I'm interested in knowing the typical energy pay-back time of a solar photovoltaic panel, in terms of hours operating under an ideal scenario.

Energy pay-back time (EPBT) is usually quoted in terms of years, and often discussed in the context of permanent installations like power stations or rooftop solar. These discussions often include factors like average annual insolation. However, I'm interested in evaluating solar PV devices at the personal scale and might be used while backpacking, canoeing, or other wilderness adventure, where average annual insolation isn't really relevant because the device isn't used every day, and isn't used evenly throughout the year.

  • For static installations, we get payback time by using the price of energy from other available sources. The alternative source for a portable solar panels should be batteries, because there is not available wall plug, and since batteries are way more expensive payback time could be very short.
    – Pere
    Jun 9, 2019 at 11:17
  • @Pere My question is about payback of energy, not currency.
    – Nic
    Jun 9, 2019 at 16:10

1 Answer 1


Given that static, thin-film photovoltaic panels, exposed to the sun all day every day, might pay themselves off in 3 years (according to NREL in 2004), there is an extremely high probability that a portable solar panel — used relatively infrequently and under sub-optimal conditions — would never pay for itself.

If it takes (3*365=) ~1100 days at full exposure, or ~4400 days at sub-optimal/quarter exposure, you'd need to spend every single weekend 'adventuring' for (4400/2/52=) ~42 years before you reach payback.

Portable solar power generation has always been about convenience, not payback.

Update: Fraunhofer (in 2018) revised EPBT in northern Europe to 2.5 years, and southern Europe to 1.5 years. If we split the difference, and call it 2 years, you're still looking at having to adventure every weekend for 28 years before the panels break even. About (365*2=) 730 full-exposure days (~8,800 hours) are what you currently need in mid-latitude-Europe/USA. No doubt that figure will continue to reduce slowly over time, but it is still substantial and will remain so for a very long time.

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