Can solar be a good investment?

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Talkiet

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#1670335 13-Nov-2016 23:04

All excellent points... I do have a very detailed view of my overall electrical consumption... Probably the only big thing I am missing is the impact switching back to electrical water would have... I'm aware diverting production to other storage methods instead of battery (heating of various types - or cooling!) is more efficient.

I'm not familiar with the details but I would have been staggered if we didn't have as many possible regulations and rules as possible without making solar actually impossible to install here in NZ.

One question though as it seems you're pretty familiar with the area... Apart from the obvious actual practical safety considerations, are there are rules around building an offgrid system if it's not a primary circuit for a dwelling? I'm thinking (in theory) about a panel and inverter to top up a UPS...

Presumably the solar battery chargers for car batteries don't require any certifications and are pretty safe...

At the other end if I put 30Kwh of panels and a room full of batteries it could easily kill me - but as it's not grid connected I have no idea if there's any regulations or certifications required? (Let's assume DIY and any changes to the dwelling were carried out in accordance with appropriate building standards)

In a practical sense I am wondering whether a couple of panels and a small inverter would be able to power a UPS to cover communications and cellphone battery chargers etc...

If it's all on a completely isolated circuit to the mains, what are the requirements?

Cheers - N

ps. Usage stats to the ~10 second resolution. It's interesting watching the heat pump come in and out, and you can see when I cooked my burritos for dinner in the oven...

Please note all comments are from my own brain and don't necessarily represent the position or opinions of my employer, previous employers, colleagues, friends or pets.

RUKI

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#1670560 14-Nov-2016 11:01

Stan:

......

What I would like to know is in your situation what would you estimate the payback of a small system like this to be working off the cost of power in your location and your usage habits? Would you change your usage habits if you got solar?

Instead of estimations or assumptions I do prefer to deal with factual data, analyse it and present in a way that you can put your own variables and come to results which interest you.

I share data about solar generation on FB page monthly: https://www.facebook.com/toyotahybridbatteryexperts: the last one is from 1 Nov 2016.

At the end of the year the amount of self-consumed power could be multiplied by the unit price (do not forget to add maintenance component). In my case total is about $0.33/kWh - could be different in yours. And I will add to the stats what was exported to the grid in kWh. Negligible right now as we consume electricity during the day every day.

Those factual numbers will give good idea for similar installs (azimuth, elevation, battery, panels) in Auckalnd. All you will do if your household is similar - get the quote for the system and calculate your ROI.

Hammerer

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#1671017 14-Nov-2016 21:36

TwoSeven:

I havnt looked into it too much, but I think in france for example, one gets a tax credit on solar collector (water) installations and the price of panels is around half a euro per Wp for the bigger panels.

Half a euro would be about 75 cents here so that is really cheap.

I had a quick look at some stats for other countries.

vs Germany

I had a look at German statistics in Recent Facts about Photovoltaics in Germany, update 22 April 2016.

On page 9, the net cost for 10-100 kWp rooftop systems averages to 1,300 Euro per kWp (kiloWatt peak, i.e. output when the PV system is operating at peak capacity) which at ~1.5 NZD/Euro is about $2,000 per kWp.

Looking at the figures that Energywise uses in their solar calculator then it looks like we're on the same sort of economies of scale. If I assume economies at the same rate then it looks like it does approach $2,000 per kWp at about 15 kWp. Are the Energywise figures useful? I don't know but there are solar sites with similar costs, e.g. https://mysolarquotes.co.nz/about-solar-power/residential/how-much-does-a-solar-power-system-cost/

As an aside, how's this for a quote from a 2014 The Guardian article about solar energy in Germany. I added the bold in case you missed the point.

Subsidy cutbacks have been felt across the industry, as the cost of solar power has fallen closer to the cost of fossil fuel energy. From a zenith of $0.90 per kilowatt hour, German feed-in-tariffs that pay people for generating energy from solar have fallen to around $0.20 per kwh today. The guaranteed 20-year tariff offered to early household investors is now a thing of the past.

In NZ dollars that was well over a dollar per kWh.

vs Australia

However, I think the real test for us would be to compare with Australian statistics. They look really cheap compared with us and even compared with Germany.

Australian retail solar system prices

Australian commercial solar system prices

Australia appears to have very low lower system costs. Lots of sun and state subsidies mean they have 1.5 million installations so their scale economies will be much better than NZ. Even so their scale economies are much better than ours even if I adjusted for exchange rate and state subsidies.

vs United States

Apparently, USA margins at 40% are more than twice those in Australia hence the US unit cost at AUD3.50/kWp is nearly twice the Australian price of AUD1.63/kWp. We aren't do too badly on this basis.

http://www.solarchoice.net.au/blog/news/bigger-installer-profits-higher-solar-prices-usa-230916

Tentative conclusion

From this cursory analysis I would say that NZ costs are not unreasonable but there is a case to be made that they could go a lot lower.

xlinknz

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#1671040 14-Nov-2016 22:46

I was looking at a 7KW system 5 years ago, the capital cost since then has dropped 50% but the ROI remains essentially unchanged

Two observations

Never rely on a buy back rate as it may not be there tomorrow
As a work colleague who has a PV system said - think of it as pre paid power...

From my perspective basically there is no certainly in the ROI

tdgeek

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#1671059 15-Nov-2016 07:08

xlinknz:

I was looking at a 7KW system 5 years ago, the capital cost since then has dropped 50% but the ROI remains essentially unchanged

Two observations

Never rely on a buy back rate as it may not be there tomorrow
As a work colleague who has a PV system said - think of it as pre paid power...

From my perspective basically there is no certainly in the ROI

Fair comment. Another way to look at it, is a 10% ROI is a great return. After the 10 year payback, its a much larger return. In that the free power generated less R+M each year, which for a general system may be quite a few hundred or a k the odd year, or the odd 5 years. Battery users, would still need to factor in replacement.

More ideal for those that want to settle long term. if solar (HW, PV, or non PV) became very popular, you may buy a house already equipped as we did, in which case the solar is a sunk cost, and you could put a capital value of zero on it.

PhantomNVD

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#1671069 15-Nov-2016 08:02

Talkiet:

At the other end if I put 30Kwh of panels and a room full of batteries it could easily kill me - but as it's not grid connected I have no idea if there's any regulations or certifications required? (Let's assume DIY and any changes to the dwelling were carried out in accordance with appropriate building standards)

In a practical sense I am wondering whether a couple of panels and a small inverter would be able to power a UPS to cover communications and cellphone battery chargers etc...

The recent Electrical Safety legistalion says less than 250W and 50V is safe for DIY.
Big discussion on the Motorhome forum about this very issue, but lobbying by the Sparky association gets accepted as fact \_0_/

RUKI

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#1671175 15-Nov-2016 10:05

tdgeek:

...... After the 10 year payback, its a much larger return. ....

After 10 years, you would most likely dump the battery and panels. I think 5 year period is more practical goal in this fast moving world.. If something does not pay off in 5 years - too bad.

e.g. Cars depreciate in 5 years (in Business). University study can be finished in 5 years with people relocating after graduation. Other types of fiancial palnning in life are around 5 year periods.

Stan

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#1671559 15-Nov-2016 19:57

Installed cost for a 5kw unit is around $2.20 per watt.

Interesting to see the difference in responses. I am waiting on energywise to give me information how they calculate ROI etc I asked them a few in depth questions.

Solar is not a good investment for everyone but if you are a higher user there is defiantly a case for it.

I am actually a terrible example for a good ROI as myself and my wife are never home during the day.

Exported 108kw last month on my little 1.5kw system.

So around 50% usage.

Aredwood

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#1671629 16-Nov-2016 00:03

@Stan Im guessing that that controlled reading is from a separate meter that supplies your hot water cylinder? If so then some of the solar power you exported, you would have immediately re imported again via the controlled meter. 11.92c per unit gross profit to Genesis. (and some of it to your lines company) But if you get rid of the controlled meter you would then have to pay more for the power used by your cylinder. So a loose loose for you.

As for that 250W limit - What a silly rule. As a fully charged car battery will easily deliver over 1000A into a direct short circuit. It's not going to matter if the solar panel that keeps that battery charged is rated at 300W or 3W. And when you consider the power used by a car starter motor. The test report that came with the rebuilt starter motor for my van. Peak power used by the starter motor was 3.4kW. The test report stated that the battery that was used for testing has 8milliOhm internal resistance. So in theory it would have delivered 1500A in a short circuit.

Stan

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#1672454 16-Nov-2016 22:46

Just got linked to the paper the energywise calc is based off

"From the analysis, the PV system cost needs to fall to about 2.3 $/Wp for the New Zealand wide median NPV to be at zero (i.e. where PV is financially viable for 50% of households), subject to assumptions"

Well that is defiantly possible right now for 3kw+ size systems.

Jimmyshergal

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#1672455 16-Nov-2016 22:55

Not only the price, costs and money,, you need to improve the facilities of using a solar system. I heard that a solar system produce too much heat, and it's a very big issue. What you are going to do about it?

Stan

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#1672457 16-Nov-2016 23:04

Not only the price, costs and money,, you need to improve the facilities of using a solar system. I heard that a solar system produce too much heat, and it's a very big issue. What you are going to do about it?

Produce too much heat??

They produce power. Well PV solar anyway.

Aredwood

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#1674231 19-Nov-2016 16:33

Stan:

Just got linked to the paper the energywise calc is based off

"From the analysis, the PV system cost needs to fall to about 2.3 $/Wp for the New Zealand wide median NPV to be at zero (i.e. where PV is financially viable for 50% of households), subject to assumptions"

Well that is defiantly possible right now for 3kw+ size systems.

That paper said they used retail prices from the Genesis energy website. And they didn't say if they used standard user rates or low user rates. Because the low user rates are artificially higher, They are actually an indirect subsidy for solar. Meaning the breakeven $ per watt install cost will be higher than what it would be if electricity charges were set only by market forces.

Stan

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#1674241 19-Nov-2016 17:12

I have created my own solar calculator.

Please note I am no expert in excel but I would be interested to hear any C&C

https://drive.google.com/open?id=0B0FnEJ_YPcmVN01uUndlbzJtYkU

PhantomNVD

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#1674533 20-Nov-2016 15:03

Google is working on helping people with this....

Project Sunroof:

https://youtu.be/_BXf_h8tEes

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