FAQ - Frequently asked questions

There is no one-size-fits-all solution for off-grid systems. We have collected the most frequently asked questions for you in our FAQ.

Operating mode

Yes. Basically, our devices are developed for continuous operation. Therefore, they also achieve the longest stack life under these conditions. Frequent and rapid startup and shutdown, on the other hand, can have a detrimental effect on performance. This is because the stacks reach temperatures of around 800 °C in the core system. Please contact us if you want to integrate Sunfire-Remote into a frequent start-stop operation.

Yes, you can back up your application with Sunfire-Remote, e.g. in case of a longer power failure. The maximum duration of the bridging time is determined by the amount of stored fuel. The main advantage over diesel gensets is the significantly lower maintenance and servicing costs for the generator and fuel tank.

It should be noted that the Sunfire remote is based on high-temperature solid oxide fuel cells (SOFC). They reach temperatures of around 800 °C in the core system. A start-up process takes between 4 and 8 hours, depending on the device type and ambient temperatures. During this time, a battery must provide the energy for the customer load and the start of the Sunfire Remote. Our experienced team will be happy to assist you with design questions.

This is easy to implement. Sunfire-Remote has an IP gateway that can be integrated into the customer's network. A combination with mobile routers is also possible.

Sunfire-Remote is currently approved and certified for use with propane and natural gas. This means that it can be used with piped natural gas, CNG, or with LPG with a propane content of >95% as a logistical fuel in cylinders and tanks. In the unit, a reformer converts the fuel into a hydrogen-rich gas (reformate), which is then electrochemically converted in the fuel cell stack.

For sustainable and emission-free operation, we recommend biogenic propane from renewable resources or synthetic e-propane from renewable electricity.

Our fuel cell units have an electrical efficiency of about 30 %. As a rule of thumb, 3.33 kWhchem fuel is needed to generate 1 kWhel. Also, there is 12.9 kWh of chemical energy stored in 1 kg of propane. Thus, about 3.87 kWhel can be generated from 1 kg of propane.

The devices are currently not suitable for operation with pure hydrogen. This is mainly because hydrogen cannot be readily used as a logistical fuel.

To store the same amount of chemical energy as propane, hydrogen requires more than five times the volume and the cylinders are nearly eight times the weight relative to the energy produced. In many off-grid applications, there is not enough space to store such quantities of fuel.
In addition, transport, storage and refueling with hydrogen are currently subject to strict safety regulations.

Nevertheless, operation with hydrogen will be possible in the medium term. Sunfire is developing concepts to be able to operate its fuel cell devices in hydrogen networks in the future.

We keep operating costs low. Because our fuel cells run unattended for up to 10,000 hours, maintenance and service costs are unbeatably low. The high efficiency also leads to a reduction in operating costs. Another positive aspect is that the fuels used are available at low cost almost everywhere in the world.

We will be happy to support you with the profitability calculation for your application!

Installation & Service

Our customers appreciate the simple installation. To put the units into operation, only the exhaust pipe, the gas supply and the battery need to be connected. For Sunfire Remote 900, a cooling circuit is additionally required. After all connections have been made, the unit can be switched on directly and monitored via the integrated IP interface.

Liability for defects shall commence at the time of assembly and commissioning, but no later than 3 months after delivery.

Sunfire is liable for defects that are due to material or manufacturing defects within the scope of the legal liability for material defects according to the General Terms and Conditions of Sale and Delivery.

The liability applies for a maximum of 2 years or 15,000 operating hours with a maximum of 30 cold starts (heat-up cycles) during the service life of the core module - whichever occurs first - within the scope of the statutory liability for material defects.

Individual adjustments

If your energy requirements are significantly higher than the generated energy of one device, two devices can be operated in parallel. In this case, we match the settings precisely to the respective requirements.

The coupling is uncomplicated. In most cases, neither a disconnector nor an interface between the devices is required. They run completely independently of each other by monitoring the state of charge (SOC) of the batteries.

In remote areas with limited seasonal access, it may be useful to have an additional fuse. To further increase reliability, two devices can be connected in parallel. In this case, the primary device is configured for continuous operation. The secondary device will only turn on if the other device is no longer able to charge the battery. This unlikely event may occur due to a fault or degradation at the end of the core system's life.

Many of our customers use Sunfire remote in photovoltaic hybrid systems. Our devices are well suited for this type of application. However, such installations require careful planning. All system components must be well coordinated to ensure reliable operation over the long term. As a rule, the photovoltaic system generates the required electricity in summer, while the fuel cell takes over in winter when solar radiation is low. This interaction reduces fuel consumption and logistical effort. Since the operating hours of Sunfire-Remote also decrease, the maintenance intervals and the service life of the fuel cell core system are extended.

Hybrid installation with small wind turbines is not recommended due to the high volatility of wind generation.