Powerstation - costs and benefits

Reading time 5 minutes

Updated - January 5, 2025

A power station provides power on the go, portable, practical, good? Is the benefit in proportion to the cost?

In principle, yes, if you know what you're getting into. After all, the Powerstation also needs to be charged - and for that you need plenty of sunshine if there is no socket within reach. And things can quickly get tight if you're not traveling in the sunny south.

What you need to consider before purchasing a power station, as well as a cost-effective alternative, is outlined below.

Models and performance ranges

A wide variety of services are offered under the term power station. While the familiar power bank has so far been known for charging cell phones, tablets, ear buds, etc., manufacturers of power stations advertise the possible operation of induction stoves, microwaves, toasters, grills, refrigerators, computers, laptops, etc..

Outputs of up to around 12 kW are advertised. Some manufacturers even allow modular cascading of battery modules in order to provide these higher outputs. However, this option is usually only available within the manufacturer's own product range. This is ensured by individual, manufacturer-specific cable connections.

Less in than out?

Advertising claims such as "Reduce your energy costs" suggest that you use less electricity with such power stations than before.

Of course, this only applies if they are NOT charged from the mains, but exclusively via solar energy. And the often advertised "fast" charging, usually up to 80 %, only works in optimal sunlight during the few midday hours in the middle of summer. However, this is not enough for a full charge with a manageable number of solar modules.

Charging from the mains, on the other hand, is quicker because a constant charging current is available. Regardless of whether charging is carried out using mains or solar power, more electricity must always be supplied than can be drawn. At least as long as the perpetuum mobile has not yet become a reality.

Portability and its limits

In addition to the weight of the power station, including any additional battery modules, cables and solar panels, the initial portability is increasingly becoming a logistical challenge. And the acquisition costs for a full expansion quickly rise towards five-digit invoice amounts.

Starting up the induction hob or coffee machine in the tent is a nice idea, but who wants to lug around a trailer full of technical equipment?

It is more realistic to be able to supply the laptop, StarLink for the Internet connection in remote locations, including some lighting and the charger for the cell phone or tablet with power. But then again, spending a round thousand on this might make some people think twice.

The question always remains: what must(!) I be able to supply with it and for how long? Do I have enough sun to compensate for a day/night's consumption with solar energy, or is it possible to charge overnight with mains power?

The more you have to answer these questions in the negative, the less worthwhile it is to invest in such equipment. After all, a battery that is more empty than full and that cannot be reliably charged with sufficient energy in the foreseeable future is of little or no use.

Can't it be cheaper?

... some will ask themselves in view of prices in the thousands. Yes, it would, if it weren't for the small, recurring but that offers "slightly" poorer battery quality at a "slightly" lower price. In other words: you get what you pay for.

But what is a "little bit" worse battery quality? Well, whether the manufacturer guarantees 1,500, 3,000 or 6,000 cycles, for example, that alone would justify a double to quadruple price. It is therefore easy to imagine that a battery with the same nominal capacity can cost between 250 and 1,000 euros.
Another factor is whether the battery contains a built-in BMS (battery management system) and a balancer (for the purpose of cell equalization). Even if this only accounts for a few euros in production, such items also increase the price for the end customer.

Alternative?

One alternative is to build your own. If you accept a less attractive housing design, this is considerably easier on the wallet and even offers higher performance.

Logistically, the challenge of performance remains the same, because performance requires physical storage space, just as solar panels require space depending on performance.

The robustness of the equipment simply depends on the choice of housing. An industrial or MIL-standard enclosure may not win a design award, but it allows rough handling with good protection of the built-in components.

With IP65-compliant cable connections, even water poses no serious threat to the technology.

In the Article describes such a project, albeit on a larger scale. As the number of batteries, and therefore the output, is scalable, any variant can be planned and implemented.

In order to maintain modularity, and therefore also portability, no more than 4 EVE-Energy batteries (each weighing approx. 5.2 kg, with 6,000 (!) guaranteed charging cycles) should be accommodated in a "battery module" housing (with 13.6 V DC connection for the charging module). This allows 13.6 V packs to be converted into four individual batteries of 3.4 V each with 280 Ah, corresponding to 3,800 Wh - currently at around 450 euros (without housing) including BMS with up to 400 A!

The "charging module" should contain a Victron 230 V mains charger for LiFePo4 batteries with 13.6 V 30 A, a Victron MPPT controller 100 V 30 A for connecting the solar modules, a DC connection for the battery module and USB connections. Total currently, without housing, at around 550 euros.

The "230 V supply module" includes the Victron inverter with a nominal 2,000 W, the corresponding fuses, 230 V sockets (IP 65 - ! -), the DC connection for the battery module and USB connections and costs around 650 euros.

Those who can cope with less power can also choose a 1,000 W inverter, while those who need more can choose larger devices.
24 V or 48 V systems should be considered for outputs of around 3,000 W and above. On the one hand, such versions are more cost-effective, on the other hand they do not require such large cable cross-sections, which in turn results in cost savings and more flexible cables.

All in all, a power station with 230 V 2 kW, 13.6 V 280 Ah, or 3,800 Wh for around 1,650 euros plus three housings, fuses, plugs, sockets and cables. This should be an unbeatable undertaking in terms of both price and quality.

p.s. Please note that the performance data given are mostly maximum performance data. When dimensioning, you should assume a maximum load of 70%. In this way, you avoid continuous operation at the load limit, thus extending the service life of the technology and, if necessary, you still have some reserve that can be called upon for a short time.

p.p.s. Victron has the advantage of a worldwide service network, which means that spare parts and service are always available.

Housing

Plastic boxes with IP65 standard can be used as the preferred housing. The corners can be protected from damage and impact with metal corners in combination with screw-on rubber feet. Screw-on, ergonomically shaped handles allow safe and comfortable handling.

The good old ZARGES box, synonymous with stability and tightness, may also be suitable, but should then be very well covered on the inside with plastic panels, protected against electrical short circuits. All in all, a rather costly undertaking ...

Old Bundeswehr transport boxes can also be used as a substitute.

Solar module(s)

Solar modules with an open-circuit voltage of up to 100 V, a nominal charging current of up to 50 A and 700 W nominal PV power at 12 V can be connected to the MPPT controller planned above. This means that the range of modules that can be used is very broad.

There are flexible modules, often also called folding modules, and rigid modules, as they are commonly known. Unless flexible modules are absolutely essential (e.g. for logistical reasons), rigid but bifacial modules are recommended.

Bifacial modules generate electricity on both sides and thus achieve a good 20 % higher output than modules of identical surface area constructed on one side.

Insurrection

An elevation is helpful for almost optimal alignment with the sun. Similar to an easel, this can be two aluminum profiles connected to each other by means of an X-shaped stiffener, which are attached to the side of the upper narrow side of the module so that they can be rotated and locked.

When folded, the construction hardly takes up any additional space, but allows the angle of inclination to be adjusted and maintained even in windy conditions.

If you want to be on the safe side, you can provide the profile ends and the two corners on the underside of the module with a bracket that has a hole in the middle through which a sturdy tent peg can be hammered to prevent it from lifting off.