Floating solar panels

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kingdragonfly

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#245409 2-Feb-2019 10:21

I thought floating solar panels are interesting. I don't think its been done here.

I read that in Japan it is used to save land, reduce algae growth in turpid, stagnant ponds.

Anyhow could be useful on farms here. There are 3,820 lakes with a surface area larger than one hectare.

Floating solar power plant:
interview with Vivek Jha

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#2171764 2-Feb-2019 13:10

It still doesn't solve the biggest problem with solar in NZ. Which is peak demand occurring during winter evening.

And there are some man made lakes in NZ that are used as part of sewage treatment systems. They need to remain exposed to the sun.

Tracer

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#2171778 2-Feb-2019 13:26

Aredwood: It still doesn't solve the biggest problem with solar in NZ. Which is peak demand occurring during winter evening.

Yup, solar cannot cover this at all, and wind can only cover a relatively small portion if you expect stable supply.

afe66

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#2171780 2-Feb-2019 13:34

The idea of covering our lakes with solar panels is a definite no for me. Lakes aren't wasted space.

We have probably tens of millions square meters of industrial roof tops without anything on them.
Panel these. This has added benefit of already being connected to power grid and not need cables and infrastructure to be built near lakes.

empacher48

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#2171855 2-Feb-2019 15:26

I was reading something a few weeks ago, which said that if the total surface area of solar panels in NZ was the same surface area as Rangitoto Island, and we have about 200m2 of battery storage we wouldn’t need to have any fossil fuel electricity production.

It will be interesting to see how true that really is.

PolicyGuy

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#2171921 2-Feb-2019 17:05

afe66:
We have probably tens of millions square meters of industrial roof tops without anything on them.
Panel these. This has added benefit of already being connected to power grid and not need cables and infrastructure to be built near lakes.

This

The most effective places to have PV panels are those which are one (or maybe two) stories and have peak electricity usage during the hotter parts of the day and year.
Think shopping malls, airports, rest homes & hospitals, some industrials. Anyplace that's air conditioned.
The Sylvia Park mall put in quite a large PV array in 2015 (~250kVA), others should follow suit

Not schools (empty through half the summer, most not air conditioned anyway), residential homes (usually empty 7am to 6pm)

Jase2985

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#2171932 2-Feb-2019 17:45

PolicyGuy:

Not schools (empty through half the summer, most not air conditioned anyway), residential homes (usually empty 7am to 6pm)

but schools etc in the summer can feed back into the grid :) which benifits more people when the school is not using the power, it also benifis the school by offsetting costs.

jlittle

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#2173956 6-Feb-2019 13:19

... the biggest problem with solar in NZ. Which is peak demand ...

... solar cannot cover this at all ...

You guys might like to consider this video from 2017 , a futurist making projections.

Solar doesn't match demand, but solar plus storage matches demand much better and cheaper than the existing power grid approaches (low utilization peaker power stations plus massive transmission infrastructure). It is now supposedly cheaper for new generation in some markets than any other technology. South Australia have saved a lot of money using the Telsa battery because it has matched demand faster than the old grid could.

So in NZ in 2019, is DIY solar plus storage reasonable?

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wellygary

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#2173958 6-Feb-2019 13:38

empacher48: I was reading something a few weeks ago, which said that if the total surface area of solar panels in NZ was the same surface area as Rangitoto Island, and we have about 200m2 of battery storage we wouldn’t need to have any fossil fuel electricity production.

It will be interesting to see how true that really is.

Nah, tell 'em they are dreaming

Accoridng to wiki Rangitoto is 2300 ha,

This farm in India

https://www.alternative-energies.net/kamuthi-solar-power-plant-in-india-is-now-operational/

is 2500 acres (1000ha) and it only puts out 648 MW, Manapouri puts out around 800MW on its own, and last time i looked NZs installed capacity was around 10,000 MW

tdgeek

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#2173959 6-Feb-2019 13:40

Tracer:

Aredwood: It still doesn't solve the biggest problem with solar in NZ. Which is peak demand occurring during winter evening.

Yup, solar cannot cover this at all, and wind can only cover a relatively small portion if you expect stable supply.

Solar is not meant to be the be all and end all of power. Once installed it gives near free power, reducing demand from the current national generation, occasionally giving power back.

There is a solar article today, subsidised installs in Marlborough. Its worth a read just for the "Comments"

https://www.stuff.co.nz/life-style/homed/110293246/man-gets-160-power-bill-for-december-after-fitting-solar-panels

If every residence has solar, and saved money, then that saved money goes back to the economy. The payback at 7-10 years, maybe more, is a good investment.

Aredwood

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#2174040 6-Feb-2019 15:37

tdgeek:
Tracer:

Aredwood: It still doesn't solve the biggest problem with solar in NZ. Which is peak demand occurring during winter evening.

Yup, solar cannot cover this at all, and wind can only cover a relatively small portion if you expect stable supply.

Solar is not meant to be the be all and end all of power. Once installed it gives near free power, reducing demand from the current national generation, occasionally giving power back.

There is a solar article today, subsidised installs in Marlborough. Its worth a read just for the "Comments"

https://www.stuff.co.nz/life-style/homed/110293246/man-gets-160-power-bill-for-december-after-fitting-solar-panels

If every residence has solar, and saved money, then that saved money goes back to the economy. The payback at 7-10 years, maybe more, is a good investment.

Except that a large part of that guys savings are from paying lower lines fees. A big part of the per unit charges actually go to the lines company. But the costs of running a lines network are mostly fixed costs and the cost to meet peak demand.

Getting solar doesn't reduce those costs to the lines company. So lines costs increase, which get loaded onto low income people who can't afford solar. The only fair method long term, is either large fixed daily fees (between $5 and $10 per day depending on the network) or a mixture of capacity based and fixed fees. Per unit charges would then be between 7c to 15c per unit.

And then there is the ”duck” curve. In that peak demand occurs outside of solar peak production. Someone who uses 20 KW/Hr of power per day is considered a low user. Price up a 20KW/Hr home battery bank. Then buy an EV that needs to be charged at night. (because it is at your workplace during the day). Now you need at least a 50KW/hr battery bank. And solar panels only output 10-15% of their rated capacity on cloudy days. So you are going to need far more panels to get enough power. But then you need space for all of those panels and batteries. No good if you live in an apartment or tiny house. And the batteries only last for 5 years or so anyway. So you have to budget for replacement.

In short - Solar is a great option if you are a rich person living in a large home. Who doesn't care about loading extra costs onto poorer people.

Take away the indirect subsidies to solar, and the savings quickly disappear.

PolicyGuy

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#2174043 6-Feb-2019 15:58

Jase2985:
PolicyGuy:

Not schools (empty through half the summer, most not air conditioned anyway), residential homes (usually empty 7am to 6pm)

but schools etc in the summer can feed back into the grid :) which benifits more people when the school is not using the power, it also benifis the school by offsetting costs.

That's all very well & altruistic, but I still maintain that solar PV doesn't make economic sense for a school at current feed-in tariff rates.
If all the installation earns for the two most energy-productive months of the year is the six to eight cents per kWh currently being offered, it completely blows out the economic pay back period.
It's when the solar generation is used on site that the real pay back occurs: that energy "saves" the cost of grid-bought power, say thirty cents per kWh, rather than being exported at a quarter of the value

The average home with two working adults plus some school age children is even worse: they are almost never at home to use the solar power when it is generated. Sure you can have say one load of washing set to start at 11am and one load in the dryer to start at 1pm, and if you have electric hot water set it on a time clock from 9am to 4pm, but the cooking and comfort heating/cooling and the rest of the laundry will be from 6am to 7:30am and 4:30 or 5:30pm until 9 or 10pm.
So you end up selling most of the power at six to eight cents per kWh, then buying it back at thirty cents in the evening.
Economically this is nuts.

I applaud everyone with PV panels on their house roof, but unless they're stay at home retirees or stay at home parents with preschool or home schooled kids, they're not doing themselves any economic favours.

Dingbatt

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#2174051 6-Feb-2019 16:32

But as soon as you say PV + Battery the hit isn’t quite as great. But of course you are probably doubling the payback period. Removes the 4:1 buy sell ratio from the equation though.
I wonder whether using wind, solar, wave and tidal to elevate (sea) water so it can be used when required is an option. I know pumps aren’t particularly efficient, especially pushing against gravity, but the potential energy stored is available to meet load.

“We’ve arranged a society based on science and technology, in which nobody understands anything about science technology. Carl Sagan 1996

tdgeek

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#2174052 6-Feb-2019 16:37

Dingbatt: But as soon as you say PV + Battery the hit isn’t quite as great. But of course you are probably doubling the payback period. Removes the 4:1 buy sell ratio from the equation though.
I wonder whether using wind, solar, wave and tidal to elevate (sea) water so it can be used when required is an option. I know pumps aren’t particularly efficient, especially pushing against gravity, but the potential energy stored is available to meet load.

Doesn’t this mean that all alternatives are incompatible? If we use less generated power by generating our own and using gas, all of these reduce generated usage and cause the same lines fees problems as Andrew outlined for solar PV?

Aredwood

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#2174057 6-Feb-2019 16:49

PolicyGuy:
Jase2985:
PolicyGuy:

Not schools (empty through half the summer, most not air conditioned anyway), residential homes (usually empty 7am to 6pm)

but schools etc in the summer can feed back into the grid :) which benifits more people when the school is not using the power, it also benifis the school by offsetting costs.

That's all very well & altruistic, but I still maintain that solar PV doesn't make economic sense for a school at current feed-in tariff rates.
If all the installation earns for the two most energy-productive months of the year is the six to eight cents per kWh currently being offered, it completely blows out the economic pay back period.
It's when the solar generation is used on site that the real pay back occurs: that energy "saves" the cost of grid-bought power, say thirty cents per kWh, rather than being exported at a quarter of the value

The average home with two working adults plus some school age children is even worse: they are almost never at home to use the solar power when it is generated. Sure you can have say one load of washing set to start at 11am and one load in the dryer to start at 1pm, and if you have electric hot water set it on a time clock from 9am to 4pm, but the cooking and comfort heating/cooling and the rest of the laundry will be from 6am to 7:30am and 4:30 or 5:30pm until 9 or 10pm.
So you end up selling most of the power at six to eight cents per kWh, then buying it back at thirty cents in the evening.
Economically this is nuts.

I applaud everyone with PV panels on their house roof, but unless they're stay at home retirees or stay at home parents with preschool or home schooled kids, they're not doing themselves any economic favours.

Since a school is not a residential home, it will be on a business power pricing plan. This means higher fixed fees and lower per unit costs. And in turn, that means that even for the solar power that you self consume, lower savings. And generally, the larger the size of your electricity connection, the larger your daily fees. But the lower your per unit rate.

Some of the larger schools might only be paying 10c or so per unit of power. So very low savings for self consumed power, yet the solar won't save any money on the fixed fees.

And if you do have solar on a residential connection. Your savings are based on the indirect subsidies not being removed. Which is a risky basis for a long term investment. Especially as high power prices are always an election issue. And since the current subsidies hurt larger households the most. They are especially bad for Maori and Pacific islander households. (who are also the group's that would be less able to get solar installed). They are also a tax on charging EVs at home.

So only a matter of time before they get scrapped. Once more people realize how indirectly racist the low user regulations are.

driller2000

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#2174063 6-Feb-2019 17:06

Dingbatt: But as soon as you say PV + Battery the hit isn’t quite as great. But of course you are probably doubling the payback period. Removes the 4:1 buy sell ratio from the equation though.
I wonder whether using wind, solar, wave and tidal to elevate (sea) water so it can be used when required is an option. I know pumps aren’t particularly efficient, especially pushing against gravity, but the potential energy stored is available to meet load.

Pumped hydro is exactly that - with numerous existing installs and many potential project sites being investigated across the globe:

https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity

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