If you are looking for the proper PWM or MPPT charge controller settings for Lithium Iron Phosphate (LiFePO4) Batteries, we recommend taking the following steps:

1. Check if your battery brand and model is included in our Energy Storage Partner program.  If it is, you can click on the Custom Settings Guide, or the BMS Closed Loop Setup Guide if you are using a ReadyBMS with your Morningstar controller.
2. Otherwise, contact your Lithium Iron Phosphate Battery Manufacturer and let them know your  battery model number and any other information concerning your off-grid system such as your charge controller, modules, location, and other system design factors, if known, such as days of battery autonomy, maximum depth of discharge, and how you will monitor your system
3. If your battery brand and model is not included in our Energy Storage Partner program and the battery manufacturer offers insufficient assistance, you can download the Lithium Iron Phosphate Battery Custom Settings doc and access recommended charge and load control profiles

Fortunately, Morningstar has partnered with many lithium battery brands over the years to determine optimal controller settings.  Additionally, Morningstar has engineered special features into select controllers to better support lithium battery charging (e.g. low temperature foldback charging, interactive meters that enable quick and easy charge setting adjustments, alert notifications, and remote monitoring capabilities.

The post Charge Controller Settings for LiFePO4 batteries appeared first on Morningstar Corporation.

Recently, we have received a lot of questions about compliance with the U.S. Trade Agreements Act (TAA) and whether Morningstar products qualify.

The Trade Agreements Act was created to:

1. Approve and implement the trade agreements negotiated under the Trade Act of 1974 [19 U.S.C. 2101 et seq.]
2. Foster the growth and maintenance of an open world trading system
3. Expand opportunities for the commerce of the United States in international trade
4. Improve the rules of international trade and to provide for the enforcement of such rules, and for other purposes.*

TAA compliance means that a product was made in any of the following countries:

• World Trade Organization Government Procurement Agreement Countries
• Free Trade Agreement Countries
• Least Developed Countries
• Caribbean Basin Countries

Please note that TAA compliant countries exclude China, India, Indonesia, Iran, Iraq, Malaysia, Pakistan, Russia, SriLanka, and some others. 

As I write this blog post, Morningstar’s Professional Series and Integrated Series charge controller products are TAA compliant and we don’t anticipate any manufacturing changes in the near future that would alter this. 

Many government agencies, NGO’s and some private sector companies are required to purchase TAA compliant products.  Moreover, many customers and partners associate TAA compliance with ethical and responsible business practices.  If you need such verification, please check the specifications section on our product webpages or contact us.

* 19 USC Ch. 13: TRADE AGREEMENTS ACT OF 1979 (house.gov)

The post What is TAA Compliance and Do Morningstar Products Qualify? appeared first on Morningstar Corporation.

I happened upon this eloquent poem below about connecting a solar charge controller in an off-grid system.  I dare say it touched my soul and I thank you in advance for letting me share it with you:

In the dance of solar power, heed the order keen,
Connect the charge controller first, a vital scene.
For the battery craves its steady, gentle flow,
To nourish its soul and make its energy grow.

Next in line, the PV array, bright and bold,
Its radiant beams, like liquid gold, they hold.
But let not its power rush in haste and flurry,
For patience ensures a harmonious flurry.

Last in line, the loads, they wait with bated breath,
To receive the energy, avoiding any death.
Yet haste not, for the charge controller guards the gate,
In this orderly procession, it dictates fate.

So, in this solar symphony, let caution be your guide,
Connect with care, let wisdom be your pride.
For in the order of connection lies a secret art,
Preserving the charge controller, keeping it smart.

After giving these stanzas some thought and reflection, I offer my impression and interpretation–albeit biased by some of my engineering courses and years of experience in the solar industry.  In essence, these are the key points I believe the poem was trying to convey, if I can cut through its literary rhetoric and explain its message more matter-of-factly:

When installing an off-grid solar system, it is recommended that you connect components in the following order:  

1. Battery to solar charge controller
2. PV array to solar charge controller
3. Electrical load to solar charge controller

And when disconnecting, you reverse that order. The Battery provides power to the controller to turn it on and allow it to function, so always make sure that solar and loads are disconnected before connecting or disconnecting the battery from the controller. This applies to all Morningstar controllers.  Additionally, connections from the battery, load, and array to the charge controller should have disconnect switches and over current protection such as a fuse or DC rated circuit breaker. 

Unfortunately, if an installer does not carefully read their operation manual, they might mistakenly connect the PV array first to the controller.  After making this connection they might be surprised to discover that their charge controller does not turn on.  Worse yet, they might damage the charge controller, even if using the right modules, since the charge controller is not first connected to the battery to power it on and allow its electronics to effectively regulate the power it receives from the array.  

Please remember and spread the word to others to first connect the battery to the solar charge controller when deploying an off-grid system.  

The post Why Doesn’t My Charge Controller Work When I Connect It To My PV Array? appeared first on Morningstar Corporation.

Choosing the right size solar charge controller is a critical step in designing an efficient and reliable off-grid solar power system. By “size” we are referring to the charging current and voltage capacity of the controller.  The size of the solar charge controller you need depends on several factors: 

Solar Array Capacity

This is typically measured in watts (W) or kilowatts (kW) which is a product of the amperage and voltage produced by the array. To determine the size of the solar charge controller, you’ll need to know the total capacity of your solar array. For example, if you have a solar array that delivers a maximum of 20 Amps and a maximum of 100 Volts to your controller you will need a charge controller that specifies the ability to receive these currents and voltages on its datasheet or operation manual. And you will need to compensate for temperature effects.

Battery Bank Voltage

The voltage of your battery bank is another crucial factor. Most off-grid systems use 12-volt, 24-volt, or 48-volt battery banks. Your charge controller needs to be compatible with the voltage of your battery bank. Make sure to match the voltage ratings, because incompatible voltages can cause operation failure with your controller.

Daily Power Consumption of Your Loads

This will help you understand how much energy your solar panels need to generate and how quickly your batteries need to be recharged. Consider all the electrical loads (lights, fans, radio/monitoring equipment, and other devices/appliances you plan to run in your off-grid system and their energy requirements. This information will guide you in sizing your solar array and ultimately your charge controller.

Temperature Considerations

The temperature at your location can affect the performance of your solar panels and, in turn, the charge controller. Most charge controllers are rated based on a specific ambient temperature, often around 25°C (77°F). If you live in an area with extreme temperatures, make sure you have temperature compensation features with your charge controller, which can adjust charging parameters to optimize battery performance in varying temperature conditions.  It is important to calculate your solar array’s voltage output at the lowest recorded temperature where your system is located since solar array voltage output increases at low temperatures.  This voltage must never exceed your controller’s open circuit voltage (Voc), otherwise you may destroy your controller and create a fire hazard.

Efficiency of the Charge Controller

The efficiency of the charge controller is another factor to consider. Charge controllers are not 100% efficient, and some power is lost as heat during the charging process. To compensate for this, you may need to oversize your charge controller slightly. For example, if your solar panel array generates 2 kW, you might choose a 2.5 kW charge controller to ensure that enough power is delivered to your batteries when you factor in inefficiencies, intermittent clouds and low sun angles of incidence.

Future Expansion

Consider your future plans for expanding your off-grid system. If you anticipate adding more solar panels or increasing your battery bank’s capacity, it’s a good idea to choose a charge controller with some room for growth. This will save you the hassle and cost of replacing the controller when you decide to expand your system.

Controller Type

There are two main types of solar charge controllers.

1. PWM (Pulse-Width Modulation) controllers:
   – Operate at battery voltage which is generally below the maximum power voltage (Vmp)
   – Are suitable for small module configurations
   – Are often chosen for very hot climate which will not yield as much MPPT boost
   – Are less expensive than MPPT controllers
2. MPPT (Maximum Power Point Tracking)  controllers:
   – Convert excess input voltage into amperage
   – Operate at maximum power voltage (Vmp)
   – Are suitable for large module configurations that have a lower cost per watt
   – Provide more boost than PWM, especially during cold days and/or when the battery voltage is low

MPPT controllers use newer technology that supports more module types (e.g. 30 and 60 cells in addition to 72 cells), and they support array oversizing.  Your choice between MPPT and PWM controllers depends on your budget and specific system requirements.

To ensure proper charge controller selection and the long-term performance and reliability of your off-grid system, it’s helpful to consult with a knowledgeable solar installer or engineer who can help you make the best choice based on your specific needs and circumstances. Some solar distributors can size your solar charge controller and your entire off-grid system for that matter.  Moreover there are string sizing calculator tools that can help you determine if your controller and other components will meet requirements for your system.  By taking these factors into account, you are well on your way to designing an off-grid solar power system that meets your energy needs while maximizing the lifespan of your batteries and equipment.

The post What Size Solar Charge Controller Do You Need? appeared first on Morningstar Corporation.

While battery voltage has been used for many years to approximate a battery’s state of charge, we recently produced and launched a ReadyShunt Block Kit that is used with the GenStar MPPT to more precisely calculate a battery’s state of charge as a percentage from 0 to 100%.  The ReadyShunt Block Kit includes a ReadyBlock that snaps into the GenStar MPPT, and a shunt that is connected into a system’s positive or negative wire.  SOC values are calculated natively within the controller.  No external battery meter or external 3rd party shunts required, greatly simplifying the system.  Accurate SOC measurements:

• Ensure your battery undergoes a complete charge at regular intervals to prolong battery life and ensure maximum usable capacity
• Enable better system level control and logic automation for your site concerning generator starts/stops, load shedding and excess energy diversion
• Are important for recording long term trends of battery charge levels to ensure proper system cycling and expected depth of discharge
• Provide highly accurate absorption charge stage control based on final tail current
• Incorporate charge and discharge currents from the charge controller as well as external charging from additional sources. (generator, fuel cell, wind, etc)
• And battery amp-hour values are available via Morningstar’s communication protocols allowing them to be viewed with the Mobile App, LiveView Web Interface, and MODBUS protocols

Applications that can benefit from this SOC calculation include telecom, oil & gas, security/monitoring, lighting, residential, RV-caravan, marine and others.  And especially those applications deploying lead acid batteries that don’t have battery management systems that calculate SOC. The ReadyShunt can be connected to the GenStar MPPT and any future Morningstar product that is equipped with a ReadyRail.

The post ReadyShunt Enables Accurate Battery State of Charge (SOC) Measurements appeared first on Morningstar Corporation.

• Battery sulfation at the internal lead plates
• Low battery state of charge
• System downtime due to insufficient charging
• A significant reduction in overall battery operating life
• A decrease in overall storage capacity

In order to optimize battery health and performance it is recommended to contact your battery manufacturer and have them provide you with the precise recommended absorption, float, and equalization voltage including duration, and interval parameters that you can set for your charge controller. These parameters will vary depending on the battery brand, type and chemistry (e.g. sealed, gel, flooded lead acid, lithium, etc.).  As an example, for a given battery, a manufacturer might recommend:

• absorption charge at 14.1V for 3 hours
• float charge at 13.7V for 2 hours
• equalization charge at 14.9V for 2 hours once per month
  (note: this is an example and equalization is not recommended for some batteries)

It is not uncommon for batteries to last only a couple of years if charge controller settings are not set to battery manufacturer specifications.  But, by following battery manufacturer recommended setpoints, some batteries can often last for 5 to 10 years or more.  Since batteries are often the most expensive component of your off-grid system (representing 40% of initial costs and up to 80% of lifetime costs), adjusting charge settings is extremely important.  Proper charge controller settings not only reduce lifetime battery costs, it also reduces the time and money you spend to replace the batteries and the costs associated with system downtime. Installers and consumers can find recommended charge settings on battery manufacturer websites, operation manuals, or by contacting them directly. 

Controllers with interactive input displays

Metered versions of ProStar (Gen3) PWM and ProStar MPPT controllers, and the new GenStar MPPT controllers have interactive input displays with scroll buttons that allow for adjustments to absorption, float and equalization parameters within seconds directly at the controller, with no additional data connection needed.  The key words are “interactive input” since some meters on TriStar controllers for example, only allow “read only”  interaction, but  not interactive input and adjustment of charge settings.  In order to use the controller’s interactive meter to adjust the setpoints, you should ensure that DIP switches 4, 5, and 6 are in the ON position (indicating a custom setting), otherwise your meter screen will not display options for adjusting absorption, float or equalization charge settings.  

Controllers without interactive meters

Morningstar controllers without interactive input meters, such as TriStar PWMs, TriStar MPPTs, non-metered ProStar PWMs and ProStar MPPTs, and SunSaver MPPT’s can use a PC and our free MSView software to adjust and program charge settings. See the MSView page for more info.  If you would rather not use MSView, you can consult the solar controller’s operation manual to find DIP Switch settings that will establish a preset that most closely matches the recommended setting for your battery.  Please note that a preset that is labeled and generally used for Sealed batteries can be used for other battery types, if the particular battery type’s recommended settings most closely match the labeled preset.  It’s the numerical settings that are most important, not the labels.

Controllers with Battery Select Jumpers

Morningstar’s SunSaver PWM and SunLight PWM controllers have battery select jumpers.  When inserted they set absorption voltages lower than when removed. The Battery Select Jumper is typically inserted for sealed batteries.  Moreover, when jumpers are removed, this creates a higher absorption setpoint voltage and it also enables an  equalization charge.

Other factors

Other environmental factors can impact controller charge settings.  Batteries that are located in off-grid applications that are exposed to cold temperatures for long periods of time might require higher voltage settings, whereas hot temperature exposure might require lower voltages.  Fortunately, many Morningstar controllers have built-in temperature compensation and others can use a remote temperature sensor to account for the effects of temperature.  

Load consumption and battery depth of discharge are also factors.  Systems that experience consistent small load consumption and low battery depth of discharge throughout the year generally require lower voltage settings than systems that experience inconsistent load consumption or greater depth of discharge.  While there might be some differences of opinion on optimal charge settings for a given system, these differences are small when compared to doing nothing at all.

The post Adjusting Charge Controller Settings to Battery Manufacturer Recommendations appeared first on Morningstar Corporation.

Because of this forward-thinking approach, our long-established , TriStar MPPT, ProStar MPPT, SunSaver MPPT, TriStar-PWM, and ProStar Gen3 controllers are extremely well-suited to work with the latest l lithium batteries with programming we provide for that application.  Furthermore, our new GenStar MPPT is an industry game-changer, with plug-in ReadyRail technology that lets a user seamlessly add a lithium ReadyBMS block to the controller for two-way communications and control.

Both the custom programming with our current line, and the new ReadyBMS capability with our new GenStar MPPT line, are part of our Energy Storage Partner (ESP) program.   Encompassing over 20 of the leading lithium battery manufacturers, ESP provides the customized profile settings needed for seamless lithium integration into a new or existing project.  In addition, several of the leading lithium brands in that program achieve 2-way communication and even closed-loop operation with a ReadyBMS used with our new GenStar MPPT controller.   With either solution, using a lithium battery from our ESP program will result in a higher success rate when programming your controller.

Ultimately your battery manufacturer knows what’s best for their specific battery. If your battery is not on our ESP list, we strongly recommend you speak with your battery manufacturer to discuss their recommended charge settings and be sure to let them know you are using a solar charge controller. It’s helpful to review your controller’s Set Up Wizard in MSView or better yet, have the wizard open during your discussion to be sure to get all the information needed for the custom programming.

If your lithium battery bank has a battery management system (BMS) it must not be allowed to break the connection between the controller and the battery. The controller will not operate properly without the battery connected and can cause damage if the disconnect occurs while solar charging. The BMS can be prevented from disconnecting due to high battery voltage by setting the controller Absorption and HVD threshold slightly below the BMS High Voltage Cutoff threshold. Additionally, the controller will need to be custom programmed to disable equalization, disable temperature compensation and possibly limit the absorption and float stages.

For more information, please see our technical documents regarding lithium and other battery types:

https://www.morningstarcorp.com/lithium-batteries/

http://www.morningstarcorp.com/morningstar-best-practices-battery-chemistry/

The post Tech Tip: Custom Programming for Lithium Batteries appeared first on Morningstar Corporation.

A couple of basic principles that form the foundation of system sizing are:

1. Array to Load Ratio (ALR): a ratio of the net daily amp-hours from the solar array, stored in the battery bank compared to the net daily amp-hours consumed by the load(s).
2. Days of Battery Autonomy: the number of days the fully charged batteries can power the loads without being recharged and without exceeding their recommended depth of discharge (DOD)

For a reliable system, experience has shown that the average daily amp-hours delivered to the battery bank, after factoring in all the system losses, needs to be at least 115% to 120% of the daily amp-hours consumed by the load(s). This is an ALR of 1.15 to 1.20. This minimum ALR needs to be met for the worst solar/weather month that the system is expected to operate, typically December or January in the northern hemisphere.

Why a minimum ALR of 1.15 to 1.20 you might ask?  Well, if the array only delivered the same amount of amp-hours per day as the load consumed (an ALR of 1.00), and the battery bank discharged due to several days of bad weather, there would not be any excess charging current available to refill the battery bank. This excess 15%-20% charging capability allows the battery to recover (recharge fully) after such occurrences.

Factors affecting the net solar energy harvested by a system include solar availability and weather, shading, array orientation, proper component selection, and various system efficiencies.

Net solar resources are the most significant factor to energy harvest, and they vary from location-to-location and month-to-month. There are multiple databases and solar calculators available online; many of them are based on the NREL database (see https://pvwatts.nrel.gov/). They can be used to determine the solar resource, on a month-by-month basis and at various tilt angles, for many locations. For most stand-alone off-grid systems the tilt angle is based on the optimal tilt angle that provides the greatest solar energy harvest during the worst month of operations. Designing to the month with the lowest solar energy potential will result in a larger solar array and excess energy production for the remainder of the year. For larger systems, and those with critical loads, a generator is often used to supplement the winter power generation. This allows for a smaller solar array with the generator making up the mid-winter shortfall of energy production.

Shading on the solar array can profoundly reduce the power and energy produced. Ideally there should be no shading on the solar array from about 9AM to at least 3PM. If there is unavoidable shading, then the size of the solar array may need to be increased appropriately. Remember, snow accumulation on the solar array is a form of shading and must be considered.

Ambient temperature affects the solar module’s performance and therefore energy production. Typically, higher temperatures decrease module performance, and colder temperatures increase module performance.

Matching the system components can also affect system performance. For PWM-type solar charge controllers, the output voltage of the solar array must be properly matched with the charge controller and battery bank’s nominal voltage. Mis-matched voltages can significantly reduce the net power harvested and may damage the PWM controller. MPPT-type controllers can both harvest more power from the solar array and compensate for most mismatches between the solar output voltage and the battery voltage.

System inefficiencies can reduce the net solar array performance by 8%-10%.  These inefficiencies include:

• Module performance mismatch due to production tolerances, typically about 2-3% losses.
• Wiring losses due to wire resistance and physical connections, typically about 2-3% total.
• Soiling and dirt on the module face, typically about 2-4%.
• Ageing of the solar modules. Solar modules lose about 0.5% to 1% of output power per year of service. Factoring in some module aging is prudent for long system reliability.

Moreover, charging a battery bank is not 100% efficient. The net charge efficiency is only about 85% to 90%.  This charge efficiency decreases further as the battery ages. So, typically the net amp-hours stored in the battery bank are about 20% less than the theoretical production of the solar array. Thus, the solar array needs to be sized about 20% larger than it might first appear. This 20% increase is on top of the 115%-120% ALR.

The battery bank is the “gas tank” of the system. It not only powers the load(s) through the night, but also bridges periods of bad weather, where there is minimal solar resource available. For many locations, 4 to 5 days of Battery Autonomy is considered adequate. For locations with significant weather issues, 7 to 10 days, or more, of battery autonomy may be required. Factors that affect battery autonomy include: the size, age, and health of the battery bank, ambient temperature, discharge rate, average and maximum DOD.  With the addition of a generator or other supplemental charging source, the size of the battery bank can be greatly reduced, often down to 2 or 3 days of Battery Autonomy.

Applying the concepts in this post and designing for adequate ALR and battery autonomy will help ensure your system runs reliably for many years.

The post Tech Tip: Basic System Sizing Design Concepts appeared first on Morningstar Corporation.

During our April Controllers & Inverters Overview webinar, one of the attendees asked “How often do Morningstar MPPT controllers evaluate and determine the maximum power point on the IV curve that the controller should operate at?” Below is the answer to that question:

Morningstar MPPT controllers evaluate the maximum power point (also referred to as “sweeping the IV curve”) at 3 minute intervals.  The controller does this by slightly altering its resistance and subsequently calculating the product of the resulting amperage and voltage.  Morningstar’s TrakStar technology evaluates and determines the maximum power point in a fraction of a second, which is extremely fast compared to competitor MPPT technologies.  The evaluation is so fast that any disruptions with power input to charge batteries are negligible, as opposed to the power losses that some competitor MPPT controllers incur during sweeping.

Moreover, it is important to note that Morningstar’s TrakStar technology evaluates ALL the points on the IV curve when it performs a sweep, not just points near the previously determined power point.  This ensures that the true maximum power point is established in cases where multiple high points exist on the IV curve.

In order to get the best results from your MPPT controller it is recommended that all the modules that make up your solar array are uniform (e.g. the same brand and model number). Otherwise, if your array is composed of different model types and specifications, this can confuse the MPPT controller’s tracking algorithm. Other factors that can disrupt PV array performance and power point tracking include inadvertent shading, and dust and debris on the modules.

The post How often do controllers evaluate and determine the maximum power point? appeared first on Morningstar Corporation.