I hope thats not offtopic, but i found no better section to place that information.
It is not easy to understand how to handle the option "PAngV" so here is a document, which could help.
In NopCommerce the PAngV, which I also refer to as the base price, has been used for some versions. The law itself also regulates other things such as the indication of value added tax and others. More on that later.
The base price is the price that refers to one liter, one meter, one kilogram or one square meter.
Not every product has to indicate the package price and the base price. Part of what already forms a unit as a whole, such as a car, is only shown with a product price. However, if the package contains 500 grams of sugar, the base price must also be indicated as one kilogram.
NopCommerce solves the problem in such a way that you can fill in additional fields by specifying a checkbox so that the base price is determined automatically. However, the prerequisite for this is the prior declaration of the necessary conversion units. You will find the point for entering the conversion units under "Configuration > Shipping > Dimensions". There then in the section 'Weight'.
Enter all necessary units under'Weight', i.e. meters, centimeters, millimeters, milliliters, liters, etc. Since NopCommerce normally only stores weights here, the "Mark as main weight" button must not be used in this context. Unfortunately, the base price calculation takes your information from exactly this section, so that we indicate all our other units here.
The PAngV regulation says that we have to convert to liters, kilograms etc.. In other words, you always enter a "1" for "ratio to main weight".
If you have products in packs of milliliters, you also create a unit "ml" there, and then enter "1000" for "ratio to main weight". Proceed in the same way with the other units.
After completing the preparatory work, you return to entering the product data.
If you tick the field "PAngV", there are other fields that must be filled in.
For example, in the "Amount in product" field, enter 250 for example, then select the milliliters in the "Product unit" field and always enter the "1" in the "Reference unit" field and always the "liters" in the "Reference unit" field for liquids.
It is a little confusing why these things run under weight and why you have to enter the reference value here again.
I see potential for improvement here at NopCommer. First, the units of measurement should be generalized and there should be sets of units that have their own reference unit. The menu item in the configuration does not necessarily fit under "Shipping".
Now I would like to close the circle, I wrote at the beginning that the regulation also deals with other things. For example, the price including VAT must be specified and this must also be shown. The other things can be found in the following text of the regulation.
The legal regulation for the indication of the unit price is complex and is regulated in Germany by the "Price Levy Ordinance" (PAngV).
The law covers many things related to prices and consists of 11 paragraphs and an appendix.
The original text of the law can be found at: https://www.gesetze-im-internet.de/pangv/.
Since the description is in German and who doesn't know the language, I can recommend the online translation of DeepL at http://www.deepl.com In my opinion, she works best from the current machine translators.