How Efficient Is Solar Energy

The efficiency rating of solar panels is fairly low i.e. the amount of the suns energy converted into electricity. Depending on your situation it can range from 5% to 15%, although there have been some recent breakthroughs in technology which has increased this to 40%. However it will be some years before this technology becomes commercial available in the solar panels we fit to our homes.

When calculating how many solar panels you need for your home, you don’t need to be too concerned about the efficiency rating of your panel because photovoltaic solar panels are specified by their energy generating capacity. For example, 100 watt panels will output 100 watts of energy under ideal conditions. So if you are looking to produce 1kw per hr of energy you will need 10 x 100 watt panels.

Solar panels range in their energy output. Typically they range from 30 to 205 watts. If you are DIY then pay special interest in calculating your energy requirements. If you are getting a company to draw up plans for you then they will take care of this calculation.

There are three main types of solar photovoltaic cells and these are polycrystalline, monocrystalline and thin film. Each has different efficiency ratings when converting the suns energy into electricity and they all have their pro’s and con’s.

The main difference between them is size and price. The more efficient technologies like monocrystalline panels are more efficient than the other two and so the panels are smaller and take up less space when comparing like for like in energy output but they are more expensive.

So before you decide which panels to go for, you need to calculate your energy requirements, establish how much you want to invest and then go and compare the different panels.

There are many other aspects that can affect the efficiency of your panels. We find the following to be the most common: how often you clean them, are they infrared, how much sun do they get and how hot do they get. It is a surprise to many people that for most panels their efficiency drops when the temperature starts to go above 25 Deg Celsius.

Keep in mind, in this article we have been talking about photovoltaic electrical solar power generation. If you want a hot water heater conversion then solar thermal panels are a lot more efficient.

In summary, on face value solar energy does not seem very efficient, although it is improving year on year. However, don’t get too tied up about the efficiency of the panels, focus more on the output, size and level of investment.

If you have any efficiency figures of your own which you would like to share with us then please feel free to add them to this article by adding a comment below.


16 Comments on How Efficient Is Solar Energy

  1. Vanessa E. on Thu, 16th Apr 2009 1:24 pm
  2. How much does it cost to apply solar pannels. Is it very expensive to have your own solar energy setup if you do it yourself?

  3. Simon on Thu, 16th Apr 2009 1:33 pm
  4. You can buy kits which come in different sizes. For example, a grid tied kit which can output up to 1KW is about $8000 and a 2kw solar power photovoltaic system would cost about $12,000. Alternative you can build a solar panel which will save you money, but obviously it takes up your time to build the actual panel.

  5. ainsley on Mon, 18th May 2009 5:19 pm
  6. does solar energy systems produce more energy then it wastes?? if so what does it waste??

  7. Simon on Thu, 21st May 2009 6:57 am
  8. Solar energy systems are not that efficient, if you can convert 15% of the sun’s energy then you are doing quite well. However, this is a lot more efficient than they use to be and the way technology is moving hopefully this will shoot up to 50% within the foreseeable future.

  9. Shannon southall on Sat, 14th Nov 2009 4:52 am
  10. does solar power effect the environment? how much green house gases does it produce?

  11. Simon on Wed, 18th Nov 2009 3:55 pm
  12. Solar power doesn’t affect the environment directly or should I say that when manufacturing the solar panels, the manufacturing process uses fossil fuels also putting the solar panels on your home or having a bank of solar panels will have a small impact on asthetics but then again many people like the look of solar panels.

  13. RB on Tue, 30th Nov 2010 5:30 pm
  14. Does any one know what the percentage degradation on Typical Solar Panel …
    ie: After 10 years do they lose 25 % efficiency ? more than that ?
    After 5 years ?
    I know it probably depends on weather conditions – I’m in Canada where there is a pretty severe freeze and thaw cylce and extreme temperature variation. ie: -35 degrees C in winter and close to +40 degree celsius in Summer.

  15. ryon on Fri, 3rd Dec 2010 8:31 pm
  16. So if a 100W panel will really only generate 10%-20% (10-20W) that is a major gap of energy that is not being produced. Thats 50, 100W panels @ 20% efficiency to get 1K system. Help me out with this please. I am confused.

  17. carmen on Thu, 16th Dec 2010 8:02 am
  18. hi, It might be little expensive but if you think for long run then it’s really worth,

  19. Simon on Wed, 29th Dec 2010 11:07 am
  20. You Guy are Such Geeeks And I Got A Question For You ;
    On a scale of 1 to 10 how efficient is solar energy?
    Thanks Geeks 😀

  21. AZMI on Wed, 23rd Feb 2011 7:10 am
  22. Hi, in terms of electric power, how many of our electrical appliances do the solar power support the usage? I mean, how long and how many of them can be operated simultaneously?

  23. David606 on Tue, 31st May 2011 3:52 pm
  24. If you operate a 2 kW grid-connected solar collection system, you can operate a hair dryer, microwave oven, or refrigerator, but not an electric range or electric hot water heater. Does that help? If you heat or cool your home with electricity, the 2 kW will not be enough to do that either. If you have a home of, say, 2,000 sq ft, you probably use 2 to 3 kW average. My annual average use is 2.9 kW, but my peak use is about 15 kW. But no matter what your average use, the sun only shines sometimes, so you need an energy storage system (batteries) or you need to buy nighttime energy from your utility. And if you store energy in batteries, they cost a lot. Given the cost of everything, I’d be willing to spend $25K if I could get a 15kW system. I’d want to be able to store one day’s worth of charge in batteries, which would be about 15 kW x 8 hrs = 120 kWhr. A standard car battery of 80 ahr holds 12 v x 80 hr = 960 Whr, so we’d need about 125 of such batteries. At $50 each, that’s over $6K just for batteries. Then there is the cost of cables and a storage area. Unless you are a survivalist, forget the batteries and sell the excess to the utility. For emergency power, I would recommend buying a generator. A good 3kW generator is about $3K.

  25. Nima on Tue, 7th Jun 2011 10:49 am
  26. Hi, can you help me to know how much it cost to generate enough electricity for an airconditioner , refregerator & two televisions.
    I live in south IRAQ ,I am willing to use solar energy so as many people here .
    We have alot of sun & we are looking for an alternative source than the usual electricity

  27. Ethan on Thu, 10th Nov 2011 1:09 am
  28. How efficient is solar energy on a scale from one to 10?
    Thanks! 🙂

  29. Dave202 on Thu, 29th Dec 2011 12:52 pm
  30. Nima

    I suspect that in Iraq your sun levels will be good, and your day length will typically be around 11-12 hours. Your refrigerator in Iraq might need relatively a lot of power, maybe 2-300 watts. In colder countries an efficient fridge should take less. Small LCD TVs operate at about 25 Watts, larger ones (42 inch) about 150 Watts. Plasma TVs are about double that. Your air conditioner is likely to be your most energy intensive device, and it will depend on the size of your installation, the efficiency of the system, and how cool you like it how much power that uses. Without knowing more I’d say that could be anything between 1 kW and 10 kWatts.

    Your best bet is to find out the power for your air conditioning, then add another 1 kWatt for the TVs etc.

    A 16 panel system should generate around 4 kWatts. In the UK that might cost about £12000 ($20000 approx), and you’d need about 20 square metres of roof to put it on. You’d also need to find a way of connecting to your national grid, unless you use batteries and are completely separate from the grid. There are problems with using batteries for storage unless you really know what you are doing.

    There may be ways of connecting your panels to devices which are different in your country, but in most countries with a power distribution system the devices are designed to run at standard voltages using AC power, which is provided by an inverter from the solar panels. It is possible to use DC, but it can be dangerous. It can be difficult to switch high power DC, which might be particularly important in emergency situations when it needs to be turned off. Non standard devices might work over a wider range of voltages, and some might be capable of running off DC. Take advice from qualified engineers in your area.

  31. jeffrey on Tue, 6th Mar 2012 4:36 am
  32. Hi there, I just wanna ask on how solar electricity creates massive financial benefits to its consumers?

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