Why store solar energy?

Solar photovoltaic generators can generate electricity as long as they are exposed to sunlight. Especially at noon, when the amount of solar radiation is highest, the power generation reaches its highest. However, typical households use electricity primarily in the morning and evening. If all family members are working, the solar power generated at noon often must be fully fed into the grid and cannot meet their own needs. Power storage (also called battery storage) solves this problem and stores the electricity generated during the day in between. In the evening and early morning, if the photovoltaic plant is not producing energy, then it can simply draw electricity from the mains. Energy storage takes its place to meet demand.

The principle of energy storage power supply

How to increase self-consumption of electricity through electricity storage?

If you install a photovoltaic system in a single-family home, you can use approximately 30% of the solar power yourself. The remaining 70% is fed into the power storage. As energy storage increases, self-consumption reaches 50%-80%. As a result, you will be more independent from energy suppliers and be able to better utilize your capacity while saving on electricity costs.

Power supply changes when installing photovoltaic systems and energy storage power supplies

Can power storage save more C02?

With power storage, less power is drawn from the grid. Electricity is only about 50% to 60% renewable energy, while solar panels can produce 100% renewable energy. So with power storage you always save CO2.

Electrical storage produces CO2 emissions only during the production process. The Heidelberg Institute for Energy and Environmental Research estimates that producing 1 kilowatt hour (kWh) of storage capacity will release approximately 125 kilograms of carbon dioxide. This number is expected to decline further as technology advances. Each kilowatt hour of electricity produces about 420 grams of carbon dioxide, and each kilowatt hour is not obtained from the grid but from electricity storage, so 420 grams of carbon dioxide is saved, so the carbon dioxide released during the production process is usually available within one to two years. compensate.

Example: CO2 balance of 8kWh battery storage, 4000 kWh household electricity consumption

For a typical 8kWh battery storage for a home, assuming a storage capacity of 125kg per kWh, approximately 1,000kg of CO2 will be released during production. Assuming an electricity demand of 4,000 kWh, 8 kWh of electricity storage to increase self-consumption from 30% to 65% would require 1,400 kWh of electricity from the electricity supplier. Since one kilowatt-hour of electricity produces approximately 420 grams of carbon dioxide, over a year this saves over 588 kilograms of carbon dioxide. After 1.7 years, manufacturing emissions have reached equilibrium. The carbon dioxide emission reduction over 20 years is 11.7 tons.

CO2 emitted by producing an 8 kWh storage: 8 x 125 kg = 1,000 kg

Reduced electricity supply through photovoltaic system without electricity storage:4000 kWh x 0.30 = 1200 kWh

Reduced power supply via memory:4000 kWh x 0.65 = 2600 kWh

Additional current savings through power storage:2,600 kWh - 1,200 kWh = 1,400 kWh

Annual CO2 savings from electricity storage:1,400 x 0.420 kg = 588 kg

Year before offsetting CO2 emissions:1000kg/588kg=1.7

CO2 emission reduction 20-year operating life= 588 kg x 20 – 1,000 = 11.7 tons of CO2

How much will battery storage cost in 2024?

The storage capacity of a typical single-family home should be between 5 and 15 kWh. While the average cost of battery storage capacity of this size ranges from €700 to €1,000 per kWh, smaller memories are relatively more expensive than larger solar cells.

Small memories with a storage capacity of only 5-7 kWh cost approximately €4,000 to €6,000. On the other hand, slightly larger storage with a capacity of 8-10 kWh costs between €6,000 and €8,000. A large storage device of about 15 kWh will cost you up to 11,000 euros.

Manufacturer choice is also a key differentiator. While manufacturers such as Huawei, RCT or BYD offer particularly cheap models, other memories are more likely to enter the high price range.

How have storage prices developed in recent years?

The price of electricity storage has dropped significantly in recent years. The main reason for the decline in storage prices is increased demand and the consequent large-scale production, which makes it possible to produce electricity storage in large factories and under favorable conditions. Not only batteries, but also photovoltaic facilities are becoming increasingly cheaper to produce. While it initially cost 50 cents or more to produce a kilowatt hour of solar power, since 2011 solar power has become cheaper than grid power.

Since then, there has been an increase in the use of decentralized solar power generation locally, rather than obtaining electricity from electricity suppliers. Currently, the cost of generating electricity from photovoltaic power is 11-13 cents per kilowatt-hour. By comparison, the cost of a kilowatt-hour on the grid is about 32 cents per kilowatt-hour today, which is a savings of 19-21 cents per kilowatt-hour. Without storage, a home can typically only use 30% of the solar power it generates. With memory, the self-use rate has increased to 50% to 80%. Therefore, the electricity costs incurred can be greatly saved.

Is a kilowatt-hour of stored solar electricity (including the cost of purchasing the storage) cheaper than electricity from the grid?

Yes, since 2016 it is cheaper than electricity from the grid. As the manufacturing cost of memory continues to fall and electricity prices rise year by year, financial subsidies for using memory to store solar energy are also steadily increasing.

How economical are storage PV systems today?

The economics of a PV system with electricity storage are covered by comparing the purchase price to the income you will receive from the facility over the next 20 years (often the facility may even operate for 30 years or more). Revenues are made up of electricity cost savings and revenue generated from supplying electricity to the public grid. The better the solar energy storage capacity matches the size and power of the PV system, the better it can meet its needs.

Note: The 20-year consideration period makes sense because food compensation is awarded for 20 years. However, power storage can often extend beyond this. Most current battery models have 10,000 charge cycles. Charged 300 times per year, the memory can be used for 30 years.

Photovoltaic systems with memory are economical when:
Income and savings over 20 years of investment > Investment costs

Sample account

A household with a household electricity consumption of 5,000 kWh purchased a 10 kW photovoltaic system with 10 kWh storage capacity for €19,800. As a result, it achieves approximately 77% electricity independence and saves 1,232 euros in annual electricity costs at an electricity price of 32 cents. After 20 years, the electricity cost savings will amount to €24,640.

Savings on electricity bills after 20 years= 5,000 kWh x 0.77 x 0.32 € x 20 years = 24,640 €

In addition, revenue generated from delivering the electricity generated to the public grid is included. Here, the state gives a fixed subsidy per kWh over 20 years, which in our example plant supplies approximately 4150 kWh of electricity to the grid per year.

Let's take our example factory with 2013 installed storage. Here, the equipment operator will receive 37,210 euros over 20 years (average electricity price is 30 cents). However, in 2013, such a device would cost approximately 35,000 euros. Therefore, it does not depreciate over the lifetime of storage.

€23,100 + €14,110 = €37,210 > €35,000

By comparison, today's installation will cost our factory €31,371.3 over the next 20 years. However, the plant is more expensive as the procurement cost is only 19,800 euros.

24,640 € + 6,731.3 € = 31,371.3 € > 19,800 €

How big should power storage be?

The size of the power storage depends on many factors. The most important thing is your individual needs, if you already have a photovoltaic system, the size of the power storage you need, also whether you want to be as independent from the grid as possible, or whether you want to reduce your electricity bills. For maximum self-sufficiency, you need a very large memory. However, mid-range memory can only achieve 60% self-sufficiency.

What are the considerations for battery storage and where is it best to place it?

Battery capacity can vary greatly by manufacturer and size. Standard sizes are 1.3 to 1.9 meters in height and 0.5 to 1 meter in width. It is best to place the memory close to the instrument cabinet or inverter.

What technical characteristics do we need to pay attention to in memory?

When selecting a suitable power storage device, parameter specifications are quickly revealed in the manufacturer's technical data sheets. The most important indicators of electrical storage are storage capacity, efficiency and the number of possible charging cycles.

Storage Capacity (also called Capacity) —The amount of energy, measured in kilowatt hours, that can be stored in battery storage while charging. Typical battery storage capacity for a single-family home is between 6 and 16 kWh.

Capacity vs Storage Capacity

Efficiency Level — Efficiency indicates how much energy is lost when storing solar current. At 80% efficiency, 80% of the original delivered energy can still be used after storage. The efficiency of lithium batteries is now very high, reaching 95%-100%.

Number of charge cycles — A charge cycle is a one-time charge, store, and unload, using all storage capacity at the same time. Your power storage should be created for at least 5,000 charge cycles. Some manufacturers, like Sun, even guarantee 10,000 charge cycles.

Just a few years ago, battery storage costs for photovoltaic systems were so high that they were considered a profitable investment. The price of solar energy storage has dropped significantly in recent years as technology improves and mass production increases. This development has also given a significant boost to the number of home storage installations. In 2013, only 5,000 batteries were installed in Germany, and by the end of 2022 there were more than 600,000.

2023 promises to be a new record year. In the first half of 2023 alone, 268,000 new memories were installed. Overall, storage increased to nearly 900,000. It is estimated that by the end of 2023, more than 1.2 million batteries will be installed.

Electrical storage is a store of chemical energy that functions essentially the same as a battery in a smartphone or car. During charging, the battery converts electrical energy into chemical energy through a chemical reaction, making it storable. Discharging causes the process to run in reverse order and converts the stored chemical energy back into a usable electrical current.

In detail, how this works: A battery always consists of two electrodes, an anode and a cathode. The electrode that generates electrons is called the cathode, and the electrode that absorbs electrons is the anode. Photovoltaic systems generate electricity as electrons travel through an external circuit from the cathode to the anode. At the same time, ions also move from the cathode to the anode. At the anode, ions and electrons eventually react with atoms. Discharging does not require electricity, it is the reverse process. The ions return to the cathode and the electrons return to the cathode through the circuit. As electrons move from the anode to the cathode, the current generated can be absorbed.