More than two factors determine actual annual production. But first, we need to determine the goal we want to achieve:
- Do we want to produce electricity for the market?
- Would we like to cover our own annual electricity needs, so-called “net metering”?
Calculating peak power
After we know our primary goal, we can determine the peak power of the powerplant. In the first case, we want our powerplant to be as large as we can afford. We must first figure out how much electricity is consumed annually in the second case. We don‘t want to overproduce, as excess electrical energy is not billable in most net metering cases and is lost, from the customer’s perspective. Information on consumed energy is usually recorded on the bills.
To get annual
consumption, we must add up all received statements in the past year. Better still, if we have data for more
than one year, we can see the consumption trends and make additional adjustments to determine the actual
needed peak power more accurately. The annual con-sumption value we get is in kWh, so if we want to get the
approximate peak power in kW, we must divide it by the approximate time of annual sun radiation at the site
location in hrs, which can be obtained from the national weather agency or the Global Solar Atlas.
Selecting the correct peak power
In any case, we are restricted by physical limitations. One is maximum peak power determined by connection point capacity, and the second is the available space for installing PV panels. Connection point capacity determines how much power can be received from or sent to the net-work.
For B2C cases, connection point capacity depends on the size of the fuses. Still, the actual capacity of the connection point can be higher, so in that case, you can apply to the network operator to increase the capacity, but that can result in higher connection costs that must be considered in terms of return on investment. Available space determines how many PV panels we can install on the roof, which determines how much solar energy we can capture and how much peak power we can generate. So, in the end, the powerplant peak power is determined by the smallest value in the condition chain.
Calculating offer value
Selecting the right equipment
Now that we have determined the system size, we can choose the best equipment for our case. We need to
select the photovoltaic panels and the inverter. When selecting an inverter, we need to pay attention to the
support of other equipment located on-site; some inverters do not have battery support. We should add a
power optimiser that is compatible with the inverter for better performance, but this is optional. The diagram
below shows the most common layout used in domestic applications.
Diagram of the main components
of a photovoltaic power plant
The DC/AC inverter can connect to all PV modules but supports specific PV optimisers and Electricity storage units (Batteries). In addition to selecting equipment, we must provide work norms related to the quantity of specific equipment to calculate work time and effort, and the price we need to charge for installing it.
The norm for installing one PV panel is one person/hr and €15 /hr. If we have sold 120 PV panels, that must
result in 15 person/days and a cost of €1,800 to install the PV panels on the roof.
Finally, we must calculate travel costs (distance and travel time from headquarters to the site loca-tion). We
must provide a mechanism to retrieve the distance between two addresses and travel time from Google maps
or similar services. Then we must combine the retrieved data with the norm to calculate travel costs.
Distance from Verovškova 55A, 1000 Ljubljana to Ulica Vita Kraigherja 5, 2000 Maribor is 128 km, and the estimated travel time is 1 h 23 min. Combining this information with our norm:
- Number of workers: 5,
- Transport costs: €0.38/km (2 * 128 km * €0.38/km = €97.28) and,
- Worker travel price: 10% of €15/hr (2 * 5 * €1.5/hr * 1.4 h = €21).
We get the total travel cost when we multiply travel costs for one visit, €118.28 with estimated workdays
needed to complete installation.
Offer sample calculation - photovoltaic specific
List of available subsidies
There can be multiple subsidies available to promote the ESCO product and these can impact whether the
project is worth doing. Subsidies may differ depending on the country, the ESCO product category, and
equipment specifications. Therefore, we provide a mechanism to choose from the list of all available subsidies
based on the selected country, category, and selected equipment. The actual subsidy amount can be a fixed
value or calculated based on product charac-teristics or the scope of the genuine offer.
We can have a subsidy for Heat pumps, but not for all Heat pumps, just specific ones with an efficiency factor
COP higher than 2.5
The subsidy can be defined as €180 /kVA and must be calculated €180 /kVA * 13.83 kVA = €2,494.80
In Part 4 (or in e-book) you can also read about:
- CALCULATING PREDICTED ANNUAL PRODUCTION
- CALCULATING ROI