As we are nearing the end of the avant-projet and playing with @Lee’s wonderful simulator, I wanted to submit two ideas. I am aware that one of them would be a reopening of a decision already made, and I am not pushing it at all. I do want to see how it lands, though, in the light of how the discussion is evolving – with particular reference to the plenary of 2025-04-26.
So, two ideas. You could in principle have either, or both, they are not mutually dependent, not mutually exclusive. If combined, they would give rise to a solar and frugal Reef.
The frugal Reef
Easy: sell the Reef zone as a unit, increasing the number of sellable m2 by 66. This brings the Casco price down to 3,368 x m2, equivalent to 2,783 hTVA.
Additionally, we save another ~39K on finishings of the common spaces. The imaginary unit in the Private unit tab of the simulator goes from 448,186 down to 434,776, a saving of 3%.
The Solar Reef
This is based on the willingness to invest in energy sustainability by many full members in the plenary.
Drop solar panels and batteries from the budget, but create an energy community – call it Torpedo.
I have done some calculations that go like this: at current prices, The Reef should consume about 120,000 KWh per year (this is based on a quick research and not on the very dodgy numbers from WALK). We produce part of that on our roof, and Torpedo sells it to us. Based on this article, the benefits are substantial: we would pay only 11 cents per KWh bought from Torpedo (vs. 33.5 cents from utility companies). ON top of that, Torpedo would get 8 cents per KWh (feed-in tariff), instead of zero.
I extrapolated to the entire Reef (1) the costs of the 51 solar panel + batteries and the 50% self-sufficiency calculated by WALK for Obelix. The result is that going full solar would generate feed-in tariffs of about 12K EUR per year, plus savings of about 13K per year. Buying all those batteries and panels would cost about 180K. All this is modular: you can do it only on one building, only on two, with or without batteries etc.
In all cases, the sum of savings and feed-in tariffs offset the cost of the investment in about 7 years. So:
- We would all be members of Torpedo, and all buy some of our electricity from it.
- People with some extra money can decide to put it into going solar. People on a budget can decide to not do that. It’s super flexible. Everybody is still contributing just by buying the energy from Torpedo.
- We would pay to Torpedo a normal price, topping up the 11 cents per KWh of the energy communities tariff up to the market price (currently 33.5 cents). So we pay the same as we would pay to Engie, BUT the money goes to pay back the investment made by those of us who fronted the money.
- After 7 years, the investment is paid back, and we start to make a profit.
- None of this concerns the Reef’s budget, which actually goes slightly down (no solar panels, and even more if we decide to allocate the roof of Asterix to more solar).
Here’s a version of the solar, frugal Reef based on Lee’s spreadsheet. I added a tab with some back-of-the-envelope calculations about our consumption of electricity and the economics of Torpedo.
Ping @coral-board for now.