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Solar Freaking bike parking

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Nominal Animal:

--- Quote from: nctnico on March 05, 2024, 08:37:10 pm ---According to consumer pricing from Platio, it looks like these modules should be around 80 euro each.

--- End quote ---
According to MAKING-CITY project at Groningen, each module generates "approximately" 53000/2544 ≃ 21 kWh/year.  Let's assume generously that they last twenty years, with efficiency dropping linearly to zero during that time due to scratches and so on.  It means that during their lifetime, each module generates (21×20/2) kWh = 210 kWh.  To pay back just the module cost, none of the infrastructure (like cutting the hole in the pavement/asphalt, digging the holes for the modules and wiring), electricity price would need to be 80/210 €/kWh ≃ 0.38€/kWh for even just the price of the modules to be covered by the electricity they provide.

Even if we correlate for the average sunshine hours between Madrid and Groningen, each module only generates 36 kWh/year in Madrid, corresponding to break-even electricity price of 0.22€/kWh.  Again, this only covers the price of the modules, not the installation; cutting into pavement/asphalt to embed the modules into will cost a lot.  Perhaps not as much as a bike shed or leanto, but at least 1k€ (amortized 33€ per module; cutting and digging into pavement/asphalt is slow and takes both manpower and tools), putting the cost-benefit calculation clearly into the negative.

(And we've not taken the price of the inverters or DC/DC converters and batteries or other infrastructure needed to use the electricity.  That stuff is expensive, especially if we count the full 20 year expected lifespan.)

As I said, it looks like waste of money to me.  At least a roof or lean-to would provide comfort during the few cold rainy days in December–February Madrid has, and shade during the many hot summer months and days.

SiliconWizard:
Yes, it's a waste of money. As you noted, you don't even count all associated costs, and assume a very generous 20 years, which that'll never reach in practice.
You need to understand that the money is not lost for everyone though.

Nominal Animal:

--- Quote from: SiliconWizard on March 05, 2024, 10:34:16 pm ---Yes, it's a waste of money. As you noted, you don't even count all associated costs, and assume a very generous 20 years, which that'll never reach in practice.
You need to understand that the money is not lost for everyone though.

--- End quote ---
Oh yes.  Entire taxpayer-funded careers will be based on this stuff, no doubt.  With kudos and accolades and opportunities to match.

Nothing new there, though.

nctnico:

--- Quote from: Nominal Animal on March 05, 2024, 10:30:56 pm ---
--- Quote from: nctnico on March 05, 2024, 08:37:10 pm ---According to consumer pricing from Platio, it looks like these modules should be around 80 euro each.

--- End quote ---
According to MAKING-CITY project at Groningen, each module generates "approximately" 53000/2544 ≃ 21 kWh/year.  Let's assume generously that they last twenty years, with efficiency dropping linearly to zero during that time due to scratches and so on.

--- End quote ---
You keep assuming that scratches make the power output drop to zero but this is a false assumption. For starters: dirty solar panels have a slightly reduced power output like in single digit percentages. Lots of lamps have frosted glass (with millions of scratches) but this doesn't prevent the light coming from the bulb from entering your room. Also keep in mind that human eyes can only see a fraction of the spectrum the sun is emitting so looks may be deceiving. Some materials which block visible light, are transparent to infrared (which is also converted into energy by solar cells).

BTW: 21kWh per tile (35cm x 35cm) per year is not bad at all but likely optimistic. A 400Wp panel tilted towards the sun at an optimal angle, will produce around 25kWh/year given the same surface area (going by data from the solar panels on my roof).

Nominal Animal:

--- Quote from: nctnico on March 05, 2024, 11:08:14 pm ---You keep assuming that scratches make the power output drop to zero but this is a false assumption.
--- End quote ---
The 2019 heavy bike traffic tests in Krommenie, Netherlands, failed within weeks.

The bike path one can expect four year functional lifetime, until the tiles get too broken up to be safe.  The front courtyard of the campus building in Madrid is likely heavier traffic area than the Dutch bike test path was.

Thus, the 20-year lifetime, and the estimated electricity yields (as given by the project promoters, which seem to be extremely optimistic wrt. confirmed results), are ridiculously overestimating the module lifetime output; as in by a factor of two to five.

If I recalculate the same using Madrid vs. Groningen average sunshine hours, five year lifetime with no degradation, at the projects own estimate of electricity output, it still puts the break-even electricity price point here at 80€ / (5×36 kWh) = 0.44 €/kWh.  That is the figure we have now, from existing tests.

To declare the installation worthwhile, you need to include the price of the inverters, converters, batteries, maintenance, and physical installation; and there is no way this could ever pay for itself.  We know from actual data that rooftop solar panels generate twice the electricity compared to ground-based panels at the same surface area, so even if electricity prices were to skyrocket, it'd just mean more panels on Madrid's roofs, not that the silly ground panels magically become profitable.

Simply put, because of the rooftop vs. ground production difference, ground-based panels just do not make any financial sense.

I am not claiming that a lean-to or bike shed with panels on the roof could pay for itself, either; but that at least those would provide comfort for both rainy and sunny days, and the rooftop panels offset their cost.  It is the roof that is useful for bike stops, moreso than the electricity.  Putting the panels on the ground is just throwing money away, because it is so much cheaper and more productive to put them on an existing roof.

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