Offgrid systems – Self-sufficient power supply for cabins, construction sites, and more

Yes, but the planning must take winter conditions into account. In snowy Alpine locations, for example, PV modules sometimes only get a few hours of sun in winter and can be covered by snow. This can be remedied by installing the modules at a steeper angle (so that snow slides off/facade) and additional generators: some systems integrate wind power or an existing small hydroelectric power plant to supply electricity in winter. It is important to have a large storage capacity so that even longer periods of bad weather can be bridged. In winter, a generator often takes over the supply temporarily, especially if huts are not permanently occupied – in this case, a small frost-protected generator is set to start automatically when the battery voltage reaches a critical level. Another current trend is heating mats or housings for batteries to keep them at the right temperature (lithium batteries must not be charged at sub-zero temperatures). Overall, an off-grid system is feasible in cold winter climates, but requires sufficient dimensioning and, if necessary, hybrid support. Example: In Canada and Scandinavia, hybrid solar-wind-diesel systems are used to get Arctic Circle stations through the dark winter. With good planning, there is no power outage even in December.

This is done via the inverter/charger, which has a generator input. Modern off-grid inverters (e.g., Victron MultiPlus/Quattro) can feed in generator or mains power and act as a charger at the same time. When the generator is running, it supplies the consumers directly and charges excess power into the battery. When the generator is off, the inverter resumes supplying power from the battery. An automatic start/stop control is important: a battery monitor detects when the charge level is low and sends the start command to the generator via radio or cable (in the case of appropriate units, via two-wire start or intelligent generator control). The generator can also be kept ready to start during load peaks. Many systems allow threshold values to be defined (e.g., generator on at <30% battery level, off at >80% charge). This means that the combustion engine only runs when necessary. Incidentally, existing diesel generators can also be retrofitted with hybrid technology by installing a suitable inverter and storage unit – the generator is then effectively downgraded to a backup, which saves fuel and engine hours.

As a rule, no – since a true stand-alone system is not connected to the public grid, there is no need to notify the grid operator, as is usually required for grid-connected PV systems. An off-grid solar system can usually be installed without registration. However, there are a few points to consider: If the system does have a switchable grid backup function (i.e., it is occasionally connected to the home grid, e.g., via a grid switch), it must be ensured that no feed-in to the public grid is possible (stand-alone inverters do this by not feeding into the grid during grid operation). As long as no energy is sold and no feed-in to the grid takes place, notification and approval procedures can usually be implemented without any problems. If a system is grid-switchable, this must be clarified with the grid operator. Nevertheless, it is advisable to check local regulations – in some countries, certain size limits or fire safety requirements apply. Building permits may be required for very large island systems (e.g., commercial), but for typical applications (cottages, garden sheds, boats, motorhomes, construction power, etc.), the bureaucratic hurdles are low. It is always advisable to consult a professional installer who will set up the system in accordance with standards to ensure safety.

Pleasantly low. Solar modules are largely maintenance-free—occasional cleaning (in case of heavy soiling or snow cover) is all that is required. Batteries (especially lithium) do not require regular maintenance such as refilling with water (previously necessary for lead-acid batteries). The only important thing is to avoid extreme deep discharge or overcharging – but this is automatically regulated by the battery management system and the inverter. An annual check of the system is recommended: this involves checking connections, updating the control software, and monitoring the battery capacity. If a generator is available, it requires classic servicing (oil change, filter change depending on operating hours, check before the winter season, etc.). Overall, a well-designed off-grid system runs very autonomously. Many users report that they hardly ever have to intervene throughout the year – the system manages itself. Remote monitoring provides proactive alerts (e.g., notifications when the battery is low or a module has failed). This allows you to react early, before power shortages occur. Maintenance costs are very low compared to continuous operation of a diesel generator – there is no need for daily refueling or frequent engine maintenance. In the long term, you should plan to replace the battery storage after approx. 10–15 years (for lithium, for lead possibly after 5–8 years), depending on usage. Experience has shown that inverters/electronics also last for many years, as they are designed for continuous operation. The bottom line is that off-grid systems are reliable and easy to maintain if they have been professionally planned.

The costs can vary greatly depending on size and components. Small DC solar sets for garden sheds are available for just a few hundred euros. For a self-sufficient mountain hut or a residential building with several kW of PV and a large battery, the cost can run into tens of thousands of euros. Basically, the costs are made up of: PV modules (~15–25% of the total cost), battery storage (often the largest item, ~30–50%), inverter/charge controller (~20%), and installation/cabling/substructure (~10–20%). A rough guide for a good quality system (e.g., ~10 kWp PV, ~20 kWh LiFePO4 battery, hybrid inverter) is around €15,000–25,000 fully installed, depending on the brand and location. In addition, you need to consider whether a generator is planned. Here, you can use an existing one or factor in a new one for a few thousand euros. It is important to compare with alternatives: although the initial costs are higher than a simple DIY store generator, fuel costs are largely eliminated for years. Especially in remote locations (where every liter of diesel would have to be delivered by helicopter), solar systems often pay for themselves in just a few years. Compared to grid connection costs (which can be extremely high in remote areas if kilometers of cable have to be laid), a stand-alone system is often the cheaper option. In addition, there are government subsidies for renewable energies that can cover part of the investment. In the long term, the sun does not send a bill – after the initial investment, the running costs are minimal.

That depends on the requirements. High-quality off-grid components such as those from Victron Energy are considered the gold standard among experts—they offer very high reliability, flexible expandability, and professional monitoring functions. Victron devices allow, for example, fine configuration, parallel connection of multiple inverters, remote firmware updates, and often come with a 5+ year warranty that can be extended by 5 years upon request. However, they are more expensive to purchase and require some space for the individual components. All-in-one devices (often from China, e.g., MPP Solar, Growatt, etc.) are significantly cheaper and often easier to install, but usually offer less performance, reliability, monitoring, and support. For a simple weekend home with a limited budget, such a combination device may well suffice—many users are satisfied with it as long as the performance class is suitable. However, there are differences in service life and efficiency: cheaper devices sometimes have high internal consumption (they run 24/7 and consume 50–100 W themselves, for example, which is unnecessarily high for small solar systems) and do not cope well with overload or continuous load. If you have a critical application or want long-term peace of mind, you are better off with quality products – these often run reliably for decades. In addition, established brands offer good technical customer service and a community that can help with questions. Conclusion: “You get what you pay for.” For a serious, permanently operated off-grid system, it is worth investing in robust, efficient hardware. However, for simple requirements or test projects, it is perfectly possible to start with cheaper solutions – an upgrade is always possible later. Many start small and then upgrade step by step, for example, when the cheap inverter fails. In any case, safety should not be sacrificed: Certified devices with protective functions (short circuit, overtemperature, etc.) are a must, regardless of whether they are expensive or cheap.

Thanks to modern electronics, monitoring an off-grid system is very convenient. Many inverters and solar controllers offer Bluetooth or Internet connectivity. For example, the Victron VRM Portal allows you to check the status from anywhere: current PV power, battery charge status, current consumer load, generator status, etc. Alarm functions are also common—such as an email/text message when the battery level becomes critical or when a device fails. There is often a display on site (e.g., a Color Control GX or similar) that shows all values in real time. For many users, it is motivating to see how much solar power has been harvested and how high their own consumption is. Remote monitoring is also valuable for support purposes: with your permission, a technician can connect to the system and check or adjust parameters. This allows 90% of all problems to be solved without anyone having to travel to the system. This is a major advantage for very remote installations (e.g., mountain huts that are inaccessible in winter). By the way: most monitoring devices require internet access – this is usually provided via the mobile network (if available, e.g. via a 4G router or SIM card in the monitoring device). In extremely remote areas, satellite internet (Starlink, VSAT) is also used to transmit data. The costs for this are justified in special cases if it means you can avoid expensive on-site service calls. In short: Your island system doesn't have to be a shot in the dark – with today's tools, you can keep an eye on your own small power plant park at all times.