The most efficient solar panel?

  • #17210 Reply


    Had a company claiming they were one of, if not THE, most efficient solar panel. Producing 3.975kWh.

    Another claimed efficiency of 19.26% whereas the Solar World has only 15.5% – not sure how this pans out over time, but one of the lads on here might explain?

  • #17211 Reply

    Pine Martin 66

    Hello BettyS. I expect some of the more technical people on here could give chapter and verse but my non techie understanding is that cell or module efficiency really has to do with the amount of energy generated per square metre, so the more efficient the panel the fewer of them you need on your roof. If you have a sufficient size roof to get 16 lower efficiency panels then you could get away with the Solar World ones.

  • #17214 Reply

    Norman Scottish Installer

    Efficiency governs the size of a panel not its output.

    i.e. A 20% efficient panel will be smaller in size than a 16% efficient panel. It needs less silicone per sqm to generate the same amount of power.

    When space is limited we like LG 300 watt panels.
    These are 1640mm by 1000mm which is more or less then same area than a standard 250 watt panel.

    However, because their efficiency is 18.30% they are capable of generating that extra 50 watts over the same area of panel. The module’s nominal power is interesting, as is its efficiency. But the single most important factor for PV panel operators is yield: how many kilowatt-hours per kW of installed power flow from the PV system to the inverter?

    Another aspect of efficiency is temperature. Contrary to popular belief, panels don’t work more efficiently in hotter conditions.

    Estimated losses due to temperature and low irradiance: 6.9% (using local ambient temperature)
    Estimated loss due to angular reflectance effects: 3.2%
    Other losses (cables, inverter etc.): 14.0%
    Combined PV system losses: 22.5%

    Hot panels can mean a drop in efficiency. If your panels can’t be seen from the road or if the look is not of prime importance to you then you might want to avoid the all black look which can heat up more.

  • #17217 Reply


    Additional information on the subject of efficiency by Norman.

    Photon Labs are a German organisation that tests and rates solar panels on behalf of manufacturers. The results are published quarterly.

    This is called Third Party Testing and is important as it verifies the manufacturers claims. Photon Labs are probably the leading 3rd Party Testing Organisation.

    This is a direct quote from their home page on the subject of panel efficiency:

    “A module’s nominal power is interesting, as is its efficiency – and, depending on the customer’s expertise, so are a few other pieces of technical module data. But the single most important factor for PV system operators is yield: how many kilowatt-hours per kW of installed power flow from the PV system to the inverter?”

    Efficiency will govern the size of a panel rather than its output.

    i.e. The LG 300 watt panel is 18.60% efficient and the Solarworld 250 watt panel is 15.10% yet they are more or less the same size. Because of its efficiency it needs less surface area to generate the extra power.


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