Charging with construction power or a generator – how are mobile storage units recharged?
A mobile battery storage unit is only truly useful on a construction site if recharging fits the workflow. A large grid connection isn't always necessary. Often, a small construction power connection is sufficient if the storage unit can charge continuously and then provide energy for peak loads, night operation, or mobile consumers.
In addition to grid charging, generator charging, hybrid solutions, and PV support are also options. Which variant makes sense depends on the duration of use, charging power, consumption profile, location, and construction site logistics. When planned correctly, the storage unit becomes a flexible buffer between the energy source and consumers.
Key Takeaways
- Grid charging is often the simplest solution: Even a small construction power connection can be enough if the storage unit is charged continuously over many hours.
- Generator charging is useful for changing locations: The generator specifically recharges the storage unit, while the storage unit handles partial load phases and peak loads.
- Hybrid solutions combine storage and power generators: Either as an integrated hybrid generator or as flexibly combined individual units.
- PV support can reduce charging times and fuel consumption: for example, via container roofs, mobile PV modules, or foldable solar arrays.
- Practical Tip: Never derive charging times solely from battery capacity. The crucial factors are charging power, remaining charge, temperature, consumer operation during charging, and real system limitations.
1) Why Recharging is Crucial
A mobile battery storage unit stores energy and then releases it when needed. On a construction site, this is particularly valuable because power demand and available connection capacity rarely match perfectly. In the mornings, several consumers start up, during the day, machines and chargers switch on and off, and at night, often only lights, cameras, routers, or container technology remain active.
For the storage unit to operate reliably, it must be clear where the energy comes from. The storage unit can be charged via construction power, generator, PV, or a combination thereof. The crucial factor is not only the maximum charging power but also when and for how long charging can take place.
A small connection can be very valuable if it is available long enough. A mobile storage unit converts continuous small charging power into high power that can be used for short periods.
2) Grid Charging via Small Construction Power Connection
The simplest charging source is an existing construction power connection. This doesn't always have to be a large connection. Even 32A or 63A can be sufficient in many applications if the storage unit charges continuously and doesn't need to be full in just a few minutes.
A 32A three-phase connection theoretically provides approximately 22 kW, and a 63A three-phase connection approximately 43 kW. In practice, however, the usable charging power depends on cable length, fusing, grid quality, the storage unit's charger, and other consumers on the construction site.
✓ Advantages of Grid Charging continuous
- Quiet and locally emission-free.
- Low operating effort.
- Very well suited for longer charging windows.
- Ideal if the storage unit can recharge during the day or overnight.
! Limitations of Grid Charging check connection
- A small connection means longer charging time.
- Other consumers may share the available power.
- Cable run and fusing must be appropriate.
- Load management may be necessary.
3) Generator Charging and Hybrid Systems
If there is no sufficient grid connection, a generator can recharge the mobile storage unit. This is particularly interesting for changing construction sites, temporary operations, or where little grid power is initially available.
In a hybrid solution, the generator does not run continuously for every small load. Instead, it specifically recharges the storage unit. The storage unit then supplies small and medium consumers, buffers peak loads, and enables quiet operating times. This allows the generator to be operated more frequently in a better load range.
Integrated Hybrid Generator
compact- Generator and storage unit are combined in one system.
- The control system is designed for joint charging and discharging.
- Good for standardized applications with clear operating logic.
Separate Storage Unit + Generator
flexible- Storage unit and generator can be used together or separately.
- Generator size can be selected per project.
- Existing generators can often continue to be used.
Generator as Charger
targeted- Generator runs only during defined charging windows.
- Storage unit then handles partial load and night operation.
- Fuel consumption and running time can decrease.
Depending on the project, SEV connects mobile battery storage units and mobile generators to create suitable hybrid solutions. The advantage: the devices remain flexible. A storage unit can work with a generator on one construction site and be charged directly from the grid or with PV support on the next construction site.
4) PV Support on Containers, Module Frames, and Open Areas
PV support is not a complete replacement solution for every construction site, but it can be a very sensible addition. Especially with longer standing times, construction containers, small base loads, or daytime operation, solar energy can recharge the storage unit and relieve the generator.
Possible options include PV systems on container roofs, such as with PowerTop solutions, mobile module frames, or foldable PV modules. Temporary PV areas next to the container or in open spaces can also be interesting if space is available.
✓ PV can help with … Solar support
- Container technology and base loads.
- Longer standing times on a construction site.
- Charging throughout the day with lower consumption.
- Reduction of generator running times.
! Properly assess PV weather-dependent
- Yield depends on weather, season, and orientation.
- Consider shading from buildings, cranes, or scaffolding.
- PV usually does not replace the main charging source for high loads.
- As a supplement, PV is often very useful.
5) How Long Does Charging Take?
Charging time can be roughly calculated: energy required in kWh divided by usable charging power in kW. An additional allowance is added for charging losses, temperature, power limitations, and the case where consumers are simultaneously supplied during charging.
Example: A storage unit needs to be recharged by 100 kWh. With approximately 22 kW charging power via a 32A three-phase connection, this theoretically takes about 4.5 hours, in practice somewhat longer. With approximately 43 kW via 63A, the theoretical charging time is about 2.3 hours, also plus reserves.
32A Three-Phase
approx. 22 kW- Good for continuous charging.
- Interesting for long standing times.
- For large storage units, plan longer charging windows.
63A Three-Phase
approx. 43 kW- Significantly faster recharging.
- Good practical size for many construction sites.
- Consider load management for other consumers.
Generator or PV
variable- Generator charging depends on generator power and charger.
- PV depends on sun, area, and system technology.
- Both can be combined.
6) Take the Storage Unit to the Construction Yard Overnight?
For smaller mobile storage units, it can be useful to take them to the construction yard in the evening and charge them overnight. This is particularly practical if there is no secure power connection on the construction site, if theft protection plays a role, or if the construction site should remain as quiet as possible at night.
For larger construction site storage units, taking them away overnight is not always practical. In this case, a fixed charging window on the construction site is more sensible, for example, via grid connection, generator, or PV support. The decisive factors are transportability, weight, charging infrastructure at the construction yard, and energy demand for the next working day.
For small and medium-sized storage units, charging overnight at the construction yard can be very practical. For large storage containers, a well-thought-out charging and security concept directly on the construction site is usually better.
7) What to Consider During Planning
The best charging strategy does not arise from a single metric. The interplay of energy demand, charging window, existing infrastructure, and consumer profile is important. A storage unit that buffers peak loads during the day requires a different charging strategy than a storage unit that supplies lighting and security technology at night.
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Record energy demand: Which consumers run for how long, what peak loads occur, and how many kWh are needed per day?
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Check charging sources: Construction power connection, generator, PV support, construction yard charging, or a combination thereof.
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Plan charging times: Do not only consider maximum charging power, but also real charging windows, losses, and parallel consumption.
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Assess flexibility: Individual storage units and generators can often be combined on a project-by-project basis and also used separately if required.
8) Frequently Asked Questions (FAQ)
Can a mobile storage unit be charged from a small construction power connection?
Yes, this is often exactly what makes sense. A small connection charges the storage unit continuously, while the storage unit later provides higher power or peak loads.
Can a generator charge a battery storage unit?
Yes. The generator can specifically recharge the storage unit. In hybrid solutions, the generator often runs for shorter periods and in a better load range, while the storage unit handles partial load phases.
Is PV useful on a construction site?
Yes, especially as support. PV on container roofs, mobile PV modules, or foldable systems can shorten charging times and reduce generator running times. However, the yield depends heavily on weather, area, and shading.
How do you calculate the charging time of a mobile storage unit?
Roughly: energy required in kWh divided by usable charging power in kW. In practice, charging losses, temperature, system limits, and simultaneous consumers are added.
Should the storage unit be taken to the construction yard overnight?
For smaller mobile storage units, this can be very practical. For large storage units, a charging and security concept directly on the construction site is usually more sensible.
9) Conclusion
A mobile battery storage unit can be recharged via construction power, generator, PV, or a combination thereof.
Small construction power connections, in particular, become much more usable with storage units because they can charge continuously and the storage unit later provides high power. Generators remain important when fast and independent recharging is needed. PV can additionally support the solution and reduce running times.
SEV connects mobile storage units, power generators, hybrid generators, and PV components to create flexible overall solutions for construction sites. This ensures that the energy supply is project-specific, economical, and adaptable.