the power, exporting to the grid is almost pointless now since all the electricity retailers decided together to slash the buy price, take a good look at the Tesla power wall, it's not the highest capacity system you can get but it is quite high tech and doesn't take much space.

edit. It Would help I described the picture :-)

The line is power coming in from the sun, grey is grid power being used, green is solar generated power being used (both from battery and direct from panels to house), blue is power being exported. "Solar usage" is how much power the house used that came from the sun/battery, "Solar Export" is amount of surplus power exported back to the grid, "Total Usage" is how much the house used (solar+battery+grid).

Jase2985

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#1474904 19-Jan-2016 21:26

could you make the picture bigger please @Mark ?

Mark

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#1474922 19-Jan-2016 21:30

Jase2985:

could you make the picture bigger please @Mark ?

Try now .. it's clickable to the full size image, didn't want to do the full size in the post as it'll put scrolly bars on peoples browser :-)

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