Overview of the autonomous power supply system at home KSTAR BluE H5-10

“There is no magic in energy”… That’s how an article on The Frontier that described methods of achieving energy independence began exactly one year ago. However, it is precisely magic that when the power goes out, the entire house or apartment continues to operate as if nothing had happened. Last year’s article stated that a reasonable peak of energy independence for a private house in Ukrainian conditions is an inverter, a battery, a generator, and (optionally) solar panels. Unfortunately, the solar part never came to fruition in practice, but now we have the opportunity to compare our own system based on simple components with a top-level all-in-one solution. So to speak, to see how Cadillac differs from Chevrolet.

So, we tested the KSTAR BluE H5-10 system, consisting of a BluE-S 5000D inverter and a BluE-PACK10.2 battery, worth more than UAH 280 thousand.

Specifications

It makes no sense to give all the technical characteristics of the inverter and battery pack, because they take up 5 pages in the user manual. This is especially important when selecting solar panels for an existing system or for countries with different grid parameters, but not so important for a general overview. So let’s leave what should be of interest to the average user:

Overview, installation and testing

The entire system takes up three huge cardboard boxes. They contain absolutely everything that is needed to connect the system to the prepared electrical network of the house:

• KSTAR BluE-S 5000D inverter;
• Connectors for connection to 220 V network;
• Two BluE-PACK5.1 batteries;
• Wires for connecting the battery to the inverter and to each other;
• Inverter and battery wall mounting kit.

What is called BluE-PACK10.2 in the specification is actually two separate BluE-PACK5.1 batteries with a set of connectors. In general, we need to clarify the KSTAR product range, because there is some confusion. There are three inverter variants (BluE-S 3680D, BluE-S 5000D, and BluE-S 6000D) and one BluE-PACK5.1 battery that can be purchased separately or as part of complete systems in the following combinations:

In other words, all battery options are actually sets of the corresponding number of BluE-PACK5.1 and wires for connecting several batteries together. If desired, the owner of, for example, a KSTAR BluE H5-10 with a capacity of 10.2 kWh (with two BluE-PACK5.1s hiding under the BluE-PACK10.2 label) can buy one or two more batteries and get a system with a capacity of 15.3 or 20.4 kWh. In addition, KSTAR BluE-PACK5.1 batteries and inverters (including the 6000W BluE-S 6000D) can be purchased separately – for example, to improve an existing system with simpler components.

The whole system is very heavy, and the batteries can be moved and installed only by two people. All you need for installation is a wall and a flat floor – everything else is included. First, the first battery is attached, then the second battery is attached to it, and then the inverter with the cable box that is part of its design is attached to it on top. Assembly takes literally 10 minutes, because there is no need to invent anything or buy additional parts. If you want to add 1 or 2 more battery packs to the system to increase the total capacity to 15 or 20 kWh, you need to install them on the side and also buy an installation kit to connect them to the main system. 4 BluE-PACK5.1 units are the maximum configuration, and it is not possible to add a fifth, but it is hardly necessary.

Cables connecting the battery to the inverter and the second battery in parallel with the first

There are certain requirements for installation:

• Not in the living room;
• Out of direct sunlight;
• Do not allow temperatures below freezing;
• No higher than 90% humidity;
• Good ventilation;
• Leave at least 600 mm from other objects on each side.

Since the system complies with the IP65 protection standard (full protection against dust, protection against water jets from all directions), the manufacturer claims that it can be installed outdoors. Unfortunately, this is not possible in Ukraine due to the subzero temperatures in winter: while the operating temperature range of the inverter covers any of our weather without any problems, according to the instructions, it is forbidden to charge the batteries in subzero temperatures and discharge them below -10 degrees. Therefore, in our conditions, we will have to install it in some kind of technical room.

Specifications of the inverter

To be honest, the result of the assembly is impressive: unlike typical systems with conventional batteries, the product looks exactly like a Tesla Powerwall product, not a “homebrew”. And this applies not only to appearance. All connections are made on high-quality expensive industrial connectors, all the wires in the kit are fully prepared for quick connection… The inverter is about four times heavier than the usual budget solutions of the same 48 V, 5 kW class.

Battery specifications

It is important to explain about the batteries separately. Each KSTAR BluE-PACK5.1 unit is assembled on the basis of individual LiFePO4 batteries manufactured by CATL. We have not disassembled the battery, but usually these are 3.2V cells, i.e. there should be 16 of them inside for a 51.2-volt assembly, provided that 100 Ah cells are used. These cells have different quality from one manufacturer to another (and here CATL is in good standing in the industry). And they can also have different guaranteed number of charge-discharge cycles – for example, in Ukraine, you can find CATL for “more than 2000 cycles,” while the KSTAR product has the highest quality batteries – up to 10,000 cycles, according to the manufacturer’s statements and a 10-year (!) factory warranty on battery performance.

Unfortunately, it’s impossible to verify this even in long-term testing, so we’ll have to take our word for it – at least the Ukrainian seller’s warranty is 36 months, which is also quite a long time. There are certainly cheaper batteries on our market than KSTAR, but if they fail in three years and KSTAR lasts ten, the total cost of ownership of the “cheap” system will be twice as high. The same can be said for the inverter, because typical Chinese products from local sellers have a warranty of 30 days (!) to 12 months, unlike the 3-year warranty for KSTAR in Ukraine (the manufacturer even gives 5 years).

The batteries physically have only a simple 4-segment charge-discharge indicator. Nevertheless, they transmit a large amount of “telemetry” about the status to the inverter, where it can be viewed on the control panel display. To be honest, it all looks like 1990s technology: A 4-line backlit LCD display, 4 control buttons, all kinds of abbreviations in the message texts… Of course, the manual fully documents the functions, but fortunately, only the installer needs to use this panel during the system setup process at the first start – then the user can do all the monitoring remotely using the Wi-Fi adapter included with the BluE-H5 and the mobile application.

The user manual is 85 pages long, and you should take its contents seriously if you want to understand the system or install it yourself. This applies not only to the physical connection, but also to the settings, because they have no “foolproof” protection and when you learn by “poking” you can do a lot of damage that will not be covered by the warranty. If the installation is done by a wizard, the user may not open the manual at all, because everything else happens automatically.

Switch panel under the inverter

An attentive reader will have already noticed that the package description says that there is everything to connect the system to a prepared power grid. This is true, but the key word there is “prepared”. Even if the house already has a backup power supply from a generator, this does not mean that everything is ready for easy installation. And even more so if an independent power source is added for the first time. Replacing the existing system with the KSTAR took the technician about half an hour, but from scratch it can take a whole day, depending on the complexity of the electrical circuit.

Minimal preparation of the power grid: at the bottom for a three-phase generator, at the top for a single-phase battery system

We can give some advice on how to prepare for ordering a home energy supply system. First, you need to calculate your own needs to understand which system will minimally satisfy them. This has been described in detail in the article “There is no magic in energy”, so we will not repeat the importance and methods of calculation. Let’s just note that it is very good to optimize consumers. Ideally, a separate “fault tolerance line” should be set up with critical electrical appliances to be powered by the backup system, because otherwise you can unnoticeably use up battery power on something that may not be very necessary in times of power outages, such as a boiler.

For contrast, here is the switchboard of a typical budget inverter with screw wires and computer-grade connectors

Since the KSTAR BluE H5-10 is a single-phase system for a 220 V network, and the author has a three-phase 380 V network on the site, the solution was quite simple: one of the phases was recognized as “unbreakable”, and all critical consumers had to be transferred to it and non-critical ones, such as heating convectors, had to be removed. It took some time and required additional costs, but as a result, when the 220 V network goes down, the switch to inverter power is not noticeable at all, and at the same time, there is no need to run around turning off large appliances to save battery life.

KSTAR inverter switchboard with industrial connectors. Assembled in a hurry for test purposes, of course, all connectors are sealed according to the IP65 standard

The testing process revealed another pleasant aspect of KSTAR: the whole system makes minimal noise even under high load, while it is not very pleasant to be in the same room with a working budget inverter for a long time. True, there is a high-frequency sound from the inverter, but it is not audible from 2-3 meters away.

Wi-Fi module in place

The system monitoring application is called Solarman Smart, which is not exclusive to KSTAR but also works with other similar systems. The manufacturer offers to download the APK from a Chinese server, but the app itself is available in the regular Play Market and App Store. It has some compatibility difficulties: it requires only a 2.4 GHz Wi-Fi network, and special characters in network names and passwords are not supported. But then setting up the Wi-Fi adapter connection is simple and takes exactly one time. As already mentioned, the operating parameters can be changed only through the inverter display, and only monitoring works in the app – but this is enough and it is even better that potentially destructive changes cannot be made through the app.

Solarman Smart mobile application. The second and third screenshots differ in the state of mains power supply

The interface is, let’s say, “working”, with no claims to convenience and friendliness, as in Ecoflow or Bluetti. Nevertheless, it does its job and provides opportunities for very extensive monitoring of system parameters, including the collection of statistics by day, month, year, and since the start of operation. And here’s the great news – in addition to the mobile application, there is a web version that makes analysis much more convenient from a desktop PC.

Of course, the name of the app itself already suggests that it is tailored for solar power plants. Without panels, a lot of features are not available, but KSTAR has provided both the inverter and battery packs with full telemetry so that behavior can be studied in a thoughtful way. And it fully meets the declared characteristics.

In typical mode, without conscious consumption restrictions, the author’s house consumes an average of 0.3-0.5 kWh. Accordingly, one full charge of the KSTAR batteries lasts for 20-30 hours. This is several times more than the “4 hours in 4 hours out” blackout patterns that Ukrainians are notorious for due to the war. And it even covers most cases of local emergency outages when the power grid is damaged due to bad weather – usually, power company crews manage to repair everything in less than a day.

If you are very conscious about your consumption and reduce it to Starlink, a couple of LED lights, and charging a laptop, you can reduce the load to 100 Watt-hours, but you shouldn’t forget that the refrigerator consumes 1 kW per day and the well pump will add something else depending on the activity of use. However, in this case, the daily consumption is about 3500 watts and the system can last almost three days without recharging!

On the contrary, if you connect an electric convector for testing purposes to bring the constant consumption to 2 kWh, the KSTAR BluE H5-10’s capacity lasts for 4.5 hours. Not exactly 5 hours because the settings set the minimum battery charge at 10% to ensure long battery life. At the maximum power of 5 kW, the system is expected to last almost 2 hours. There is no rational reason to use it like this in an ordinary household, but the possibility exists.

Charging from the mains takes about 4 hours because it was limited to 16 A. The system allows you to speed up this process by half, but then you also need to have a 5.5 kW generator if you want to recharge both with it and from the mains when it appears without reconfiguration.

Conclusion

It would be unfair to attribute general qualities of such systems in general to the system under review, but the ability to “not feel the lights go out” feels almost like magic, as mentioned at the beginning of the article. It’s magic compared to a generator that needs to be refueled and started. And it’s magic compared to portable systems like Ecoflow, where autonomy is limited to a few outlets.

The stories of last winter, when such systems were openly offered to replace the generator and even the terrible term “electric generator” appeared as opposed to “gasoline generator”, are also incorrect marketing. After all, a system with a battery can only supply the accumulated electricity, not actually generate it from some other energy source.

However, from a practical point of view, both in ordinary life (when sometimes the power is cut off in the countryside due to accidents) and in anticipation of possible regular power outages in wartime, such a system can greatly reduce the load on the generator. It is still necessary to have a generator in case the battery is already discharged and the grid has not appeared.

And here is the following calculation, which was given in last year’s material and now it makes sense to quote it in full, because according to the results of testing KSTAR BluE H5-10, all these theoretical calculations were true one to one:

“We have a system with 48 V 200 A (9,600 Watt-hours) LiFePO4 batteries and an inverter that charges them with a current of 50 A (2,400 W). With a consumption of 300 Wh, the charge will last for 32 hours. If you turn on the generator at this point, it will need to work for 4 hours, delivering 2700 Wh (300 W of consumption + 2400 W of charging), after which the system will be ready to work for the next 32 hours from the batteries. Each such charging cycle will take about 6-8 liters of gasoline. As a result, a month of full round-the-clock autonomy will cost 120-160 liters of gasoline (UAH 6000-8000 in December 2022 prices) and 80 hours of generator life (one oil change after 50 hours).

If you try to calculate a similar autonomy for a house without a battery system at all, you will get a titanic 30*24=720 hours, during which, in the most economical case, 500 liters of fuel (25000 UAH) will be burned. The oil will need to be changed 14 times, so the cost of 10 liters will add about 3000 UAH… For a more realistic calculation, of course, in the second case, we need to include an adjustment for shutdown every 4 hours for rest, which will reduce all the figures by about 25%, but during this time the household will be without power at all… And it is absolutely unknown how many “motor days” the average generator will live in this mode without overhaul. In the first case, we have normal operation of all system components, in the second case, we have an attempt to set a marathon record for generator survival.”

If everything else has not yet become an argument for purchasing the system, then the generator on the farm will definitely vote for unloading it and extending its life before repair. And here the system capacity of 10 kWh is very inspiring. We can say that 5 kWh is the minimum for the normal operation of the system for the whole house, but further expansion to 15-20 kWh, although it will decorate, will not bring radically new benefits.

Another reminder of the difference in quality is the battery connectors: the KSTAR industrial solution and the typical “automotive”…

What’s next, if not additional batteries? Definitely – 5 kW solar panels! After Solarman Smart measurements have shown a ridiculous level of “unbreakable” consumption, one can believe in the reasonableness of such a step even in winter and even in Kyiv latitudes. At the very least, for the sake of long-term “apocalyptic” energy independence without gasoline and worrying about the generator’s motor life. In normal life, this should provide tangible savings on electricity, and in the summer, perhaps even additional income. And if in 2023 the author did not get to solar energy, now he has more motivation.

It’s hard to take an adequate photo in the garage, because KSTAR had to be placed in a very temporary place for the test, but the difference in the feel of the product compared to a set of a budget inverter and gel batteries should be noticeable even from this angle

If we talk about the impression of KSTAR BluE H5-10, everything is very simple: “you get what you pay for”. Yes, from the point of view of bare characteristics, this system does not differ from self-assembly at about half the price. But it’s only the long warranty and the promised 10,000 life cycles of the LiFePO4 battery that makes it worth paying extra, because it will make the total cost of ownership of the product actually lower than replacing cheap components that have failed. And all the industrial beauty and product feeling in this case is just a bonus. Returning to the automobile analogy at the beginning of the article, Cadillac did turn out to be more expensive than Chevrolet, but equally more interesting from all angles.