Those of you who know me better, know also, that I am a moderate fan of photovoltaic energy systems (solar panels). The first solar panel I bought (flexible 10 W) 5 years ago, and since that time, my PV system has grown to 150 Wp. Lately I aquired two 30 Wp panels, which I want to review here as soon as possible.

I calculated some time ago that photovoltaics is not a viable solution from the economic point of view. But is it worth to spend energy od manufacturing PV panels and use them somewhere else to produce solar power? Isn’t it just a way to store electrical energy? What is the EROEI of such an investment?

I wouldn’t worry about that if I didn’t hear an interview with Steve Harris of, who is an expert in the energy field. He said that PV systems are one of the worst investments you can make, because you simply transfer energy in the form of silicon crystals from Japan to USA or Europe.

Energetic cost of manufacturing solar cells

I found this article written 5 years ago (referring to some studies made in 2000), where the energy cost of manufacturing 1 m² of mono-crystalline solar silicon is calculated at 6,900 MJ, equivallent to about 1,920 kWh (which includes photovoltaic cells, the solar panel case, frame assembly, control electronics, etc.). With the assumed efficiency of 13%, the power generated from 1 m² of solar panels will be equal to 130 Wp. Such solar panel in Polish conditions can produce 117 kWh per year (assuming the losses of the entire photovoltaic system losses are equivallent 14%).

So how long will it take to get a return on such an investment?

A simple payback time in those conditions is roughly 16 years. Since the article refers to research conducted in 2000, this time probably is shorter today as the energy cost probably is a bit smaller. But still that does not take into account the cost (energy) to ship these solar panels to Europe.

Nevertheless, my moderate enthusiasm for solar power and photovoltaics didn’t go away. I will still try to invest wisely in the solar panels, whenever I see a good oportunity.