Energy community: towards a detailed simulation and future game plan

The Reef
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As a result of today’s meeting with the Facilitateurs d’Énergie, we decided to focus on producing a realistic (as opposed to “rough”, like the one before) simulation of an energy community in The Reef.

This means starting from a fresh copy of the Facilitateurs’ simulation tool – basically an Excel file with a macro – and spending some time working on the encodage and financier tabs.

Step 1. Estimate production and consumption

This is done in the encodage tab.

Frame 1 (Producteur) is going to be the energy community itself (call it Torpedo – an electric fish – to avoid confusions with The Reef). We are type A (pending Sibelga’s say-so, but it is likely that we can get it). The first rough number we got is that we can produce 30K KWh per year. This part of the estimation needs to be checked with WALK.

Frame 2 (Consommeurs) is going to be done by category. I would propose we have 5 or 6 categories:

  1. Studios
  2. 1-bedrooms
  3. 2-bedrooms
  4. 3-bedrooms
  5. Common spaces (alternatively: 5. Common space in Obelix, and 6. Common space in Idefix).

The trick for these is to get to a reasonable approximation of the consumption of electricity for each category. This seems to be exactly the kind of job that the facilitateurs are trained to do, so should be no problem, as long as they know surfaces, PEB, technology for heating and cooling (heat pumps), and things like “we are going to put lighting, heating, cooling of the common spaces on the common electricity meter, as well as the three lifts and a recharge point for electric vehicles”.

This part of the simulation allows us to compute how much money we will save per year.

Step 2. Foresee an investment (and return) profile

This is the part where we look at how we distribute the benefits between investors and consumers within The Reef, and is done in the financier tab. The job to do is this:

  1. Get a quote for the equipment that will generate the amount of electricity in frame 1 of the encodage tab. How much does it cost? This is where we need to ask WALK and maybe others.
  2. Encode Torpedo as a collective investor. It bears the costs, and pays itself back via a share of the benefits. To a first approximation, these include the sale of electricity to the Reeflings, the feed-in tariffs, the certificats verts (unless the Arizona government scraps them, but they are still approved for 2026), and the injection résiduelle, i.e. the electricity sold back to the grid. The latter can not be negative for energy communities, yay!
  3. The benefits for the investor are used to pay back the costs of the equipment, or, to be more precise, to pay back a loan that individual Reeflings, on a voluntary basis, will provide to Torpedo. So, we are all members of Torpedo, and some are also its creditors. Once the loan is paid back, Torpedo starts accumulating a profit: a small pot of common money that we can use for whatever we think is useful.

Step 3. Write a proposal

With the simulator complete, we can play around with the discretionary parameters – essentially, the internal electricity price that Torpedo will charge individual Reeflings. The goal is a fair distribution of the benefits, that allows the copropriété to save (the initial estimation was that a proper solar roof could cover 75% of the common energy costs), individual Reeflings to save (initial estimation: 25% drop in yearly energy costs for the average household) and Torpedo can rake in some money to pay for its equipment, with the idea of paying it back in around 5 years.

Once we have a configuration that we find convincing, we will write it into a proposal and take it to plenary.

Step 4. Find the investors

Once the group agrees that this is something to do, our next job is to ask individual reeflings to invest in Torpedo. I imagine a loan with interest. The goal is for the group as a whole to commit to enough money to pay for the equipment that will generate the benefits of step 2.

Step 5. Investigate incorporation

If steps 3 and 4 are successful, we return to the Facilitateurs and ask them for the information we need to incorporate. We might even stretch the mandate of the helping circle to execution, like writing a statute based on a template, getting permission from Sibelga to incorporate as Type A, bookin a notary (if a notary is needed).

@els , @Sterre , does this make sense?

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Makes sense.

For the info you want from Walk, I don’t think we will get more detailed info than what we got from the avant projet phase. My understanding was that we would dive into more detail during the ‘appel d’offre phase’. I personally would just go with the estimated values from the facilitator, based on 86 solar pannels. I also don’t think more detailed info will matter much for the simulations.
But don’t let me block you if you want to try contacting Walk

At the same time of step 3 (whether in the same proposal or a seperate one), i would also decide on how we want to distribute the energy produced by Torpedo,

In the meantime, i filled in the simulator with the info received during our meeting. The part I am doubting, is tab ‘Financier’, the pourmilles (here i tried to encode sb who invested 10% of the total investment, and owning 1//22 as cote part). But please verify the whole excel

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That’s tricky, because it would be a proposal that does not yet take into account the point of view of those who would provide the financing. The interest on the loan is a cost component for the entire thing. We know from the rough simulation that the savings are large enough to “swallow” a moderate interest, but we might still want to adjust the internal price depending on the rate on that loan. This is why the decomposition in: first, check that there is momentum around the idea by quantifying the benefits; next, raise the funds with an internal loan which must be negotiated.

I do imagine making some examples with different internal prices (scenario 1, scenario 2 etc.).

Additionally, Step 4 must be done after WALK has quantified precisely the cost of the investment. It does not make sense to ask Reefling to invest an amount of money which we do not know precisely.

And finally: it seems that the certificats verts are decided yearly. That is a substantial element, because they go to the producers, that is Torpedo itself. It means that these are own funds of Torpedo, a guarantee towards returning the loans. At 2026 prices we would get very roughly 30,000 KWh x (1.6 / 1,000) certificates at 65 EUR each, that is 3,120 EUR per year for ten years, guaranteed. This makes the loan quite safe, for the amounts he had in mind (about 40K, if memory serves).

One thing we did not discuss with Jean is batteries. Did you bring it up after I left?

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From a quick glance, what is missing:

  1. In the encodage tab, Frame 2, add a type of consumer per each unit type (Studio, 1 BR etc.) + 1 for the common spaces. Try to estimate consumption for each type, maybe asking Jean via email. Note: we forgot to tell Jean we are going to have a common laundry!
  2. In the financier tab, try and simulate the three types of participants: copropriétaire habitant (20 households), copropriétaire bailleur (2 households) and locataire (2 households). But it’s true that, there, I do not understand. Are we to add the pourmilles of each unit individually? Where is that encoded? Why is it not linked to the régistre des consommeurs? Maybe here we need to ask Jean.

If that’s not possible, I would consider all Reeflings under producteur. So, the copropriétaire habitant would have the pourmilles pertaining to the 20 units inhabited by their owners, i.e. all of them except A1 and A4. The propriétaire bailleur and the locataire would have the pourmilles of A1 + A4.

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Hello @els and @Sterre ! We have received a new simulation from Jean, you’ll find it in the Proton inbox. He is offering to continue simulating for us, and that we send him by mail what we want to see.

I propose to use our next meeting to put together a list of questions and additional simulations. Since now we can do simulations ourselves on Els’s laptop, the questions are more important. And my main question is: what about batteries? I see that batteries are not part of this simulation. Is it because he does not recommend them, or because we did not ask? What would the numbers look like with an additional investment in storage?

Also, his new simulation, as I see it, is of a Reef made by:

  • 11 larger units, whose owners also live in, and
  • 11 studios, whose owners rent to others.

The question: is it worth it to simulate in a more granular way (so many studios, 1 BRs, 2 BR, etc.)? My hunch is yes.

This does not need to be a long meeting, 30 minutes online are enough. What do you think?

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  • i see he only send us the file filled during the meeting, he didn’t yet answer to my mail about a more detailed energy consumption for The Reef, based on our types of units (6 3 BR, 8 2 BR, 8 studios + 1 BR),/ number of adults/children we expect to be in the Reef.

I agree. Can you fill in the poll, or shall i launch a new one? New helping circle: starting an energy community - #27 by els

I asked the question after you left. It’s in the report. Basically he said that we have little energy to sell to our regular electricity provider, so this isn’t in our advantage, certainly when the price of batteries is still quite high. He recommends to do the pvt installation and see during a few years what we sell to our electricity provider (as it’s difficult to simulate what our real consumption will be), also check the price evolution of the batteries and evaluate later whether to install batteries, but not at this moment.

  • I thought a bit about what I need as info, to become an investor or not, and - maybe i am the only one - but a possible interest on the investment, the rate in which my investment would be paid back, the price of the electricity we would set,… would not really matter in my decision to become an investor. It depends on 1 and only one thing: do I have the money? I have a limited budget left, but I see still more or less 4 possible topics (reef related, not related to my own unit) on which i could spend this money. At this moment I have not enough clarity to know if/whether I will spend my money on the other topics or not and for some of these topics this clarity will still take months. The only thing I know is that the solar panels investments is something that can easily be done afterwards (if there wouldn’t be enough investors), the others topics cannot be done afterwards.
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For me this is linked to the ‘méthode de répartition’ in the tab 'encodage.
The way I understand this sheet is that it is there to

  1. calculate the money you save by buying part of your energy from torpedo
    the pourmile part des quotités dans l’immeuble, will - according to me - define how much of the energy produced by Torpedo you will receive, as in the tab ‘encodage’ , la méthode de répartition is ‘fixe à N tours’.
    The registre des consommateurs is only there to define the energy consumption. And I think if you would chose for 'methode de répartition ‘prorata’, it would base itself on the registre des consommateurs. (prorata of the enenergy consumption)
    (but i haven’t tried out changing this value yet).
  2. calculates the ‘payback’ time of the investment of the PVT installation. and therefore it defines three ‘roles’: copropriétaire habitant, copropriétaire locataire, locataire.

  • copropriétaire habitant: his payback is defined by the amount of energy that torpedo sells at the defined price to the reeflings (according to a certain pourmille for that person) + what he/she himself save on his electricity bill by bying a part of its electricity from torpedo and not from the regular electricity provider + part of the certificats verts + part of the overproduction sold to the regular electricity provider

  • coproporiétaire : same as above except for the gain on his own electricity bill

  • locataire: no payback, as no investment, but you can see ‘what he wins’ by the energy sharing

→ i would not do it like that For me the payback of the solar pannels should not be done with the money you gain personally by buying electricity from Torpedo (and not for the normal electricity provider). For me the payback should purely come from:

  • the kWh Torpedo sells to the reeflings, at the electricity price to be defined by us
  • to be decided : maybe the kWh the commons use from the kWh’s produced by Torpedo, at the electricity price to be defined by us
  • the certificats verts
  • the overproduction sold to the electricity provider.

And each investor receives a part of this money proportionally to his/her investment, till his/her investment is paid off, maybe with a modest interest included.

This - for me - is not possible/correct, as all energy produced by the producers would first go to the producers. So here all the energy consumed by the reeflings would not be shared but mainly go to the individual counters of reeflings.

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You are probably correct. So the thing to do to refine the analysis would be to select prorata, then generate the five types of consumers as per my previous post. Would you be up for doing that?

This is because how much money you save does not only depend from whether you are copropriétaire habitant or not, but also on the size of your unit.

Financially, you are right. But economically, the advantage of even making that investment comes indeed from the saving in electricity bills. Additionally, an energy community is not made only of producers, but of producers and consumers. The role of consumers is as important as that of the producers in enabling the economies in question.

On top of that, consider someone who is both an investor and an inhabitant. That person’s investment will indeed be made more attractive by the reduction in their private energy bill. In a way, as an investor-inhabitant you do not need to be compensated so much for the loan you give to Torpedo, because you get some advantages in the form of a reduced energy bill. Even if Torpedo pays back te loan in five years, the investor-inhabitant has more money than they would have had without the investment by the end of the fourth year.

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This may be too detailed for our simulation, but good news on the VAT rate on heat pumps: link, pawalled and in French.

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Els, Alberto, you’ve probably noticed that I haven’t contributed a lot. As I said during our first meeting, I would like to take a more observant role for now, having little knowledge (read: absolutely none) about the subject. I wish to learn more about it, though, so I am taking my time to try to understand everything you are writing here. Just know that I’m still into it with you.

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No worries! You’ll catch up at the next meeting. By the way, in the other thread Els has created a poll to decide when that would be. Want to look at it?

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Yes, I voted when she posted the poll. I don’t have a lot of availabilities the coming weeks.

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yes, coming weekend, if i get the data from the facilitator

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hi @alberto @Sterre

  • no answer yet from the facilitator on our question for a more detailed energy consumption for the commons and reef-units (but there only back to work since last friday).

  • i adapted in the simulator the value of ‘répartition’ to ‘prorata’, but is still requires to fill in ‘part des quotités dans l’immeuble’. I see the ‘part des quotitiés’ is also used to calculate the value of ‘economie sur le compteur commun’…

  • But I wonder if encoding these ‘part des quotités’ is really necessary? What results do we really want to obtain/play with?

    • the price of the electricity produced by Torpedo and sold to the various units → tab ‘Tarif’

    • based on the above price: calculate what ‘revenue’ Torpedo will get→ for this i added in the simulation file, extra formulas to calculate globally what this would be (not per category), and following this revenue, what the payback time would be for the solar installation (column K, L,M). I guess we will pay back the investors, proportionally to the money they invested, so the payback time should be equal for all investors?

    • we can simulate - based on the set price- for one or two units, what they would ‘gain’ on their electricity bill by buying electricity from Torpedo, but that’s more informative. So in that case we would only need to fill in the ‘part des quotités’ for one or two units, not more. Or am i missing something?

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We would like to know what kind of energy bill Reeflings can expect with and without the energy community, based on the size of their units.

Also, a breakdown by unit type makes the estimate of the overall consumption more precise.

Yes, we pay back proportionally to the money invested, and yes, the payback of the loan is the same for everyone. But the speed at which each person recovers their investment also depends on how much money they save on energy, which depends on how big their unit is.

Numeric example

Suppose Alice lends 100 EUR to Torpedo, with the agreement that it will pay her back in 10 years, 10 EUR per year. Meanwhile, because the energy community is there, she is saving an extra 5 EUR a year.

So:

  • The first year, Alice invests 100. She gets a payback of 10 and a saving of 5. At the end of the year she has 10 + 5 - 100 = -85 EUR , or 85 EUR less than she would have without the energy community.
  • The second year she gets again 10 payback and saves 5. Now she has 10 + 5 - 85 = -70 EUR, so 70 EUR less than she would have without the energy community.
  • […]
  • The 7th year she gets again 10 payback and saves 5. Now she has 10 + 5 - 10 = 5, so 5 EUR more than she would have without the energy community. The investment is paid back at some point during the seventh year. From now on, she will have more money in the bank than she would otherwise have had. After 10 years, she will still have the 5 of the 7th year, plus 10 x 3 of repayment of the loan, plus 5 x 3 of savings = 5 + 30 + 15 = 50.
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yes, i understand what you are saying.

I just think that this simulation is very theoretical and will largely depend on your personal behaviour, number of people in your household,… It will also depend on the repartition method we will chose later. To use this simulation for the whole Reef and look at it globally, i don’t have a problem, but to give a simulation for a type of unit, i find less usefull. I personally think the result might have a correction margin of 100%. So personally i would do it for a 2 BR and say this is what you could safe approximately, and that’s it. If you than have a 1 BR, it will be a bit less.

But it’s not a lot of extra work to do it for the different type of units, so ok to do it.

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Yes, indeed this is contingent to the internal price of electricity.

I am looking for a value proposition to bring to people who, after spending a lot of money in a Reef unit, might still have a bit of juice left to pay for this bit. They will want to know – based on parameters like unit size, as you say – what their numbers are likely to look like.

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hi @alberto @Sterre ,

The facilitator came back with a reply to give us an energy consumption which is closer to The Reefs composition.(see proton mailbox + simulator file)
He defines two profiles, this time also taking into account the heat pumps:

  • profile 1 consuming 3000 kWh/year (units with 1 adult + 1 bedrooms with 2 adults) → 11 units
  • profile 2 consuming 4000 kWh/year (units with 2 adults with or without children) → 11 units

He didn’t really reply to the question of the 'common washing machine ', i asked him this question again.

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Thanks Els. Did he explain why he thinks that’s a good approximation?

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hi alberto,

No, he didn’t really explain.

When I wrote to him i was even more detailed than studios, 1 BR, 2 BR and 3 BR’s.
I also specified the number of adults and children for each unit (and made an estimation for the ones not sold) and shared also high level the m2 of our units.

So basically I arrived at 8 possible different profiles.
These 8 profiles were reduced to 2 profiles by Jean: petit and grand.

  • 5 studios occupé par 1 adulte => 3000 kWh/an

  • 2 1-chambre occupé par 1 adulte (plus au moins 66 m2) => 3000 kWh/an

  • 1 1-chambre occupé par 2 adultes (plus au moins 80 m2)=> 3000 kWh/an

  • 3 2-chambres occupé par 1 adulte, sans enfants (plus au moins 90 m2) => 3000 kWh/an

  • 3 2-chambres occupé par 2 adultes, sans enfants (plus au moins 100 m2) => 4000 kWh/an

  • 2 2-chambres occupé par 2 adultes et un enfant (plus au moins 90 m2) => 4000 kWh/an

  • 1 3-chambres occupé par 2 adultes sans enfants (113 m2) => 4000 kWh/an

  • 5 3-chambres occupé par 2 adultes et deux enfants (plus au moins 120 m2) => 4000 kWh/an

PS Jean proposed to plan a new meeting in case we wanted to discuss the figures…