Compare electricity agreements: what do you pay on top of the spot price?

At the same time, part of the electricity bill is linked to things other than the choice of electricity company. The grid company, the time of consumption and the applicable taxes affect the bill. If they are mixed up with the supplier’s own prices, an offer can look cheaper without the comparison actually being equal.

Start with your current agreement

Find the latest bill and the terms for the product. Note the subscription, energy mark-up, any payment fees and how the energy price is set. If the name of the agreement does not explain this, find the price list or ask the supplier.

Then note the consumption in the period you want to calculate. An earlier annual consumption is a good starting point if the household is unchanged. If you have got a heat pump, bought an electric car or changed the number of residents, the comparison should also include a new consumption scenario.

You do not need to predict everything precisely to get started. It is better to try two reasonable levels than to treat one old figure as certain.

Tell the spot price and the total electricity price apart

The spot price describes the market price of electricity in a particular area and time interval. It can be used to understand developments in the market and differences through the day. It is not on its own the amount that ends up on your bill.

On top of the spot price can come the electricity company’s mark-up, grid charges, taxes and VAT. Fixed payments come in addition to the running price. A chart can show some or all of these parts, which is why it must be clear what you are looking at.

A negative spot price does not necessarily mean free electricity at the socket. Other price components can still make the total payment positive. Conversely, a calculator must be able to handle a negative total variable price if the actual data and terms give that result.

Same unit and same VAT basis

Check whether the figures are given in øre or kroner and per kWh or MWh. One MWh equals 1,000 kWh. Unit differences can cause large errors if they are overlooked.

Also use the same VAT basis in the comparison. A price including VAT must not have VAT added again. If a price list mixes amounts stated in different ways, they must be normalised before they go into the calculator.

Subscription and energy mark-up must be seen together

A subscription is paid according to the agreement’s fixed terms, while an energy mark-up normally grows with consumption. The most favourable combination can therefore change with the household’s needs.

At a low consumption, a fixed payment can weigh heavily per kWh. At a high consumption, a small mark-up on each kWh can become the biggest difference. An electricity agreement can therefore not be called the cheapest for everyone on the basis of its monthly subscription price alone.

Use the calculator for comparing electricity agreements to see both the supplier items and the total modelled bill. The two views help you tell apart what you pay and which parts a change of supplier can change.

A concrete example of the difference between two agreements

Imagine two constructed spot products with the same other price basis. Agreement A has no monthly subscription and a mark-up of 0.15 DKK per kWh. Agreement B has a subscription of 25 DKK a month and a mark-up of 0.05 DKK per kWh. Other fees and discounts are left out of this example.

At 2,000 kWh a year, A’s mark-up costs 300 DKK. B costs 300 DKK in subscription plus 100 DKK in mark-up, that is 400 DKK for these supplier items. A is 100 DKK cheaper under these assumptions.

At 6,000 kWh, A’s mark-up costs 900 DKK. B costs 300 DKK in subscription plus 300 DKK in mark-up, that is 600 DKK. Here B is 300 DKK cheaper. This is still only the difference in the chosen supplier items, not the whole electricity bill.

Find the consumption where they cost the same

The difference in subscription in the example is 300 DKK a year. The difference in mark-up is 0.10 DKK per kWh. At 3,000 kWh the chosen supplier items are therefore equal. Another fee or a discount can change the break-even point.

This type of calculation is useful if you expect your consumption to change. A new electric car or heat pump can make a previously good agreement less attractive without the supplier having changed its price.

Introductory offers must be spread over the right period

A welcome discount can lower the payment at the start. To understand the offer, you need to know the discount period and the price afterwards. A product that is cheap in the first months can rank differently over a whole year or longer.

Calculate with your actual expected agreement period. Show both the total price for the period and the price without the introductory benefit. A lasting annual price should not be presented as if the same one-off discount came back every year.

Also check whether the discount requires certain actions or applies to certain customers. An offer whose terms you do not meet should not count as a saving in your result.

Fixed price and spot price meet different needs

A fixed energy price and a price that follows the market cannot be compared simply by using one random day’s spot price. Choose a common consumption and a clearly described price development for the period.

A historical calculation can show what an agreement would have cost with an earlier consumption. That is something other than a forecast of the next bill. Future market prices are unknown and must therefore be handled as scenarios when the calculation goes beyond known price data.

Also read which parts a fixed price actually covers. A fixed energy price does not necessarily mean that all items on the electricity bill are locked for the whole agreement.

Grid tariffs can make the timing important

Payment to the grid company can vary with time and period. If you want to find cheap intervals for charging or other large consumption, the relevant tariff must therefore be included together with the energy price.

This can change the order of the cheapest periods compared with a pure spot price chart. The choice of grid area must match the address. The electricity company and the grid company are different roles, and changing supplier does not in itself mean that you freely choose another local grid charge.

The electricity bill calculator can show the contribution of each item. When shared costs are visible, it becomes easier to see whether a price difference is due to the agreement or to a change in consumption and timing.

Shift consumption that can actually be shifted

Car charging and some appliance programmes can often be planned within a time window. Other needs arise when they arise. There is no reason to treat the whole household’s consumption as flexible if that does not match everyday life.

Start with a specific task and a deadline. How much energy is needed, when can it start at the earliest, and when must it be finished? For charging, the available power is also needed to know whether the plan can be carried out.

In the cheapest electricity period calculator you can compare suitable start times. An appliance that must run a whole programme needs a continuous run. A supported, interruptible charge can be distributed differently.

Compare with a meaningful baseline

A saving needs a basis for comparison. It can be starting now or starting at your usual time, if both plans can be carried out with known prices. The same energy need must be included on both sides.

A large difference to today’s most expensive interval does not necessarily tell you what you personally save. If you would never have used electricity at that time, it is a different comparison from your actual habit. The calculator should therefore show which baseline is chosen.

Use published prices and know the limits of the data

Price data can have different interval resolutions depending on the period. A calculation must follow the actual timestamps and durations rather than assume that every day consists of 24 equal price intervals.

Tomorrow’s prices can only be used once they have been published and are available in the data source. If part of the planning period lacks prices, this must be shown. The missing intervals must not be treated as free or filled in with a certain figure that does not exist.

Energi Data Service is a public source of relevant market data. The final price for a particular household also requires the right tariffs, taxes and agreement terms. A data source for spot prices is therefore not on its own documentation of a complete consumer price.

Assess offers and calculations separately

A product card can show an offer from a partner. It must be clear when there is a commercial relationship. A ranking by total price must at the same time follow the calculated figures and the same basis of comparison for the products included.

Check the date of the prices, and read the current terms with the provider. An overview can be useful without covering the whole market, as long as its scope is clear. Pay particular attention to products where a low price depends on a temporary condition.

On Calculus.dk the calculation is the starting point. You must be able to see the result and the assumptions before you consider a referral. Information about a possible saving must be traceable to your consumption and the actual items.

Save the assumptions when you choose

Note the date of the offer and the amounts you used in the calculation. Then you can later check whether a changed bill is due to more consumption, other market prices or new terms. Also save the expiry date of any discount.

A calculation result is a snapshot of certain assumptions. It is therefore useful to repeat the comparison when a major change occurs, rather than switching after every single expensive day on the spot market. A single high daily price does not on its own tell you that the supplier’s mark-up has become more expensive.

Make your own comparison

Collect annual consumption, subscription, mark-up, fees and any discount terms for the agreements you are considering. Use the same consumption in the calculator, and look first at the supplier difference. Then examine the total electricity bill with your relevant consumption profile.

If you have flexible consumption, you can continue with the cheapest electricity period and set a realistic deadline. That way you treat two options separately: choosing an agreement that suits your consumption, and moving some of the consumption to better times. Both must be justified by your figures before a saving is counted in the budget.