Do solar panels really work during the winter?

Filed in Blog by on April 9, 2012 19 Comments
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Mr and Little Miss Green enjoying solar powered lighting during winter!

Mr and Little Miss Green enjoying solar powered lighting during winter!

I’ve mentioned solar power here on My Zero Waste before. While it doesn’t really come under the remit of ‘zero waste to landfill’, it certainly ticks all the boxes for a more sustainable lifestyle, and I know many of you are aware of the bigger, ‘green’ picture in your day to day lifestyle choices.

Here at Zero Waste Towers we have two small solar panels that we use to run the downstairs lighting. Mr Green has built some high spec LED light bulbs as these are several times more energy efficient than CFLs. When you’re generating your own electricity every watt counts!

While this winter wasn’t exactly harsh, I don’t know about you, but I noticed just how DARK it was. I use a SAD light box and I really needed it this year. It seemed that the skies were grey a lot of the time and the light didn’t really get through the clouds.

Our solar panels are photovoltaic and, during the daylight hours, they charge a 12 volt battery system made up of leisure batteries. These in turn provide low voltage energy to power all of our LED lighting.

If you read about solar panels you’ll be told that they work even on cloudy days, which is true, and, whatsmore – and somewhat ironically – they are more efficient when they are cold.

Cloud and snow

However, unless they are at that mysteriously perfect angle to the sun that seems to require the brains of a professor to figure out (and of course changes throughout the year), then the light-to-electricity conversion is less than optimum. This means that in the winter months, when the sun is lower in the sky, there is less electricity generated. In addition, less daylight hours and more likelihood of cloudy conditions further reduces the amount of electricity generated. So, on a cloudy winter’s day, the amount of electricity generated can be reduced by as much as 75 per cent compared to a summer’s day of full sunshine.

This power reduction during wintertime is very significant because it’s during the darker days and longer nights that we demand more electricity, especially for lighting. Another wintertime issue is that solar panels, depending on the pitch of the roof, can become buried under snow, so their light to electricity conversion drops to zero.

An investment for the future

The way to win is to have an excess of solar panels in order to compensate for the significant loss of conversion during the winter months and cloudy days, but then you need to take the cost into consideration. I appreciate the companies that are honest about this. For example, MyRedlandRoof, who advocate solar power roofs point out that the chief disadvantage of solar panels is the initial cost of installation. However, the cost of producing solar energy appliances is falling as technology develops and, as the cost of fossil fuels continues to rise steeply, solar energy becomes an increasingly attractive option.

Night Lights

Many people who have solar don’t run low voltage fittings such as ours: they feed the power from the solar panels into a mains inverter, then any electricity not used gets fed back to the grid for the householder (or solar company if it’s a free installation) to benefit from the Feed In Tariff. For most people solar energy is only advantageous during the day because there is no battery backup or store, making them reliant on utility providers at night-time.

What I love most about our setup is that even during a night-time power cut we can still run the lights! The bottom line is that, yes, solar panels DO work during the winter months but they are much less efficient. In an ideal world I’d have other sources of sustainable energy to use as well, such as a small wind turbine to generate electricity, geothermal for heating and biomass for hot water.

What about you – do you use any renewable energy sources at home? I’d love to hear about your experiences as we are still pretty new to all of this!

About the Author ()

I am a long time supporter of the Green and Sustainable lifestyle. After being caught in the Boscastle floods in 2004, our family begun a journey to respect and promote the importance of Earth's fragile ecosystem, that focussed on reducing waste. Inspired by the beauty and resourcefulness of this wonderful planet, I have published numerous magazine articles on green issues and the author of four books.

Comments (19)

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  1. Carrie says:

    Hi there Mrs G. Another great post! We are currently trying to save our pennies in order to go “off-grid”. Not an easy challenge.

    We live in the middle of a city, with little outdoor space, so the only viable option seems to be an Air Source Heat Pump, which is a bit like a backwards fridge (or so I’m told). Converting heat energy out of the air, and working up to -5 degrees C. But the cost will be around £12k and as it still uses electricity to power it, the last I heard, government won’t give it a grant (although, frustratingly, they do on Ground Source Heat Pumps).

    We are also looking at Solar Panels. We costed them at about £7k, as the prices have tumbled lately. But we have a line of council owned, very large, trees bordering our property and would need to get them topped and thinned first and the council are being their usual unresponsive-selves… sigh.

    I love your wood burning stove, and I recently found a company here in Edinburgh, that fits them to a smoke-free standard, meaning we could use them in the city. Which is another option for us to consider, although I haven’t priced them as yet.

    In the meantime, we shall have to keep saving! Ironically my gas heating is bust at the moment, so I am being very green with no heating at all! (although it is a tad chilly!)

  2. I loved this post. You inspire me so much.

  3. glaw5 says:

    Really interesting post.

    Carrie would be interested to know the company you’ve found in Edinburgh. I’m in Glasgow but would be handy to have a starting point as thinking of installing a woodburner too. Thanks a lot.

  4. Mrs Green says:

    @Carrie: You’ve got some great plans Carrie; I hope you manage to manifest them all and good luck with everything …

  5. [email protected] says:

    Well solar panels are not efficient and only convert about 22% of the available energy into electrical energy. This is around half that of a coal power station/ In fact all renewable energy sources be tidal, solar, hydro, or wind have efficiencies between 10-20% and so it is a lot of effort for very little return. The jury is out at the moment to their suitability for the countries needs and you need a house to be south facing. You can never power a house totally in the Uk by solar power (not enough hours of sunlight)but you must have the national grid as a back up. The biggest draw back is that you cannot store electricity (unless you want a bank of huge rechargable batteries in your backyard) and it must be used as it is produced.

    When you said that “Our solar panels are photovoltaic ” i had to fall out of my chair laughing as you know that photovoltaic is the technical definition of solar power see http://en.wikipedia.org/wiki/Photovoltaics. You are really showing you lack of technical ability.

    The best way to cost a project is to use a technique called the Net Present Value (NPV) calculation as this not only takes in capital cost but also operating cost, labour cost, taxation, inflation, tax levies, interest payments, maintenance cost and all other costs in the calculation. What project has the highest NPV (or lowest negative NPV – meaning that you will never make money over the whole life of the equipment) will be the most favourable. Decisions should never be based solely on capital cost because overall it may cost you more as the other costs may be higher.

  6. Nick Palmer says:

    [email protected] wrote:

    “When you said that “Our solar panels are photovoltaic ” i had to fall out of my chair laughing as you know that photovoltaic is the technical definition of solar power see http://en.wikipedia.org/wiki/Photovoltaics. You are really showing you lack of technical ability”

    You leave our Mrs Green alone. Your post is full of misleading rhetoric, inappropriate comparisons and the nitpicking focusing on words taken out of context that is typical of so much denialism these days.

    It is no surprise that the two sentences of yours I quoted show clearly that you don’t really know what you are talking about. “Solar panels” as a description can either refer to photovoltaic or thermal panels so your ill mannered sniping was just plain wrong. Apologise.

  7. [email protected] says:

    @Nick Palmer: Apologise for speaking the truth! Never. I am simply stating facts and if you don’t like it then it is tough luck.

  8. Nick Palmer says:

    @[email protected]:

    You were stated cherry picked facts mostly in a way that was highly misleading, therefore you were not “speaking the truth” at all. The specific point I made about the incorrectness of your sneers at Mrs Green:

    “i had to fall out of my chair laughing… You are really showing you lack of technical ability”

    stands – you either didn’t properly understand what she wrote or you are just another one of the drive by denialists seizing on cherry picked phrases to mislead the audience.
    —————————————–
    Mrs Green. In my experience fighting climate change denialism online I have encountered hundreds of commenters like apachowko. Often I have found their main problem is they cannot properly understand when someone points out their errors or misunderstandings. Strangely, they seem unaware that their comprehension is not all it should be yet they have a misplaced confidence, often arrogance; a self belief that makes them act as if they are invulnerable. They rarely admit error but if you don’t stop this comment thread, and if apachowko is one of those, their incorrigibility will lead to their wrecking this post

    p.s. apachowko – re: “Apologise for speaking the truth! Never” the bit you clearly could not understand is that you should have apologised to Mrs Green for being not only wrong about the meaning you took from her phrase “solar panels” but also that you were being exceptionally arrogant and rude about what you thought it meant about her. Within the context of a blog post for the general public, Mrs Green’s explanation of some of the limitations of PV panels was clear and accurate information.

  9. Nick Palmer says:

    @Nick Palmer:

    Sorry – yYou were stated cherry picked facts ” should have read “you were stating cherry picked facts”

  10. [email protected] says:

    @Nick Palmer: You call someone you don’t know as arrogant and rude, whilst defending someone who can clearly defend themself. This is not only presumptuous but you are in great error as you don’t know me. I am many things but I speak my mind as I believe in calling a spade a spade. From one little paragraph you made so many assumptions and yet you fall on your face as nothing you say is true. In fact I strongly believe in climate change but my point was the limitation that solar panels and other technologies have along with their reliability. In fact energy consumption will involve a mixture of nuclear, renewables, coal (using clean technology) and probably future technologies that engineers will develop. In fact I believe at the present moment CHPs (combined heat and Power Plants) will come increasely into play as many industries are doing so. For those who are unfamilar CHP produce heat (normally in the form of steam) and electricity at the same time. The technology is being miniaturised at eventually a portable unit will be generated that can be used in homes . The good thing abour CHPs is that any fuel can be used ( I admit most industries use natural gas or LPG at the Moment) from biomass to other fuels. I think coal gasification will be a force in the future as in is duel purpose it could be used to produce syngas and a starting block for organic chemicals (the reaction of carbon monoxide with water produces methanol), and secondly it could be used to produce heat and power-enough for many homes. Why coal? The answer is simple because we have such a large reserve in the UK (around 400 years if abandoned mines can be reclaimed because once a mine is flooded it is inoperable).

    Coal gasification is such a promising technology and it surprises me that in the UK it has not really taken off. For those who are unfamilar with the technology it involves reacting (burning) a fuel such as coal, but any organic material can be used such as wood waste, with a reducing atmosphere- air with a reduced amount of oxygen to form a synthetic gas, a gas which is rich in carbon monoxide and hydrogen. The reaction takes place at high temperature and pressures where the syngas that is produced is cleaned (particulates removed) and passed through a gas turbine , where electricity is generated. The waste gas is then combusted and passed through a waste heat boiler where superheated steam is generated. The steam passes through a steam turbine, where more electricity is generated. Part of the steam is diverted and used for heating purpose. As a home is not a chemical complex then the process of reactor, gas cleaning process, WHB, turbines can be minaturised. It could be used instead of a wood burner but the technology is still developing. The ash that remains will be still a problem amd it has limited uses.
    Thermodynamically speaking this will be more efficient than most other technologies.

    You call my arrogant and rude and i don’t particular care what you call me. Your opinion doesn’t matter to me and your misguided attacks on me whilst defending Mrs G smells of double standards.

  11. [email protected] says:

    @Nick Palmer: bTW it is called levity something a person with no sense of humour knows nothing about.

  12. Nick Palmer says:

    apachowko.

    You mention a lot of other technologies in your reply but all of your blustering does nothing to change the facts, as anyone can see by looking at the original posts above.

    In a post headlined “Do solar panels really work during the winter,” Mrs Green wrote this line:

    “Our solar panels are photovoltaic and, during the daylight hours, they charge a 12 volt battery system made up of leisure batteries”

    When solar panels are mentioned in the media most people will tend to think of a panel that uses the Sun to heat water. Mrs Green simply clarified which type of panel she was talking about and you jumped on this to “fall out of (your) chair laughing” and even gave a Wikipedia reference to try and prove something based on your fallacious understanding.

    You seem to be a big fan of coal gasification yet you also claim to “strongly believe in climate change”. This is strange. Combusting the syngas from coal gasification is still inescapably putting fossil CO2 into the atmosphere. Carbon capture and storage technologies are far less mature than Solar PV.

    Your initial post bizarrely suggested that because solar PV panels were “less efficient” than coal plant that somehow they were not worth using. Firstly, it ignores that any coal plant pours out CO2 – more carbon per unit of energy than any other – which is not helpful to avoid climate change. Secondly this idea that only the most “efficient” system is worth it is just garbage! Photosynthesis is a very “inefficient” process but it feeds the world and everything in it. Using your strange “logic”, we should replace all the trees and crops with coal gasifiers, converting the syngas “efficiently” into nutritious products. Crazy, huh?

    You then went on to claim that:

    In fact all renewable energy sources be tidal, solar, hydro, or wind have efficiencies between 10-20% and so it is a lot of effort for very little return

    which is just highly misleading scientific gobbledegook.

    Sure, Mrs Green can defend herself but I’m not defending her, I’m attacking you. I am doing this so that all the onlookers who read these comments can see your ill thought out and inconsistent views answered.

  13. Nick Palmer says:

    Oh, BTW, that was my last word on the subject here.

  14. [email protected] says:

    @Nick Palmer: Yet again Nick has shown how intolerant and ignorant he is. He uses a lot of posturing to demonstrate his claims without nothing to back him up. Empty words from an empty person, using words to cover up his inadequacies and lack of ‘real’ knowledge. His claims are not only ludicrous they are not based on the real world.

    His first point is mute. As a I am not suggesting a standard coal power station but a Coal gasification Combined heat and power plants that will have an efficiency of 60%. Higher efficiencies would mean less fuel and as a result would mean a REDUCTION in carbon emissions. A 60% efficient gasification power plant will have 40% cut in carbon dioxide formation compared to the traditional coal power plants. So Implementating and Replacing Coal power station with gasification plants will reduce carbon emissions. A fact he clearly ignores.

    Did I ever say I am against solar panels? No I am just pointing out compared to traditional technology they are less efficient and reliable. You can never supply 100% of the UK electrical Energy needs by solar panels. It is unfeasible and costly. They have uses and should be used where possible but it will not solve the greenhouse gases issue or future energy demands that need to be met. The impact will be small but every % reduction will be useful. I said so that renewables will be part of the mix but he ignores it .

    The second argument ” most “efficient” system is worth it is just garbage! Photosynthesis is a very “inefficient” process but it feeds the world and everything in it” is such a misleading statement. Photosynthesis is a natural process and all forms of electrical energy production involves man intervention to produce it. It is like comparing apples and oranges.. It is pure nonsense. It is a diversion tactic to avoid the real issue. The two processes will exist in synergy. You are wrong Efficiency is very important as low efficiency means that more units are required to do the same job, Making it costly or that the running costs will be higher. If efficiency was not important then engineers will not be trying to make machines run any better or try to improve processes. It will be a waste of time. The argument does not hold and compare it to a natural process in which no one has any influence over is crass.

    Back to gasification process he avoided that I said that other fuels could be used such as biomass and even waste. This includes household, commercial organic waste which would be diverted from landfill. It looks like that Nick want the household and commercial waste to go to landfill increasing methane production.

    He also missed that I said Coal gasification can be used to produce the starting chemical for which modern society depends on. Does Nick want to depend on crude oil or does he know it is running out? The other advantage is the hydrogen used could be used in fuel cells to power vehicles. As 25% of carbon dioxide emission is from cars (industrial CO2 emissions have been decreasing steadily over a number of years) could you imagine the reduction of vehicular carbon emission because of gasification. The sulphur recovered from the coal could be used to make sulphuric acid, the number 1 most used chemical in the world via the contact process.

    In effect gasification would be more efficient, producing less CO2, producing chemical that society depends on, reducing landfill and possible car emissions.

    He has not made one thing to back up his statements (which are easy to made) and I am sure that onlookers would see the ranting and raving of an incoherent individual.

  15. Teresa says:

    I’m seeing more and more solar panels on the roofs of buildings where I live. Install them if you want but install them for the right reasons which is to use less electricity from the grid not top it up with solar panel energy as many solar panel users are doing. They turn up the heating at home and buy more electrical gadgets to use. Large flat screen televisions, digi boxes, lap top computers and Pac Mans. Television on all the time in the living room. They buy a Kindle which needs recharging and don’t bother with books anymore. They don’t write on paper anymore but note things down in their i-Phones which need recharging regularly. I dare them to monitor their electricity usage before and after installing solar panels.

    • Fajyna says:

      This is old but…. pretty sure a kindle is better than all the paper to make those books abd then the power needed for lights so that you can read at night.

  16. Gerald Brady says:

    I have just been something that says solar panels can be running at only 50% when the weather is cloudy. This is complete tosh. On cloudy winter days my panels produce almost nothing and on one day last winter, exactly nothing. I am still very happy with my panels and I would recommend them to anyone but it doesn’t do anyone any favours by pretending that they work well under cloudy conditions. I have a 3.84kw system which produces around 3,500kw per annum (which is more than I have to buy from the grid)

  17. Gerald Brady says:

    Oops….I have just re-read my post and it sounds rather snotty. I apologise for that. The worst performing day for my panels this year was the first of January when they generated 0.2kw and the best was on the 16th of March when they generated 22.4kw.

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