What would you do about when the sun doesn’t shine?
17TW is a lot of batteries. And if 17TW is the 24hr average, you would need to generate 34TW, of which half would charge the batteries when the sun does shine.
another advantage of solar power is that you don’t need a grid
Why not? You still have the same distribution issues as at present. Most countries which use a lot of power don’t get much sun, so local generation (the only way to avoid a grid) won’t work. For local generation to work, one would need battery storage and a roughly 2 orders of magnitude reduction in the energy needs of the average house, which is beyond any realistic technological vision.
In developing countries they can still make a lot of sense. In cool countries, heating accounts for most of your energy use, and the worse the weather the more you need. In hot countries you tend to need air conditioning the most when it is the sunniest so your power output tracks your power consumption better. If you have a washing machine, you run it when it’s sunny.
In rural Indonesia I’ve seen them used without a grid, in places where installing a grid would have been next to impossible. Every house in the village had its own solar panel and battery. You don’t need a lot of power to make a real difference to people – enough to run a few LED lamps is all it takes. A computer or TV are a bonus.
In the UK I agree – you would still want to be connected to a grid and you would need other sources of energy. At the same time, I think there would be some value in being able to keep the lights on for at least some of the time should the 1970s come round again. I have a colleague who thinks this way and is looking into buying a Tesla powerpack and a holiday home in rural Turkey which he believes will ride out any coming global catastrophe better than anywhere else. Quite why he believes that, or how he plans to get there when the catastrophe comes, I don’t know.
As for batteries: 17tWh is a lot, but not a ridiculous figure:
https://www.visualcapitalist.com/battery-megafactory-forecast-1-twh-capacity-2028/
I don’t believe that solar power will be the best way to meet all our energy needs, but it could do so.
Peter wrote:
What would you do about when the sun doesn’t shine?
Well, unless the sun dies and when it does it will take us all with it, it always shines. The question is intensity. Even during the biggest cloud cover we get daylight, so there is still quite some radiation coming through.
I see this on a quite small scale with my garden lamps which since several years are purely solar. They light up all year, all weather. The difference is that they often last till morning in summer but will fade out in bad weather after a few hours. Now these are £2 chinese rubbish lights from Jysk. If you use better equipment, you get much better results.
Just seeing how easy it is to produce warm water… the most primitive system is a black painted metal barrel on the roof. Friend of mine has a sophisticated system with panels and a boiler which stores the water and distributes it for a hotel with about 20 rooms. From April to November often enough he does not have to use any electricity to heat water and during the other months a fraction of what he’d have to use otherwise. We also changed all the lightbulbs in his hotel. The power bill he pais has gone down 80% and that is while he still cooks and uses TV and other equipment.
Even in the UK this should be worthwile. Silvaire has a point about the Grid. Houses which are self sufficient, heat their own water and produce electricity, sometimes even feeding back into the grid, are a good example of what is perfectly doable.
I have always been fascinated with PV since I was a kid when the first cells came out and would love to go self sufficient. I also have the ability to use a huge south facing roof on a storage warehouse which is located 250 metres away from my house.
I read in the Economist (like the other publications, they have lost balance Global Warming since the new Editor took over) that all sorts of exciting technologies are on the way where multilayered cells can capture the IR/ heat component in the suns rays to get efficiency up to 30%. I will certainly be interested when the time comes, perhaps using them to drive a ground source heat pump.
I looked at thermal water systems, but in the UK, they freeze in the winter, can boil in the summer if not used.- so when you are away flying on a hot summers day you will return to a plumbing disaster on your return. The payback is awful and the few I saw installed where I live have been ripped out over the last 20 years. The problem is, when something is only generating say £ 120 – £ 180 of hot water per annum and it breaks down, a plumber will charge a minimum of £ 100 labour and what ever the circulation pump costs. I nearly made a 100% home built unit which would have had payback if I kept the materials costs to £ 350 and ignored the value of my labour. They work really well in the Med but not in the UK.
So I agree with Bjorn Lomborg, when (a) PV efficiency is higher to make up for the miserable UK sunshine and (b) it is economically viable, then I’ll jump in.
I don’t like Governments picking winners as they almost always get it wrong. Subsidies for Diesel cars in the UK for example – that worked well! However if I was in Government I would offer a prizes of £ millions (perhaps hundreds of millions) to anybody who could achieve PV efficiencies in 2% increments – so 24%/ 26%/ 28% etc. In return for the prize the Government could take a 10% share in the Intellectual Property rights.
Just imagine of we could have PV’s with 50% efficiency. Suddenly things would change
I’ve just done a quick test of a photovoltaic (PV) panel, about 30 × 60cm, open circuit voltage 20V in full sun. Output current:
Full sun 0.98A
Via thin cirrus 0.8A
Via some haze 0.5A
Via thicker haze 0.2A
Bright overcast day 0.05 to 0.1A
And these numbers are into a short circuit. So if you want the current at say 10V (which would be the best power transfer condition, in the full-sun scenario) you need to halve it i.e. 0.5A.
So you need to take marketing numbers with a huge amount of scepticism… because most of the time you will be getting somewhere south of bugger-all, having spent a few tens of k rebuilding your roof with it.
PV is OK for low power demands e.g. remotely located radio towers, data acquisition, electric fences for cattle/horses/sheep, and other things where the power requirement plus the power for recharging a battery can be met with overcast daylight only. There are many such applications. The panel I tested above will give you 50mA all day, at say 6V.
To charge an electric car, you would need a lot of roof area, and if you don’t have that, a lot of land, but land is wasted by covering it with panels. And somebody has to keep spraying weed killer under them, which is not great… But it won’t work at all unless the sun is properly shining (or you almost never drive the car).
Just imagine of we could have PV’s with 50% efficiency. Suddenly things would change
I don’t think so… the difference between 25% and 50% is just a little bit less cirrus cloud.
I looked at thermal water systems, but in the UK, they freeze in the winter, can boil in the summer if not used.- so when you are away flying on a hot summers day you will return to a plumbing disaster on your return. The payback is awful and the few I saw installed where I live have been ripped out over the last 20 years. The problem is, when something is only generating say £ 120 – £ 180 of hot water per annum and it breaks down, a plumber will charge a minimum of £ 100 labour and what ever the circulation pump costs. I nearly made a 100% home built unit which would have had payback if I kept the materials costs to £ 350 and ignored the value of my labour.
When I started in business in 1978 I used to manufacture differential temperature controllers for solar water heating. So I got to know quite a lot about that business. I posted about it here. Yes, the system just rotted and fell apart after some years. Eventually the vacuum tubes solved most of the rot issue because they could withstand the thermal situation which you got when the stored water was hot enough and you had to stop the circulating pump. But they are messy to install, need to have tiles under them, and you usually get leaks around the pipes, cables, etc. Roofs need to be seriously watertight, in Europe. Overlapping ceramic tiles deliver this and have done for thousands of years. As soon as you get away from those, you are facing serious issues with materials, corrosion, sealants, etc.
This stuff, and PV panels, really needs specially designed roof modules which completely replace the roof tiles, so you strip off the whole roof and replace it. This is going to cost way more than the basic cost of the panels.
But water heating will never be worth doing because of the cost versus the few-hundred a year gain. You never get a payback.
They work really well in the Med but not in the UK.
That’s because they don’t use a pump there. The tank is above the panel, and runs on convection. Dirt simple and cheap and nasty and when it falls apart you chuck it out and get another one.
They are pretty useless too; you don’t want to stay in a Greek hotel which heats its hot water with one of these 
We must all examine our carbon footprint!
LOP is the way forward
Please look at the attached chart for the emissions/intake of CO2 on the planet.
CO2 balance sheet
A rough estimate is that the human CO2 (antropogenic) accounts for 4% of all CO2 emitted.
CO2 is a harmless greenhouse gas, but only about 4% of the total, the majority being water vapour.
Antropogenic CO2 being 4% of 4% thus Antropogenic CO2 is 0.16% of GHG.
If the temperature of the planet goes up (think solar activity and other factors) then the atmosphere will hold more water vapour (96% of GHG) because of evaporation, and more weight of water held in the atmosphere.
On the other hand, if NO GHG would be present, the average temperature on the planet would drop by about 33°C. Life would only be possible at the equator and only just.
I am all for a better environment, less pollution, but the current CO2 mania is clearly driven by a different agenda.
If you want to know more, please read “The deliberate corruption of climate science” by Dr Tim Ball.
I knew @Peter would leap in on the thermal panels as I remember your previous posts about used car salesman etc
I’m primed and waiting to do my PV roof but Peter’s post has dashed my hopes a little. I love the idea of “free” power but before I do it I’ll send my calculations to Peter so he can do a discounted cash flow for me. The trouble it, if I leave it too long then I’ll also need to look up Actuarial tables on my life expectancy and factor in (a) I eat a largely plant based diet but (b) drink more than 2 units of alcohol a week.
I am with @dirkdj. My gut feeling is that if you have a negative feedback loop in electronics or all sorts of scenarios then you tend to have a stable situation. So logically why would releasing a small amount or stored solar energy (coal/oil etc) or CO2 in an earth which is billions of years old, + has been through warmer/colder/higher CO2 periods in the past stay stable for that long and then decide to suddenly fry the “Sinners” now.
Having said all of the above, I am not a denier but I want to see better reporting and balance than the rubbish I see from the “dumbed down” BBC/ Economist etc.
I would not touch this with a bargepole.
Think of how many British bodgers craftsmen worked on your house in the last 20 years and what % of them bodged the job. And now imagine that lot crawling over your roof and drilling holes for stuff, and bunging up the gaps with some “trade” silicone sealant.
The UK gets way too little sun to do anything useful with the electricity, in terms of domestic requirements, or injecting it back into the grid.
It makes sense to do this only if building a “green” house means you get a planning permission which you would not get otherwise. So you are spending say 100k extra to get the planning permission, which is perhaps not too bad, in some cases. Cynical? A lot of planning policy is.
Peter’s tests with a solar panel exactly mirror mine (a while back I picked up an 80W monocrystalline panel, I use it for charging Li-Po batteries away from the house, and I observed its output in various conditions).
Also the sunlight has to be at right angles to the panel to make rated power, so really between -2 and +2 hours of solar mid-day is when you’re going to be making near full power, the rest of the day is a bit disappointing. You can of course solve that with a sun tracker but then you go from a simple, virtually maintenance free installation to something with moving parts and needing much more frequent maintenance.
Wind on the other hand is much more viable in these parts. In the British Isles, there’s a symmetry that when it’s constantly windy it’s also the time of year where the power demand is highest.
A friend of mine in Madrid moved into a new build block of flats a few years ago, it has central solar water heating on the roof and it works very well in Madrid.
