Let’s produce our own electricity

Everyone connected to Spanish electric grid had a good scare when on the coldest days of the year, around the 11th of January the Spanish electricity wholesalers announced that the price of electricity has reached its highest value since December 2013. The price boom has intensified in the last hours of the afternoon, when the cost of the megawatt hour (mwh) exceeds 92 Euros, a very high quota if you take into account that just a year ago the same mwh was worth 60 Euros, 33% less. 

The overheating of the electricity market will have a real and immediate impact on the bill of the households that have contracted the old regulated tariff, now called Small Consumer Voluntary Price (PVPC). This system replicates hourly the wholesale price of the energy market, with an approximate repercussion of 35% on the total cost paid by users. The remaining 65% consists of tolls and taxes that remain frozen. In this way, experts recommend to concentrate as much as possible the electricity consumption in the hours in which the mwh is cheaper. But to escape the tariff is going to be almost impossible, since the average cost in the day as a whole is at 78.83 Euros. The cheapest hours are concentrated between 00.00 and 08.00 hours, when there is a lower electrical demand.


An investigation of the facts.

The National Commission for Markets and Competition (CNMC) has initiated an investigation to see if the increase in light is due to market factors such as the lack of rain which reduces the weight of hydraulic dams in the market and raises of coal, the increase in oil prices or the lower exchange of electricity with France due to the stoppage of some of the country's nuclear plants but I will bet my right hand that at the end of the day nothing will happen, at most a stupid low fine will be imposed together with a warning to the main electrical companies not to be naughty boys again…


Produce your own electricity.

Since the adoption of the Royal Decree on Self-consumption (900/2015), there has been much talk about whether it will work or not. There is no doubt that installations (type 1) of up to 10 kWp are exempt from any charges so a good development of this segment of the market are expected, most of which will be photo-voltaic systems for homes. The RD also states that the energy poured (surplus) from these facilities to the distribution network is not paid for.

In residential self-consumption facilities, the entire production of photo-voltaic panels can be used. Some system offers the possibility of being configured in three different ways. "After the approval of the RD, the most appropriate configuration is the one that combines the hot water heating (ACS) and self-consumption (giving priority to self-consumption), and allows to take advantage of 100% of the energy produced by photo-voltaic panels, without the use batteries.


The electricity (direct current) generated through the panels directly feeds the DC resistors in the water tank and, therefore, the effectiveness of the heating is very high.

A set up that works.

This set up is equipped with a function that allows the direct current (DC) from the photo-voltaic panels to be redirected automatically to another electrical appliance. This operation is based on potential free connection (12V AC).

If, for example, the heat pump is switched on, the power is automatically redirected to the inverter. The inverter will start generating alternating current (AC) for the consumption of the heat pump. If the production of alternating current by the inverter is the same as the consumption of the heat pump, the heat pump operates without consuming electricity from the distribution network. When the heat pump shuts off, the system automatically redirects the current to the tank to heat the water. This process is carried out several times a day, and in case the heat pump is used in summer to cool down, the system works this way throughout the year.


Total control.

It is also possible to connect other appliances such as air conditioning, electric boiler, etc. In addition, more than one device can be connected in parallel. The operation of this system takes maximum advantage of the energy production from the photo-voltaic panels and ensures that no power is poured into the public grid.

By using the ON / OFF GRID button on the DC BOX controller (part of the DC SET), it is possible to regulate the AC output generated by the DC / AC inverter. If the controller button is in the OFF position, the inverter turns on and converts direct current to alternating current only if any electrical device (connected to the DC BOX controller via potential-free contact) has electrical consumption (relay, contactor, etc. Closes the circuit).

If the production of energy through the panels does not cover the consumption of the entire electrical apparatus, the rest of the necessary energy is supplied to the electrical apparatus from the public grid. When the electric appliance shuts off and water in the tank warms up, the DC BOX controller automatically disconnects the entire system from the PV panels. Therefore the inverter is turned off; it does not generate more AC (alternating current) and thus does not pour any excess energy into the public grid.


Thanks to this patented system and to this configuration (heating of ACS and self-consumption, priority self-consumption) the water tank serves as a 'battery'. The smallest tank is able to accumulate as hot water up to 6 kWh of energy and the largest up to 60 kWh. No excess energy is given to the distribution network, but stored in the form of hot water. This configuration system is today the most profitable option in the market for residential self-consumption facilities.

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