Solar PV system (part II)

An update to my last post which detailed our choice of solar PV system.

General details:

  • Size: 4.98kw
  • Type: Solar Frontier CIS panels
  • Panels: 30 x 165 watts
  • Direction: SSE

Potential return: approx. ¥30,000 per month

This is based on: average sunlight hours per day 5.6 hours, system size 4.98kw, conservative efficiency reduction 15%, rebate rates 42yen per kw hour)


About ifd66

From UK and living in Japan. I am very interested in sustainable development and in general ecology and conservation issues and solutions. Finished building a low impact family house in Shiga, Japan in 2013 and am now focused on using permaculture to develop our plot of land into a more sustainable, productive, and attractive space. My hope is that this blog is useful to those interested in similar issues and way of life.
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2 Responses to Solar PV system (part II)

  1. Paul says:


    How long do you think it will take for these wee babies to start paying for themselves?
    We have juggled with the idea of installing panels to our place (southern prospect, all day sun), but due to the cost involved think that it is cheaper for us to just live without them. It would take about 15+ years for us to see any profit in the outlay, by which time the panels may well need replacing, further setting us back. Over a year, our average monthly electricity bill is about 6,000yen.

    Questions that I asked myself were, how long does a computer last, 5-8years? How long does a fridge of washer last, 10 -15 years? How long will panels last? Will we really see any return on the investment? Do we want to wait 15years to see any profit by which time the panels could well be needing to be replaced. There will also most likely be continually cheaper options on the market over the next few years.
    What I would find interesting Iain is knowing what in the end sold you on the idea of getting panels? Other friends further down the lake have recently installed them. They also have a 5kw system.


  2. ifd66 says:

    How I see it when you buy a fridge, you get an item that keeps food cool etc, and when you buy solar PV you are buying an item that gives you renewable energy. But how many things that we buy, do we ‘expect’ to pay for themselves, and indeed give a return?
    That aside, at a cost of 1.36m yen, if we minimise the electricity we use during the day, thereby maximising the electricity we are selling back to the grid, we could get back most of the 30,000yen in potential tarrifs – a 360,000en return per year on 1.36m yen is pretty good – and even if you half the return its still greater than 10%.
    One other point, the panels in Europe and maybe the US too are generally guaranteed for 20~25 years. In Japan they seem to be tight and only guarantee for 10 years – but the same systems.


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