Energy storage efficiency and prices determine economics – Commercial

From pv journal 06/2022

Based mostly on accessible data on system efficiency and pricing analysis carried out by pv journal Germany, the next evaluation seems on the effectivity of various photo voltaic plus storage programs accessible on the residential/business market in Germany. The System Efficiency Index (SPI) was developed by researchers at HTW Berlin and permits for comparability of programs throughout two efficiency courses. This 12 months, 21 programs participated, all of which may be discovered available in the market overview. One producer, Kostal, restricted itself to having its personal programs listed by way of the wholesaler EWS.

Within the smaller energy class, as much as 5 kilowatts, the hybrid inverter Fronius “Primo GEN24 6.0 Plus” got here out on high, along with the BYD “Battery-Field Premium HVS 7.7”. Within the bigger energy class as much as ten kilowatts, the “Energy Storage DC 10.0” from RCT Energy – additionally final years’ winner – achieved the best SPI worth with 95.1%.

Typically, the HTW Berlin researchers recorded a constructive improvement within the larger energy class, and a lot of programs which can be shut collectively by way of efficiency. Six programs achieved an SPI of greater than 93%, however in 2020, just one battery storage system managed this. For the smaller storage programs, an SPI worth of 92% or extra corresponds to effectivity class A. For storage programs as much as 10 kW, an SPI worth of at the least 93.5% is required.

On common, system effectivity has elevated in each measurement courses since 2018, however the researchers nonetheless see placing variations between programs accessible in the marketplace. For instance, the general losses of the much less environment friendly merchandise had been greater than twice as excessive in comparison with the highest storage programs. Producers additionally offered effectivity information for 284 merchandise available in the market survey.

The researchers used an instance, an AC-coupled system in a residential constructing with an electrical automobile and warmth pump, for example the affect that common effectivity can have on price financial savings from storage. The financial savings potential outcomes from the averted grid buy of electrical energy at €0.32 ($0.34)/kWh, and a feed-in tariff for rooftop generated energy of €0.065/kWh.

On this instance, customers with out a PV system must buy 9,363 kWh per 12 months for €3,000. A ten kW PV system with out battery storage permits for financial savings of €1,360 per 12 months. Including battery storage of 10 kWh and an AC system utilization price of 85% will increase this annual saving to €1,950. If the system utilization price is just 65%, that’s €120 a 12 months much less in your pockets.

The AC system utilization issue is the ratio of the AC output of the battery system to the AC vitality enter. The system utilization issue thus consists of standby consumption and winter trickle charging. “As a rule of thumb, you possibly can say a superb AC-coupled lithium storage system will get 80% to 85%,” says HTW Berlin’s Johannes Weniger. Which means that of 1,000 kilowatt-hours of photovoltaic electrical energy that flowed into the storage system over the 12 months, the shopper receives as much as 850 again. The remaining kilowatt-hours are losses, or must be offset in opposition to the grid buy of the storage system. In much less environment friendly programs, solely 650 to 700 kilowatt-hours may be successfully used.

Whereas the AC system utilization issue instantly describes the vitality losses, the SPI is an financial parameter that additionally takes into consideration electrical energy costs and compensation and is used to make DC and AC programs comparable. If the financial savings within the instance with an excellent system are round €2,055, and the SPI of the true system is 95%, solely 95% of the best worth of €2,055 may be saved; i.e. the beforehand acknowledged €1,950. One proportion level drop to the SPI correlates with €20 much less income per 12 months on this instance. That won’t sound like a lot, nevertheless, with an commentary interval of 10 years for a storage system, it’s already €200. With an SPI distinction of 5%, it provides as much as €1,000 over 10 years. For conditions with totally different consumption and dimensions, nevertheless, absolutely the figures differ from the instance calculation.

System costs

The potential financial savings are offset by the funding prices, that are in the end mirrored in saved electrical energy price. In response to an analysis carried out by RWTH Aachen College, the common value for a residential storage system between 5 and 10 kilowatt hours in 2021 was round €1,000/kWh, together with energy electronics and gross sales tax. Costs had thus fallen by round 8%, based on RWTH. Whereas this determine for residential storage beneath 5 kWh was €1,400, programs bigger than 10 kWh had a median value of about €870/kWh.

That is primarily based on information from 2021, which doesn’t but mirror worsening provide chain circumstances this 12 months. Within the pv journal market overview, we collected value information from April 2022 and in contrast it with that of earlier years. Power Depot Swiss, ET Photo voltaic Energy, neoom and Tesla have given us non-binding value suggestions for publication, and we’ve got acquired private system costs from 5 different individuals. For a lot of different programs, we’ve got decided a practical gross sales value by way of our personal analysis, typically together with the opposite essential elements for the system, similar to an acceptable vitality supervisor, an vitality meter or cabling, and considering a corresponding installer margin. We solely take into account whole programs – that’s, programs consisting of batteries and inverters. So as to make hybrid inverters and battery inverters comparable, we’ve got deducted a power-dependent lump sum for hybrid inverters, which corresponds to the worth you’ll have when you additionally linked a photo voltaic generator. For AC programs, a further photo voltaic inverter can also be required.

The typical product sales value per kilowatt hour for 135 programs was €956, with a variety from €453 to €1,855. The vary will also be defined by the totally different rated outputs and functionalities. For instance, it normally prices additional if a system is to have emergency energy functionality. Final 12 months, we calculated a median value of €896 on this method. So the common value has risen by 7%. Nonetheless, since electrical energy costs have additionally risen sharply, the affect on the financial system is prone to be small.

To have the ability to assess the financial system as compared, we’ve got calculated electrical energy storage prices utilizing the costs and the knowledge offered by the producers on guarantee circumstances. That is the price of one kilowatt-hour of electrical energy that’s saved and retrieved. We assume 300 cycles per 12 months. The result’s a worth of what it prices to retailer and retrieve electrical energy underneath optimum use.

Service life

We base the price of electrical energy for storage on the assured service life, for which a quasi-standard has been established. 97% of merchandise that embrace batteries supply 10-year warranties. Alpha ESS affords 15 years, and the remaining supply 5 years or have chosen to not specify. For 90% of merchandise, producers assure 80% remaining capability on the finish of the guarantee interval. Senec affords 100%, the remaining enter the race with 70%, or have waived extra exact specs.

Often, higher guarantee circumstances apply in Germany than in different European international locations because of the subsidy tips. For 164 programs, the producers supply a full system substitute as an alternative of a present worth substitute, although this doesn’t imply that the producer is obliged to ship a brand new system. In any case, it’s advisable to learn the precise wording of the guarantee textual content. Full substitute ought to imply that the shopper can function a functioning storage system with greater than 80% capability till the guarantee interval expires and doesn’t simply obtain compensation for the residual worth.

Taking all these parameters into consideration, the imply value of our 135 quotations is €0.38/kWh of saved electrical energy till the tip of the guarantee interval. The typical value has thus elevated by 9% in contrast with final 12 months.

The most affordable saved electrical energy price, based on the graph, is €0.18/kWh for Goodwe’s 5-kilowatt, 15 kilowatt-hour system. A standard mixture of roughly 10 kW of output energy and 10 to fifteen kWh of capability is priced from €0.23/kWh of saved electrical energy for producers from the far east, and from €0.30/kWh amongst western producers. Nonetheless, these comparisons should all the time take note of that the totally different functionalities, particularly with regard to sector coupling and emergency energy functionality, will not be taken into consideration. Neither are attainable variations in effectivity. Right here, the calculation is predicated on the idea of an excellent, loss-free system, since, aside from the programs taking part within the storage inspection, the effectivity can’t be estimated. The highest three programs from this 12 months’s HTW evaluation are €0.37 and €0.38/kWh.

There may be principally no change within the economics of battery storage in comparison with earlier years. If the electrical energy buy prices for a family are €0.33/kWh, and one is compensated €0.07/kWh for photo voltaic electrical energy fed into the grid, the storage system can solely contribute positively to the return on funding if the saved electrical energy price is beneath €0.24/kWh. Nonetheless, if we assume that the storage items last more than the guarantee interval, for instance 15 years, the prices we calculated are diminished by one-third.

Moreover, along with assembly customers want to contribute to the vitality transition, storage supplies electrical energy value certainty. If one assumes that electrical energy costs will rise, one also can settle for larger saved electrical energy prices from an financial viewpoint. Nonetheless, one can solely actually assess these results in a extra sophisticated situation that additionally takes the tax into consideration. Shoppers must take into account whether or not the hassle is value it, since ultimately it’s normally no more than plus/minus €100 per 12 months that make the distinction by way of financial effectivity in absolute phrases. No matter whether or not one optimizes economically, or for self-sufficiency, getting the system dimensions proper have to be a major concern.