Solar Charge Controllers and Regulators
How do they work
What is the function of a Solar Charge Regulator?
The main function of a controller or regulator is to fully charge a battery without permitting overcharge and at the same time preventing reverse current flow at night. Simple controllers contain a transistor that shunts the PV charging circuit, terminating the charge at a pre-set high voltage and, once a pre-set reconnect is reached, opens the shunt, allowing charging to resume. More sophisticated controllers utilize pulse width modulation (PWM) or maximum power point tracking (MPPT) to assure the battery is being fully charged. The first 70% to 80% of battery capacity is easily replaced, but the last 20% to 30% requires more attention and therefore more complexity.
How do solar regulators work?
The electronic circuitry in a controller monitors the voltage of the connected battery and determines the state of charge of the battery. As the battery nears full charge the amount of current flowing to the battery is reduced until the battyer reaches its full state of charge. Features to watch out for with controllers are:
- Low-voltage load disconnect (LVD) – reduces damage to batteries by preventing deep discharging.
- Reverse current leakage protection – disconnects the array to prevent feedback into the solar modules at night.
- System monitoring - analogue or digital display meters, indicator lights and/or warning alarms.
- Over current protection – achieved with fuses and/or circuit breakers.
- Mounting options – flush mounted, wall mounted, indoor or outdoor enclosures for all weathers.
- System control – control of other components in the system; standby generator or auxiliary charging system, diverting array power once batteries are charged, transfer to secondary batteries.
- Load control – automatic control of secondary loads, or control of lights, water pumps or other loads with timers or switches
- Temperature compensation – utilized whenever batteries are placed in a non-climate controlled space. The charging voltage is adjusted to the corresponding temperature.
- Pulse Width Modulation (PWM) – an efficient charging method that maintains a battery at its maximum state of charge and minimizes build-up of sulphur by pulsing the battery voltage at a high frequency.
- Maximum Power Point Tracking (MPPT) – a new charging method designed to extract the most power possible out of a solar module by altering its operating voltage to maximize the power output.
How to size a solar regulator?
Q. Do I need to fit a regulator?
A. Yes. It is recommended a regulator is fitted if the minimum ratio of 10W of solar panel to 100Ah battery capacity is exceeded.
A. Yes. It is recommended a regulator is fitted if the minimum ratio of 10W of solar panel to 100Ah battery capacity is exceeded.
Q. How do I calculate the Amp rating of the regulator needed?
A. Employ the physics equation of Amps x Volts = Watts P= V x I. Power (Watts) = Voltage (V) x Amps (I).
A. Employ the physics equation of Amps x Volts = Watts P= V x I. Power (Watts) = Voltage (V) x Amps (I).
Charge controllers are rated and sized according to the solar array system voltage and current. The most common solar array system voltages are 12, 24 and 48 volt and controllers are rated accordingly. Controller operating voltages vary from 6 - 60 volts and from 1 - 60 amps. For example, if you have 2 x 85W, 12V solar panels and one module produces 5.34 amps, your combined (2 panel) system will produce 10.68 amps at 12 volts. Because the current of a solar panel varies with temperature, light reflection and other factors could lead to sporadic increased current levels. Because of this the operating current of a controller is increased by at least 25%. This means that in our example the controller must be able to accommodate at least 13.35 amps. A 15 amp or greater, rated solar controller would be used to handle the current flow from our example. NOTE: it makes sense to allow for additional capacity to be added to your system and would therefore make sense to select either a 20A or 30A solar controller.
Q. What is state of charge and how is it measured?
Take for example the performance of Steca products. They are shown by the accuracy of the state of charge (SOC) measurement, which results in the long lifetime of the battery.
Take for example the performance of Steca products. They are shown by the accuracy of the state of charge (SOC) measurement, which results in the long lifetime of the battery.
Q. What does SOC mean?
The SOC (State of Charge) indicates the actual charging status of the battery. If the battery is fully charged the SOC is 100 % - if it is completely empty the SOC is 0 %. All values in between are possible, but a lot of battery types should not reach SOC values less than 30 %. It is important not to confuse the SOC with the capacity of the battery. The SOC does not reflect the remaining capacity of the battery. The actual remaining capacity of the battery is influenced by a lot of parameters besides the SOC. Multiplying the SOC with the nominal capacity of the battery results in information about the residual capacity of the battery. This value does still not reflect the remaining capacity accurately due to various other parameters including the age of the battery.
The SOC (State of Charge) indicates the actual charging status of the battery. If the battery is fully charged the SOC is 100 % - if it is completely empty the SOC is 0 %. All values in between are possible, but a lot of battery types should not reach SOC values less than 30 %. It is important not to confuse the SOC with the capacity of the battery. The SOC does not reflect the remaining capacity of the battery. The actual remaining capacity of the battery is influenced by a lot of parameters besides the SOC. Multiplying the SOC with the nominal capacity of the battery results in information about the residual capacity of the battery. This value does still not reflect the remaining capacity accurately due to various other parameters including the age of the battery.
Q. Why is SOC calculation important?
If a battery is charged, the charge controller needs to know if it is full to prevent a batteries damage due to over charging. While discharging, the controller needs to know if the battery is empty in order to prevent dangerous deep discharging. There are several possibilities to determine if the battery is full or empty. The most common criterion is the voltage of the battery. A certain fixed voltage is set to disconnect the load and protect the battery. Unfortunately this criterion is improper. Especially in solar systems, low discharging currents are common and lead to improper battery maintenance if a fixed voltage for load disconnection is used. Better solutions also take the charging / discharging current into account to determine if the battery has to be disconnected from the load. But also this method does not allow an adequate load disconnection to protect the battery optimally due to a very low accuracy and a high error rate. A lot of additional parameters, like temperature, the age of the battery, the user behaviour and other values, influence the battery.
Only an accurately calculated state of charge allows to disconnect the load correct according to the properties of the battery. This is why Steca developed a powerful and precise algorithm to determine the actual state of charge of a battery.
If a battery is charged, the charge controller needs to know if it is full to prevent a batteries damage due to over charging. While discharging, the controller needs to know if the battery is empty in order to prevent dangerous deep discharging. There are several possibilities to determine if the battery is full or empty. The most common criterion is the voltage of the battery. A certain fixed voltage is set to disconnect the load and protect the battery. Unfortunately this criterion is improper. Especially in solar systems, low discharging currents are common and lead to improper battery maintenance if a fixed voltage for load disconnection is used. Better solutions also take the charging / discharging current into account to determine if the battery has to be disconnected from the load. But also this method does not allow an adequate load disconnection to protect the battery optimally due to a very low accuracy and a high error rate. A lot of additional parameters, like temperature, the age of the battery, the user behaviour and other values, influence the battery.
Only an accurately calculated state of charge allows to disconnect the load correct according to the properties of the battery. This is why Steca developed a powerful and precise algorithm to determine the actual state of charge of a battery.
Q. How does the Steca SOC algorithm work?
The Steca state of charge algorithm is a combination of different methods in order to ensure a precise calculation combined with a stable long time performance. Cost optimised product realisation is additionally another important point for Steca. Years of experience in this field and important research activities led to a self learning „fuzzy logic“ algorithm. It takes into account the user behaviour and the ageing of the battery. The voltage of the battery, as well as all battery currents, are watched closely by the charge controller in combination with the temperature. The charger approximates the SOC, during a learning period which takes place in the first cycles. By monitoring the battery and adapting parameters to the changes, a self learning algorithm results that is also able to take the use of the battery into account. This characteristic makes the Steca SOC algorithm a powerful and reliable function, which will ensure the correct monitoring of the battery. The user benefits from a fast and precise information about the battery status that is displayed on the charge controller. Finally the user benefits from the most important advantage to enlarge the life-time of the battery with the help of an optimised battery maintenance.
The Steca state of charge algorithm is a combination of different methods in order to ensure a precise calculation combined with a stable long time performance. Cost optimised product realisation is additionally another important point for Steca. Years of experience in this field and important research activities led to a self learning „fuzzy logic“ algorithm. It takes into account the user behaviour and the ageing of the battery. The voltage of the battery, as well as all battery currents, are watched closely by the charge controller in combination with the temperature. The charger approximates the SOC, during a learning period which takes place in the first cycles. By monitoring the battery and adapting parameters to the changes, a self learning algorithm results that is also able to take the use of the battery into account. This characteristic makes the Steca SOC algorithm a powerful and reliable function, which will ensure the correct monitoring of the battery. The user benefits from a fast and precise information about the battery status that is displayed on the charge controller. Finally the user benefits from the most important advantage to enlarge the life-time of the battery with the help of an optimised battery maintenance.
Q. Which chargers from Steca carry the optimised algorithm?
The Steca product range is divided into two lines. One is optimised for use in simple applications with less demand and equipped with the minimum necessary features. The other line is designed to cover high-end demand to supply a good communication interface to the user and optimised battery maintenance features. For both lines there exist charge controllers in a wide power range. Charge controllers in a wide power range exist for both lines. All chargers that are equipped with the special Steca State of Charge algorithm are marked with the SOC symbol in this catalogue.
The Steca product range is divided into two lines. One is optimised for use in simple applications with less demand and equipped with the minimum necessary features. The other line is designed to cover high-end demand to supply a good communication interface to the user and optimised battery maintenance features. For both lines there exist charge controllers in a wide power range. Charge controllers in a wide power range exist for both lines. All chargers that are equipped with the special Steca State of Charge algorithm are marked with the SOC symbol in this catalogue.
State of Charge Example
The graph shows the properties of a 28 Ah lead acid battery in relation to the charging / discharging current, the voltage and the state of charge. If the full battery is discharged with 50 A and a load cut off voltage of 1.85 V/cell is applied (equal to 11.1 V for 12 V battery) the load will be disconnected at around 70 % state of charge. This means the battery is still quite full but the load can no longer be supplied due to deep discharging protection. If it is discharged with 5 A, the voltage of 11.1 V will lead to a disconnection at 10 % state of charge which is already a dangerous deep discharge for the battery. With the Steca SOC algorithm the load will be disconnected along the line of 30 % SOC in dependence of the discharging current at the cross with the discharging current line. Only this complicated procedure can ensure optimal battery maintenance.
Q. How is a regulator used in a home solar system?
System Overview
A Solar Home System consists of a Steca Solar charge controller, a battery, a solar module and the load. The load is always a DC load in standard Solar Home Systems. The charge controller is connected directly to the battery. The module and the load are connected directly to the charge controller terminals. Steca controllers regulate the complete energy flow within the system. The battery is charged by the current from the solar module. If the battery is full, the charge controller limits the current to the battery to protect the battery from over charging. If the load discharges the battery, the controller also cuts off the load before the battery is empty, in order to prevent a dangerous deep discharge of the battery. Steca controllers also have an integrated intelligent battery monitoring system. The optimal charging strategy will be chosen depending on the need of the battery. In Solar Home Systems the charge controller is the central device – all functions of the system are influenced by this controller. Due to this fact it is important to choose a good controller.
System Overview
A Solar Home System consists of a Steca Solar charge controller, a battery, a solar module and the load. The load is always a DC load in standard Solar Home Systems. The charge controller is connected directly to the battery. The module and the load are connected directly to the charge controller terminals. Steca controllers regulate the complete energy flow within the system. The battery is charged by the current from the solar module. If the battery is full, the charge controller limits the current to the battery to protect the battery from over charging. If the load discharges the battery, the controller also cuts off the load before the battery is empty, in order to prevent a dangerous deep discharge of the battery. Steca controllers also have an integrated intelligent battery monitoring system. The optimal charging strategy will be chosen depending on the need of the battery. In Solar Home Systems the charge controller is the central device – all functions of the system are influenced by this controller. Due to this fact it is important to choose a good controller.
Q. How is a regulator used in a stand alone inverter system?
System Overview
Stand alone inverter systems consist of a standard Solar Home System with solar module, battery and solar charge controller, plus an additional inverter that supplies AC power. To such a system you can connect any commercial AC appliance known from the public grid. Furthermore, it is even possible to run DC loads. The inverter is connected directly to the battery with a short and thick cable. Such a system can be realised as a standard 12 V system, alternatively also as a 24 V or 48 V system for higher power demands. Due to the simple system concept, the installation is fast and easy to do.
System Overview
Stand alone inverter systems consist of a standard Solar Home System with solar module, battery and solar charge controller, plus an additional inverter that supplies AC power. To such a system you can connect any commercial AC appliance known from the public grid. Furthermore, it is even possible to run DC loads. The inverter is connected directly to the battery with a short and thick cable. Such a system can be realised as a standard 12 V system, alternatively also as a 24 V or 48 V system for higher power demands. Due to the simple system concept, the installation is fast and easy to do.
Q. How are regulators used in solar/wind hybrid systems?
System overview
The main feature of a hybrid system is the use of two or more different energy sources. For so-called photovoltaic hybrid systems in the field of solar energy especially a diesel generator, a wind generator or a public grid is used as an additional source of energy. The inverters with integrated battery charger designed for hybrid systems supply the connected alternating current loads either out of the battery or from the second energy source – always according to the requirements of the system. It is also possible to recharge the battery from the additional energy source via the battery charger. The advantage of photovoltaic hybrid systems is that the solar generator does not have to be oversized to supply the loads even during months with low solar irradiation. This saves a significant amount of the initial investment. The solar produced power is always used primarily in the system. But in combination with the second energy source reliable AC power is available day and night throughout the year.
System overview
The main feature of a hybrid system is the use of two or more different energy sources. For so-called photovoltaic hybrid systems in the field of solar energy especially a diesel generator, a wind generator or a public grid is used as an additional source of energy. The inverters with integrated battery charger designed for hybrid systems supply the connected alternating current loads either out of the battery or from the second energy source – always according to the requirements of the system. It is also possible to recharge the battery from the additional energy source via the battery charger. The advantage of photovoltaic hybrid systems is that the solar generator does not have to be oversized to supply the loads even during months with low solar irradiation. This saves a significant amount of the initial investment. The solar produced power is always used primarily in the system. But in combination with the second energy source reliable AC power is available day and night throughout the year.
Q: What are Pulse Width Modulation (PWM) Solar Regulators?
Charging a battery with a solar pv system is difficult. In the early days regulators were just on-off switches that tried to prevent the plates of the battery being destroyed, a process known as sulphation, that occurred when solar panels produced excess energy that hand to be handled correctly. As solar pv systems came to maturity it was clear that a radical rethink was need on how these primitive regulators could cope with demands for better charging. PWM has recently surfaced as the first significant advance in solar battery charging.
Charging a battery with a solar pv system is difficult. In the early days regulators were just on-off switches that tried to prevent the plates of the battery being destroyed, a process known as sulphation, that occurred when solar panels produced excess energy that hand to be handled correctly. As solar pv systems came to maturity it was clear that a radical rethink was need on how these primitive regulators could cope with demands for better charging. PWM has recently surfaced as the first significant advance in solar battery charging.
PWM solar chargers use technology similar to other modern high quality battery chargers. When a battery voltage reaches the regulation set-point, the PWM algorithm slowly reduces the charging current to avoid heating and gassing of the battery, yet the charging continues to return the maximum amount of energy to the battery in the shortest time. The result is a higher charging efficiency, rapid recharging, and a healthy battery at full capacity.
In addition, this new method of solar battery charging promises some very interesting and unique benefits from the PWM pulsing. These include:
- Ability to recover lost battery capacity and de-sulphate a battery
- Dramatically increase the charge acceptance of the battery
- Maintain high average battery capacities (90% to 95%) compared to on-off regulated state-of-charge levels that are typically 55% to 60%
- Equalize drifting battery cells
- Reduce battery heating and gassing
- Automatically adjust for battery aging
- Self-regulate for voltage drops and temperature effects in solar systems
Q. Why is this technology important to me?
There are substantial benefits of using PWM technology in a solar pv energy system. The benefits include:
There are substantial benefits of using PWM technology in a solar pv energy system. The benefits include:
Longer battery life:
- reducing the costs of the solar system
- reducing battery disposal problems
More battery reserve capacity:
- increasing the reliability of the solar system
- reducing load disconnects
- opportunity to reduce battery size to lower the system cost
Greater use of the solar array energy:
- get 20% to 30% more energy from your solar panels for charging stop wasting the solar energy when the battery is only 50% charged opportunity to reduce the size of the solar array to save cost.
Greater user satisfaction:
- get more power when you need it for less money!!
(Information courtesy of Morningstar Corporation)
OUTBACK (MPPT) CONTROLLER
The OutBack MX60 Maximum Power Point Tracking (MPPT) charge controller enables your PV system to achieve its very best performance. Rated for up to 60 amps of DC output current, the MX60 can be used with battery systems from 12 to 60V DC with PV open circuit voltage as high as 140V DC. The MX60 has fully adjustable set points that allows it to work with virtually any battery type, chemistry and charging profile. The MX60 allows you to use a higher output voltage PV array with a lower voltage battery. This is important as it reduces battery wire size and power loss from the PV array to the battery or inverter location and thereby maximizes the performance of your PV system. The MX60 comes standard with an easy to use and understand display of the PV system’s performance. The four line, 80 character, back-lit LCD display is also used for programming and monitoring of the system’s operation, including built-in data logging with 64 days of memory. The MX60 can also be connected to the OutBack MATE system controller and display to allow monitoring of up to eight MX60 controllers from a location up to 1000 feet away. The MATE also includes an opto-isolated RS232 port for connection to a PC for data logging and system monitoring.
Fox Solar Charge Controllers from SunWare
Fox Solar Regulators provide 3 stage charging to your battery bank from solar panels with a rated power of up to 20Amps. They are equally ideal on board yachts, for use in the home and on professional installations providing both overcharge and deep discharge protection for deep cycle batteries. The range of Fox solar regulators are conveniently available in four versions, specifically tailored to the requirements of leisure charging applications.
Fox Charge Controllers
Fox 250 12V Single Battery Models.
Ideal for battery banks on board motor homes, caravans & yachts where a single battery bank (one or more batteries in parallel) requires charging. Choose either the simple to mount Surface version, only 2 fixing screws required or the recessed version for a built in finish.
Ideal for battery banks on board motor homes, caravans & yachts where a single battery bank (one or more batteries in parallel) requires charging. Choose either the simple to mount Surface version, only 2 fixing screws required or the recessed version for a built in finish.
Fox 350 12/24V Dual Battery Models
The Fox 350 includes all the standard features with additional detailed information on the LCD display including battery state of charge percentage. This unit is ideal where 2 battery banks are installed and typically both require top up, particularly whilst unattended. The system’s built in logic charges battery 1 first and ensures it has remained at the final level of 3 stage charging for 1 hour before changing over to battery bank 2. There’s also even an emergency charge function that activates charge to battery 2 if it falls below 10.8V providing battery 1 has more than 11.5V.
The Fox 350 includes all the standard features with additional detailed information on the LCD display including battery state of charge percentage. This unit is ideal where 2 battery banks are installed and typically both require top up, particularly whilst unattended. The system’s built in logic charges battery 1 first and ensures it has remained at the final level of 3 stage charging for 1 hour before changing over to battery bank 2. There’s also even an emergency charge function that activates charge to battery 2 if it falls below 10.8V providing battery 1 has more than 11.5V.
Fox Remote Display
A discreet digital display unit for remote installation from a regulator enabling the user to view information at a secondary location. Max distance from regulator is 3M. Available in surface, Fox D/1 and recessed Fox D/1E models.
A discreet digital display unit for remote installation from a regulator enabling the user to view information at a secondary location. Max distance from regulator is 3M. Available in surface, Fox D/1 and recessed Fox D/1E models.
Fox 250 and 350 models include the following features:
- Digital display of charge and load currents, Volts and warnings
- Soft touch keypad to scroll through display and program settings
- Latest pulse width modulation technology with built in temperature compensation to ensure the most efficient battery charging
- Manual switch for controlling loads on and off
- Reverse polarity protected and 2 year warranty
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ALL OUR PRICES INCLUDE VAT
CARRIAGE COSTS DEPEND ON WEIGHT. CALL US TO DISCUSS
YOUR REQUIREMENTS
CALL US NOW ON 0208 916 2400
FOR PRICING AND FURTHER INFORMATIO
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