Until recently solar panels were expensive and not efficient. Almost all buildings were built before you could recoup the cost of the solar panels. And even now it is a gamble as energy prices changes and the solar panels might get damaged. In some areas you might expect to recover the cost of the solar panels in ten years, in others never. And even if you should expect to get the money back for the investment you still need the money to buy and install the panels which not everyone have.
Because someone has to pay for it to happen. The time to payback is 5 to 15 years with is too long for a lot of people. Also the payback period depends on how the price of electricity develops which adds uncertainty.
Aguably rooftops are not exactly the optimal place to put solar panels either. It costs 2 to 3 times the price to place them there as opposed to many more at once in an empty field.
The feeling of grud independence is rather nice though.
It’s expensive and it’s not that solar panels can just supply the building they are on with permanent power. When there’s no sun you need to draw power from the grid and when there’s a lot of sun all solar panels combined feed too much power to the grid, overloading it. The only way that having solar panels on all buildings can be sustainable is if we can reliably store the excess energy for when it’s needed (plus a robust infrastructure that can transport those peaks). Home batteries can do some of that balancing but overall are still too expensive and have insufficient capacity to efficiently store the excess. What we should have is some type of huge communal storage that can fill up on sunny days and that the grid can draw from on overcast days.
I like the idea of solar panels.
But we live in an apartment building.
I cannot grab the space on the roof for my personal use. It is a common space for all residents of the building.
We could all get together for installing the panels but solar panels which can fulfill the requirements of an entire building would need a lot more space than is available on our rooftop.
We could install them to run our common amenities I guess, like the lights in the lobbies or in the parking spaces etc.
But then people won’t be able to go for a stroll on the terrace or to sit in the sun. Because the panels would occupy the space.
The cost benefit analysis depends on a whole bunch of things. Your latitude, your local climate, for how much of the day a tree might be shading the solar panels, both now and as the tree grows in the future, what direction your roof faces, energy prices, how the laws and contracts regarding selling power back to the utility company works, how closely peak usage aligns with solar production, interest rates, etc.
AND, without storage (battery) most of the solar energy production is wasted in private installation as peak production is midday when consumption in homes are the lowest and no solar help in the morning or evening when it’s needed. Yes, you can still get paid in some countries to feed the grid but it’s predicted to reverse in the coming decade and in southern Europe you already only get a fraction for what you sell compared to the purchase price. Solar panel prices have dropped, now battery prices need to follow and bidirectional charging of cars need to get traction.
Not mentioned here yet is that many existing large buildings, like warehouses, don’t have a roof that is built to support the weight of solar panels. So, while it looks like a no-brainer in terms of available space, the construction doesn’t allow for it. I believe there are also buildings where it isn’t possible due to possible fire hazards (regardless of how well justified this is).
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