I’d like to know if I can change the strategy of model. For example, in my model, when the SOC is about 40% the Fuel Cell starts to run, to feed the load. But, in our pilot project, the FC starts to run when the bus dc voltage goes down of 48Vdc. Moreover, in the other words, when the PV system doesn’t serve the load, because it doesn’t have enough

How is battery depletion calculated? The battery depletion is the difference between the battery's state of charge (SOC) at the start of the year and the SOC at the end of the year. The SOC at the start of the year is specified in the battery component window under the title "Initial state of charge (%)". The difference occurs because HOMER s

Say you have a battery with a round-trip efficiency of 80%. HOMER assumes the charge efficiency is equal to the discharge efficiency, meaning they are both equal to the square root of 80%, which is 0.894. So if you put 100 kWh of DC electricity into the battery (assuming it could absorb it all) then the energy level in the battery would increase

Is the needed voltage output important for the simulation? HOMER does not model the voltage of the DC bus, so you don't need to specify the bus voltage. However, you should take the DC bus voltage into account when specifying the quantities of batteries to consider. For example, if you are using a 6V battery and you choose a 24V bus voltage,

The Smart Energy 25 is a 25 kWh, 100 kW carbon fiber flywheel. It is an AC device, but HOMER will connect it to the DC bus because it cannot model AC electrical storage. To model this flywheel in HOMER, you should add a converter, but make it free, 100% efficient, and larger than the aggregate capacity of the largest number of flywheels that you ar

When charging the batteries with a genset, does HOMER conduct a bulk charge followed by an adsorb charge? Does it account for the different battery types? HOMER doesn't model different phases of battery charging such as bulk and adsorb. But it will taper the amount of power going into the battery bank as it approaches full charge. Each time

I want to input a battery system with 2 parallel strings of 12 2V batteries in series , ie 24 2 V batteries with a system voltage of 48V. If I input 24 quantity of batteries, 12 batteries per string and 2 strings it gives me 24V system voltage – it should be 48V ? To get 48V I have to input 24 batteries per string. What am I doing wrong? A s

HOMER does not model the battery charge controller as a separate component. So you must include its cost and efficiency in the values you specify for other components. If you are simulating a PV-battery system or a grid-connected PV system, the best place to include the charge controller costs and efficiency is the PV aray inputs. In the cost of t

Is there any way we can separate the charge controller out from the "converter"? HOMER does not let you model the charge controller explicitly, so you have to combine it either with the converter or the battery. It is also not possible to model a system without an MPPT. The presence of the MPPT allows us to ignore the DC bus voltage, and thereb

Regarding AC wind turbines, if the turbine's voltage does not match that of the load, a transformer would be necessary, and the turbine power curve should be adjusted to show the useable power output (the power output from the transformer) versus wind speed. It seems unlikely that someone would install a 50 Hz wind turbine to serve a 60 Hz load, b

What is meant by a 'battery competition'? How do I set one up? You can add up to ten battery components to a HOMER model. HOMER will only simulate systems with one type of battery at a time. HOMER will model all the possible sizes of type one, all the possible sizes of type two, and so on. It will rank the results by life cycle cost as it alw

The Advanced Storage Module unlocks HOMER's Modified Kinetic Battery Model. There are two batteries built-in to the HOMER library that use the Modified Kinetic Battery Model. You can identify these batteries by the text "[ASM]" appended to the name. If you don't have the Advanced Storage Module, you can't add these batteries to your model, and you

I want to add my own battery Let's start with the capacity curve. HOMER uses the capacity curve to calculate the kinetic battery model constants, the most important of which is the "maximum capacity", which is essentially the y-intercept of the curve. In our experience, the c and k values, which relate to the shape of the curve, have surprisi

Using the flywheel or battery storage what would your diesel control setting would you use? With batteries I would try both load following and cycle charging, and let HOMER tell me which is optimal. With the flywheel there is no difference between LF and CC, so I would just model LF.

What capacity are the Depth of Discharge inputs for the Lifetime curve? HOMER assumes that the battery needs replacement after a certain kWh throughput, which it calls the ‘lifetime throughput’. It assumes this lifetime throughput is a constant, independent of depth of discharge, rate of discharge, time spent at low state of charge, and every

In our model, we have set the converter parameters to have 0% Capacity relative to Inverter and an Efficiency of 1%. Essentially, we only want a converter to act as an inverter, and not a rectifier. (We aren't experts, but from what we can understand, the inverters on most PV systems cannot act as rectifiers). When the converter is set to only a

I am using the basic HOMER program for an off-grid home I am building. 48V battery bank will consist of 2V L16 lead acid. Will HOMER factor in energy required to provide periodic equalization charging? No, HOMER does not model that equalization charge.

Where can I find the flow battery model in HOMER? On the Battery Inputs window, if you click the New button you'll see the Create New Battery window, at the top right of which is a checkbox to indicate that the battery is a flow battery. If you define a flow battery and choose it from the drop-down list on the Battery Inputs window, that windo

HOMER computes the battery throughput (Qthrpt, kWh) as the sum of the discharge energy. HOMER estimates the lifetime of the battery in years by dividing Qlifetime (kWh) by Qthrpt (kWh/yr), where the battery throughput Qthrpt is defined as: the change in energy level of the battery bank, measured after charging losses and before discharging losses.

To import a battery from HOMER 2: 1) Create a .hmr file with the battery in it. You can add other components to the model if you like, but you don't have to. You can move more than one component at a time this way. 2) Open the .hmr file in HOMER Pro. In the "Open HOMER File" dialog, you'll need to change the file type from *.homer to *.h

Which are the initial values of Q1 and Q2 values of the KiBam model in the beginning of the simulation period? May the selection of those values affect the result somehow? HOMER assumes that the battery starts at 100% state of charge, so the initial value of Q is Qmax, and the initial value of Q1 is c * Qmax. The equation Q = Q1 + Q2 always wo

I notice that the minimum state of charge parameter affects parameters of the battery kinetic model, but I cannot see in HOMER help in what way. The apparent effect of the battery minimum state of charge on the kinetic battery model constants is interesting and surprising. When you change the minimum state of charge in the Create New Battery w

When HOMER calculates the battery life it uses the calculated lifetime throughput, giving a life of 5.1 years, not the suggested one which gives 11 years. Any suggestions? HOMER calculates the 'suggested value' of throughput, but the user (whoever creates the battery and adds it to HOMER's library) is free to make the lifetime throughput some

Somehow dimensions got lost, battery max. charge power is far to high (x 10) The maximum charge power is following the state of charge of the battery. With the new Hoppecke data I get a strange thing. Hoppecke gives 300A as a max. charge current, means with 48V 14,4 kW charge power. Now, although I have 2 Strings the max. charge power keeps to 1

The maximum charge rate variable imposes a limit on the rate at which the system can charge the battery bank. That limit is directly proportional to the amount of "unfilled capacity" in the battery, where the unfilled capacity is defined as the battery's maximum capacity minus its current absolute state of charge. For example, consider a battery

As we saw in some articles the minimum SOC has an important effect in optimization of renewable energy systems. If we want to consider different minimum SOC in our project, how we can carry out this? In battery input windows of HOMER it is an icon (NEW) that when we click it, a new window is opened with the specifications of a type of battery (for

This article describes how to make a battery model with the Advanced Storage Module (ASM) that fits a battery with an efficiency curve instead of the capacity curve used in HOMER. This article also provides some insight into how losses are modeled in the ASM. This article assumes that you have purchased the Advanced Storage Module, and you have re

Where can I put a charge controller? HOMER does not model the battery charge controller as a separate component. So you must include its cost and efficiency in the values you specify for other components. If you are simulating a PV-battery system or a grid-connected PV system, the best place to include the charge controller costs and efficie

The built-in controllers for HOMER require that all batteries are located on the DC bus. For some designs, particularly for larger microgrid and island grid systems, you may want to interconnect components via the AC bus. This can also be a useful approach when you are in very early design and want to get quicker answers, since getting rid of the n

Can I simulate PV-Wind-Diesel without designing a Battery Bank or by designing a very small one? Yes, you can simulate a PV-wind-diesel system without a battery bank. In many cases a battery bank could significantly reduce the cost of energy, particularly in combination with renewable power sources. But HOMER does not force you to consider a

Have you modeled a Synchronous condenser in HOMER before? HOMER does not model power factor or voltage, so it cannot recognize the value of the power factor correction and voltage support that the synchronous condenser provides to the system. That’s why HOMER does not explicitly model synchronous condensers, nor tell you when you need one. T

How is the power (kW) represented in this model? The finite capacity of the battery and the fixed length of time step impose an inherent limit to the charge and discharge power of the battery. For example, if you are modeling a 10 kWh battery with a 1-hour time step, the discharge power can’t exceed 10 kW, and neither can the charge power. If

I would like to know more about how HOMER uses the flywheel inputs The flywheel in HOMER is simply a source of operating reserve, so you need to really understand how HOMER models operating reserve. HOMER can simulate the system operations in time steps down to single minutes, so that may be a better way to model the Beacon flywheel. There ar

Do you have plans to add a flywheel storage option to HOMER? Yes we do have two types of flywheel models in HOMER Pro: 1) Reserve Model/Flywheel model 2) Idealized storage model The reserve model, as the name suggests, provides operating reserve capacity to the system. It also needs a constant Parasitic load to operate. The idealized storag

We're working on the design of a solar powered cathodic protection system where the requirement is NiCad batteries. Since they operate on different voltages and have quite different deep-cycle characteristics, can HOMER actually handle them? HOMER's battery module is flexible enough to model a fairly wide variety of energy storage technologies,

I am wondering if I can put storage such as Pumped Hydro, CAES, etc. in a model? HOMER cannot explicitly model pumped hydro or CAES. But if your system is all AC, you can model CAES and pumped hydro fairly well with the existing battery module. The battery has to go on the DC bus, but if your system is all AC you can specify a huge, free, and

If it functions as an electrical storage mechanism with a particular capacity and a particular round-trip efficiency, then the changes we made to HOMER’s battery module should allow you to model pumped hydro. When you create a battery you can choose whether to specify the capacity with a capacity-versus-current curve, which would be appropriate fo

How does HOMER take the decreasing of the batteries charge efficiency during its lifetime? HOMER does assume a constant round trip efficiency, so it does not account for the fact that in real life, performance worsens over the lifetime of the battery.

Products: HOMER Grid 1.1 and HOMER Pro 3.11 The HOMER® software can model a lot of different storage technologies, from pumped storage, to supercapacitors, to any number of traditional and advanced battery chemistries. To achieve this, it uses a range of storage models that you can use to best match almost any storage technology that you might wan

Is HOMER able to determine that a flywheel offer spinning reserve? Yes, HOMER recognizes that the flywheel provides operating reserve (our term for spinning reserve), so the presence of the flywheel reduces or eliminates the need for the diesel plant to provide operating reserve. That should allow the diesel plant to operate fewer or small gen

Click on a question below to learn more. The battery models are not easy to understand. How can I understand what parameters define HOMER's various battery models? How does the simple model account for variations of battery voltage as a function of SOC and charging/discharging current? How is the CYCLE defined?​ Is battery calendar

Does HOMER adjust the effective battery capacity with temperature? No, unfortunately HOMER does not account for the impact of temperature on the battery.

How do I account for the impact of cold temperatures on batteries for stand-alone solar systems? Effect of internal temperature on your battery can be modeled using the Advanced Storage Module (ASM) in HOMER Pro. Two types of temperature curves determine how it impacts your battery's performance. 1) Temperature (C) vs Capacity (% of nominal) 2

The Vanadium Redox Battery (VRB) is a type of flow battery that is composed of 2 primary parts: 1. The cell stack, where the conversion of electric energy to and from chemical energy takes place. The size of the cell stack determines how much power can be charged and discharged in the VRB flow battery. 2. The electrolyte, which stores the energy

The Zinc Bromide Battery (ZBB) is a type of flow battery that uses pumped zinc and bromide as the electrolytes that react in the cell stack to charge and discharge. In HOMER, ZBBs are specified with: - Nominal capacity in Ah that specifies how much energy may be stored in the battery -lifetime in years, which specifies the expected life of the co