Solar Energy Value
This example shows how you can track the value of produced energy with Variable Market Value analysis.
Intro
We have a solar energy setup, where we can use all produced energy locally at the site. So there is no need to sell the produced energy back to the grid.
The amount of produced energy will vary greatly based on the time of the year, weather, and also based on how we could consume energy (either by using it, or by storing it into batteries).
At the same time the price of electricity will fluctuate on the grid.
With this setup, it would be interesting to know what is the value of produced energy, even though no real commercial transactions have been happened between you and the local energy company.
To answer that question, we will use Variable Market Value analysis.
Setup
Produced Electrical Energy
First you need to know how much energy we have produced over time. Ideally this should be the same period of time as what is used in the electricity market. In this example we will use one hour resolution.
We will record produced energy to transactions by automated system, which will read it directly from the Solar Charge Controller. The amount of these automatically generated transactions won’t be any problem to tacker, as it can easily process hundreds of thousands transactions.
2024-03-20T08:00:00 SolarPanels:Array:1 0.4638 kWh Sun 2024-03-20T09:00:00 SolarPanels:Array:1 1.671 kWh Sun 2024-03-20T10:00:00 SolarPanels:Array:1 3.7428 kWh Sun
With this setup we will have the energy data by hour, and we can use this information in the next steps.
Price of Electrical Energy
The price of electrical energy varies hour-by-hour, but there are other aspects to total price of it, including fixed contract fee, transfer costs and taxes.
In this example we will use two different price models:
- Use-at-site
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In this case we would like know how much it would have cost to buy used electricity. To calculate that we have to know what is the energy price with transfer fee included, with taxes.
- Sell-to-grid
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In this case we would like know how much profit we would have made if the energy was sold back to grid. For net price of energy, we have to subtract from the energy price the transfer fees and taxes.
We will use two different pricedb files for these use cases. The price of the energy is recorded as Euro cents.
In the first case, we would have to had pay price and transfer fees, if we would have been bought the energy from the grid.
P 2024-03-20T07:01:32 kWh 9.771 c P 2024-03-20T08:01:37 kWh 13.842 c P 2024-03-20T09:01:37 kWh 16.739 c
Compare this to price structure when produced energy is sold back to grid - the tax and transfer fees are subtracted from energy price:
P 2024-03-20T07:01:32 kWh 0 c P 2024-03-20T08:01:37 kWh 3.322 c P 2024-03-20T09:01:37 kWh 6.219 c
This highlights that price could go to zero or even negative when sold back to grid with fixed fees.
Produced Energy value
Energy used at the site
Total savings when all energy could be used on the site (unit is Euro cent):
tackler \ --config examples/solar.toml \ --reports balance
Balance report of energy value
Report Time Zone
TZ name : Europe/Helsinki
Commodity Prices
Time : At txn time
Commodity : kWh
Value : - c
Balance Report
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1320.98 1320.98 c SolarPanels:Array:1
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1320.98 c
So for these four example days, the value of energy has been about 13.20 €.
Energy sold to the grid
Virtual value of energy, if it had been sold to grid (unit is Euro cent):
tackler \ --config examples/solar.toml \ --reports balance \ --pricedb examples/solar/txns/se-sold.db
Balance report of energy value
Report Time Zone
TZ name : Europe/Helsinki
Commodity Prices
Time : At txn time
Commodity : kWh
Value : - c
Balance Report
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338.25 338.25 c SolarPanels:Array:1
=======================
338.25 c
On the other hand, by selling it, we would have earned 3.38 € - that’s about value of one portion of ice cream.
Full Example
The full solar energy value example is located under tackler example folder, and it’s executed as part of the Tackler’s CI/CD jobs.