Do personal PV panels make sense considering the grid "cleanliness"?

[GreatWhiteWine]

TL;DR Summary

What if your country grid is already 100% low carbon, does it make sense to add PV panels to your house that have a non negligible carbon footprint from their manufacturing?

Hello Physics Forums!

It is only my second post here, so sorry if I am not perfectly following the rules...

We were wondering with some colleagues a few hours ago, what is the threshold where PV panels are adding a carbon footprint to the electricity generated on the grid considering the carbon footprint of the other electricity "generators".

Let's say we have a country with a perfectly carbon-free electricity grid (I know it doesn't exist and will most probably never exists), adding PV panels to generate electricity will then add carbon because of its manufacturing carbon footprint, right?

No let's go to the other end of the problem, what if we have a country that use 100% coal generated electricity, by adding PV panels, we are removing a really small percentage of the electricity generated with coal and once the carbon footprint of the PV panels manufacturing is taken into account, every kWh generated from the solar panels will then reduce the total carbon emission right?

So now, the big question, is there a way to know if we are adding carbon to our grid total emission by buying PV panels considering the energy sources already in use? For example: in France, approximately 70% of the electricity is coming from nuclear plants (which is a relatively low-carbon energy source even when including the construction and maintenance emissions compared to a coal plant), does it make sense for French people to buy solar panels for their houses considering the carbon footprint coming from the manufacturing of the panels?

Or is it simple as saying, if your country is using high carbon energy like coal, gas or oil then it is always less emitting to add solar panels? (Not taking into account the non-controllable aspect of solar panels).

I hope to be clear enough,

Have a great day!

 

[Baluncore]

If you install PV panels, the power you do not buy from your country, can be sold to where fossil fuels are used to generate electricity.

The carbon required, and the cost of manufacturing PV panels, is often overestimated by the fossil fuel lobby.

As fossil fuel vehicles are replaced with EV, electrical power generation and distribution will become a limiting factor. Any power generated locally will allow more EV, and will reduce the distribution line losses.

 

[anorlunda]

Any power generated locally will allow more EV, and will reduce the distribution line losses.

The bookkeeping makes statements like that hard to prove. In this case, EVs add more demand to the distribution. Only if EVs are charged by PV during the peak solar hours, does it reduce distribution demand.

I expect a crisis in the projected numbers of EVs in the next decade because of our lack of infrastructure to charge them. Power capacity is one thing, but the capital cost of charging stations is huge. In some cities, people do not have garages or driveways, almost all cars have to park on the streets. That means one charging station for every parking space. Ay ay ay.

 

[Rive]

Any power generated locally will allow more EV, and will reduce the distribution line losses.

With the usual separation of living and working areas in cities PV installed at home is actually may be rather a trouble than help.

 

[Baluncore]

With the usual separation of living and working areas in cities PV installed at home is actually may be rather a trouble than help.

You are assuming that the EV is used to commute to work in the city, during the day. That commute should be done by public transport, which also avoids the cost of parking.

The EV can be charging from PV at home in the suburbs during the day. It is then available to run about the suburb, shopping and doing the school run. The EV could also be used for shift work in the city overnight, when public transport is less available.

 

[GreatWhiteWine]

Good morning all!

Thanks for your answers, I have found a great article largely answering my initial question: https://www.carbonbrief.org/solar-wind-nuclear-amazingly-low-carbon-footprints/

Here is the conclusion, the last sentence is quite interesting:
Contrary to the claims of some critics, today’s research shows that the hidden emissions due to building wind turbines, solar panels or nuclear plants are very low, in comparison with the savings from avoiding fossil fuels.

“Some critics have argued renewable energies could come with high hidden greenhouse gas emissions that would negate their benefits to the climate. Our study now shows that the opposite is true,” Luderer says in a statement.

In fact, the indirect lifecycle emissions in a 2C pathway are much lower than in a world without climate policy, where methane leaks during coal and gas extraction are significant.

The paper says:

“The indirect greenhouse gas emissions induced by upscaling wind, solar and nuclear power are small compared with other emissions sources, and thus do not impede the transformation towards climate-friendly power supply.”

While small, these indirect emissions become comparatively significant over time, as direct emissions from power plant chimneys fall towards zero. Hertwich tells Carbon Brief: “If you want to get to zero [emissions], this is part of the challenge you need to overcome.”

 

[DaveE]

The EV can be charging from PV at home in the suburbs during the day. It is then available to run about the suburb, shopping and doing the school run. The EV could also be used for shift work in the city overnight, when public transport is less available.

Yes, but the market niche of people who can charge during the day with their own solar panels and drive at night is insignificant. In fact, the opposite is usually the case. So they generate power when they don't need it and use power when they can't generate it themselves. Clearly storage is required. Where I live (me, actually) that storage is via the grid, on-site batteries are way too expensive in comparison.

 

[Baluncore]

Yes, but the market niche of people who can charge during the day with their own solar panels and drive at night is insignificant.

I see an increase in charging and using for short trips during the day.
The use of private vehicles for commuting will fall as communications and public transport improve. You might not change your behaviour significantly, but the next generation of teenagers will.

 

[russ_watters]

Let's say we have a country with a perfectly carbon-free electricity grid (I know it doesn't exist and will most probably never exists), adding PV panels to generate electricity will then add carbon because of its manufacturing carbon footprint, right?

This assumes that a solar panel installed on your house takes more carbon to accomplish than a solar panel installed by a power company. That's probably false and even if true the difference will be miniscule compared to the carbon offset from a carbon electricity source. Single digit percentages at most.

 

[anorlunda]

Where I live (me, actually) that storage is via the grid, on-site batteries are way too expensive in comparison.

That's cool for you. Just remember that the net billing system is not sustainable as the percent PV on the grid gets larger. As you say, they are providing you with a free battery and neighbors who don't have PV are paying the costs. They will be forced to revoke net billing one of these days.

 

[russ_watters]

That's cool for you. Just remember that the net billing system is not sustainable as the percent PV on the grid gets larger. As you say, they are providing you with a free battery and neighbors who don't have PV are paying the costs. They will be forced to revoke net billing one of these days.

Hopefully not a hijack...

I feel like this is a huge and underreported problem with rooftop solar. I think people tend to calculate payback based on the current rate/incentive structure, but have no idea when or how that structure might change in the future. It's a financial landmine.

Rooftop solar feels like a better idea than it really is, to me.

 

[Baluncore]

We no longer have "net energy metering" here on this hydroelectric island.
We pay a fixed network connection fee, and more for the energy we buy from the State.

The State built an expensive HVDC line to the mainland. Then signed up a private company to operate it. Our power costs immediately doubled, because fossil fuel energy prices were higher on the mainland. Then all our storage dams were empty at the end of the rainy season. Someone had sold our entire reserve of water, as premium Green Power over the HVDC link for a quick buck. Your guess is as good as mine as to who paid for the banks of diesel generators that were imported to make up the shortfall through that summer.

The HVDC line had been operated hot at 20% overcapacity, so it failed. I initially thought that was the best thing that had happened for us islanders in a long time. Unfortunately, the State quietly paid to fix the cable, so their friends in business could continue the surreptitious sale of the State's power asset.

Originally, the State paid us the same for our excess PV as they charged for hydropower. Then they cut the rate they pay from 100% to 33%. Previously, I could store my excess energy automatically, by delaying the fall of water through the turbines. Now, that storage is only 33% efficient. In effect, I am paying a 66% state tax on my excess power recycling. Cryptocurrency mining during the day, would be a more productive use of my excess.

A storage battery would be expensive, so I did a costing on building my own pumped storage system. But then I realised that over the last 50 years, I had already paid to build a big communal one, the State hydroelectric system.

If I purchased an overnight storage battery, or built another pumped hydro system, I would need to recover the cost. I could do that simply by eliminating the network connection fee, and become independent of the State system.

We are but pawns in this political rort.

 

[anorlunda]

You're not alone. The province of Ontario, Canada. The US state of California. The country of Norway. are among those governments who negotiated themselves very bad power deals. Also Germany is paying premiums to coal mine/coal plants to restart. Engineers can work on costs, but when it comes to prices nobody can mess it up more than politicians. I risk being political here, but it works best when we are able to put the decision authority in the hands of someone other than politicians.

 

[Baluncore]

I risk being political here, but it works best when we are able to put the decision authority in the hands of someone other than politicians.

Works the best for whom I wonder?
Our electricity grid is regulated from behind the State "Department of Premier and Cabinet", which is quite political and opaque.

 

[Rive]

... public transport ...

Well, since it's not really a hijack anymore: I do that for 100+ km almost every day, for 20+ years already. I'm kind of lucky, since I have only myself to deliver and basic shops are en route, so not much time wasted. Kind of good, that you can occasionally sleep or read or surf on the net (though privacy is completely missing).

The bad thing is, that it's 12 hours away from home. At winter when I step out of the garden it's dark, and when I arrive home it's already dark again.

I don't know how long I'll be able to do this but a job closer to home (with significantly lower salary) is considered.
I can completely understand people who prefer the improved mobility of cars.
I think the mobility available for the masses is a great asset we should not abandon - especially, since we actually do not need to.

Simply issuing PV licences based on the local daytime demand and network capabilities would just do.