Close-in boiler and teruglevertarief

[HvdW]

In the Netherlands a new electricity tariff has been introduced for returning energy to the net.
This makes it profitably to return less energy to the net.
One can charge a battery, one can charge a car battery, one can wash during sunny hours in summer and more.

I am thinking about the following usercase.
In our house there is a distance of about 3-4 meters between the gas boiler and the kitchen tap.
To get warm water in the kitchen one has to wait 10-20 seconds in which time only the water pipe will be preheated at the cost of expensive gas without getting the warm water out of the tap.
I'm thinking about installing a close-in boiler which will heat the water using PV power. (if enough PV energy is present)
Problem is that these close-in boilers have an electric element of 1500 Watt.
How nice it would be to make the element use 500, 1000 and 1500 Watt or maybe even 250 Watt to heat up the water.

Even nicer if this close-in boiler would have a bypass to use gas-boiler-heated water in case the temperature inside the close-in boiler is less than 40˚C.
I think this is an economic way to use self produced energy directly for own consumption.

Other measures:
- Car battery charging at times when high PV output is present.
- Temporary switching off air to air heat exchanger while water cooker or oven is using electricity
Balancing power consumption in house is rather easy with dzvents.

I asked boilermarkt.nl: there are no close-in boilers available where one can regulate power consumption.

Share your thougts here please.

[Toulon7559]

Even nicer if this close-in boiler would have a bypass to use gas-boiler-heated water in case the temperature inside the close-in boiler is less than 40˚C.

This 'wish' is easily met if you fit the close-in boiler in the hot-water pipe between gas-boiler and tap,
because once you take hot water from the close-in boiler, it will be replenished from the gas-boiler

[HvdW]

... once you take hot water from the close-in boiler, it will be replenished from the gas-boiler

Which means that it will be filled with warm water from the gas boiler.
That's double costs!

[waltervl]

You could try to find a dimmer that has enough capacity and dim down a 2000W standard close in boiler to your needs.
Something already discussed here https://gathering.tweakers.net/forum/li ... /2156866/0 in dutch.
Somebody also made a test setup and made a video: https://youtu.be/p3FhRNOLLjQ in dutch.

Also make sure the return on investments costs are positive.

[HvdW]

Thanks Walter, that is helpfull.
I think of a setup using KEMO M028N and KEMO M150
Still: help is much appreciated.

Return on investment:
Prices of secondhand close-in boilers on Marktplaats are relatively low.

[Toulon7559]

Which means that it will be filled with warm water from the gas boiler.
That's double costs!

If you want to bypass your closein-boiler, you will need some remotely controlled tap.
Such selectable bypass is not free of charge.
Related question: how to realise online, remote control of this bypass based on measured watertemp of the closein-boiler?

IMHO you have to make a choice:
either economics (= simple construction with boilers in series), or convenience (= quick supply of hot water)