Would a DC house be better when run by solar? What happens, when the sun shines, the wind blows and my battery is full? In Germany the Grid provider doesn’t pay a reasonable price for the electricity you put into the grid. It might vary around sometimes less than 7 Cent per Kilowatt-hour (kWh). Whereas you pay about 30 to 45 cents if you buy a kWh from the grid.
The tendency is even, to shut solar arrays down, to beware the grid from overload.
Do you want to lose the solar energy in times of overproduction?
Of course you don’t wanna lose solar energy. Therefor the industry provides so called Energy Managers.
These electrical devices come mostly in combination with an app where you can monitor your energy production and your consumption.
You can charge your Electric Vehicle (EV) when the sun reaches out your demand.
And even if you don’t work at home the energy management system can switch on the heat pump, the washer or the air-condition.
How much do Energy managers for DC Houses cost?
solar hydrogen electrolyzer management system pv
Energy managers are brutally expensive because the development and the know how needed is enormous.
At the end, the electrician and the parts themselves will cost a lot.
Isn't there an easy low tech solution to use the surplus power?
Back in the days the management was done by a schmitt trigger Relay.
Is the alternating current (AC) conversion a big loss?
All converters have a loss. The bigger the cooling rips or even ventilations are the more energy is inverted to heat. The industry claims an efficiency of 96 Percent.
But if we look at the system in a bigger scale, we will have the following losses.
Whereas Inverters are very expensive, you get Buck Boost converters for very cheap.
Notebook charger for 12 V offgrid solar system Laptop Netzteil 12 auf 19 V off grid solar
Advantages of a DC-House
How to get more Energy with less Solar. You can save a lot of money by using DC in your household because the wires can be much smaller. You do not need inverters and you do not have conversion losses.
Save energy with efficient dc home appliances
A great way to use more PV is a variable voltage DC Fridge
A fridge is found in almost every house and it quietly consumes a lot of energy. Due to mass production AC fridges are much cheaper than DC ones. The DC RV and Boating equipment is even more expensive an not really fitting to a household.
Check out this amazing DC Fridge made in USA.
Save on lighting
This entrepreneur claims to save up to 800 Dollar per household on wiring by going dc.
Ideas on interesting components for a DC house
First advise is:
Use your direct current (DC).
Your powerwall, Lithium-Ionen, Redox-Flow Battery also stores DC Energy.
Many appliances use DC.
All Audio Visual and Entertainment devices, such as Laptop, TV, Modem all cordless tools use DC-Current.
To charge your laptop or notebook directly you only need a Buck Boost converter.
And most important, Hydrogen which is the long term storage in 2021 for households and domestic use is made with DC through electrolysis of water.
All a Schmitt Trigger does, is switching on or off a relay depending in the battery voltage measured.
Today this task is done by a tiny microchip.
Your Solar regulator will switch to float charge. Float Charge – the battery has completed charging and is in maintenance float charge.
This 15.8 x 13.8 x 2 cm small and 20 Gramm heavy device cost only 10 € and can do the same as a Energy Manager.
You can buy the
KKmoon 12V DC Voltage Detektion Charging Entlastung Monitor Test Relay Schalter Control Board Modul¡
easily.
12V EASY RL V2.3 Multifunktionales Relaismodul (gotronik.pl)
Features:
Digital display DC voltage detection, control the relay output.
Adjustable voltage limit: 0-99.9V.
When the measured voltage is lower than the lower limit or higher than upper limit value, the relay works.
Can be used for voltage detection switch, battery over/under voltage protector or discharge meter.
Notice:
The relay control panel features single mode voltage detection function.
Max. trigger current is 10A(AC 277V, DC 30V), please don’t connect it with load over DC 30V.
This relay module is not suitable for lithium battery discharge.
Polarity for voltage detection can’t be connected reversely, user should connect the wire after power off.
Specifications:
Relay Voltage: DC 12V
Working Power: DC 10-16V
Voltage Detection Range: DC 0-99.9V
Error: +/-0.1V
Timing Range: 0-999 minutes cycle
A set of transformations(normally open/normally closes)
Contract Load: 10A/277V AC, 10A/30V DC
Contract Resistance: ≤100mΩ（1A-6V DC）
Mechanical Durability: >10 million times
Electrical Durability: >100,000 times (10A-250V AC)
Standby Current: 16mA 12V, Digital Display Closed Smallest 6mA/12V, Relay Timely 45mA/12V
Working Temperature: -40-85°C
Dimension: 50 * 40 * 20mm
Weight: 27g / 0.95oz
Package List:
1 * Relay Switch Control Module
KKmoon 12V DC Voltage Detektion Charging Entlastung Monitor Test Relay Schalter Control Board Modul¡ |
Conclusion on the dc house with solar
Of course this is a DIY approach. We would never suggest such a lumpy setup to our customers but it eventually shows how easy and cheap it could be to switch on loads when renewable energy is abandoned.
In order to reduce the carbon emissions maybe a grassroot movement is needed to provide the population the knowledge how to use renewable energies cheaply.
If you need specific consultancy, feel free to contact us.
international MEP HVAC engineering: Better efficiency, lower cost