Energy Storage in Batteries, Super Capacitors & other Technologies
All customer should understand that commonly Energy Storage is there to provide Energy from Sunset through to Sunrise & through extended Bad weather, this applies to Everyone living Off-Grid, and the smart ones will have a Uninterrupted Power Supply (UPS) Inverter that Automatically starts a Gen-set (AGS function) when the Energy Storage voltage gets to a pre-set voltage.
Those Grid-connected, have the option to import power, however without energy storage the customer will commonly be paying through the nose for the Energy they consume that is not Generated from Solar or Wind etc.
If a Retailer tells you Batteries are currently to expensive & takes to long to payoff. Walk away & shop around !
The main reasons behind that statment is either there profit margin is high, or commonly most Solar Retailers push to sell you an over-sized Solar system, as there main focus is to get YOU to sign over YOUR 10 years of "Small-scale Technology Certificates" (STC=REC), NB: 6kW solar REC Credits equates to *$3'500~$4'000 depending on your location, Not bad profit for what should only take a Day to install 14x 435W or 18x 330W solar panels!
Anyone can install a Micro Power Grid, however if you intent to claim the Government Renewable Energy Credits (REC's), the CEC (clean energy council) require an accredited CEC installer to inspect & pass your system. NB: All accredited CEC installers are certified electricians!
How does Energy Storage work ?
Energy produce via Solar, Wind or Aqua generation should be firstly Wired into a Hybrid inverter(s), Inverters first provides energy to your premises and then any excess energy, is Programmable to be sent to charge your Batteries, via Battery Management System (BMS), then once charged any excess energy can be sold via a P2P Energy Trading platform, or exported as a Feed-In-Tarrif (FIT) via an energy retailer.
Charged batteries sit idle ready for Bad weather or sunset, where the stored energy is then used to power your premises until Sunrise, for solar generation again.
Battery storage systems all have different size footprint, capacity, efficiency and cost per kWh, the best battery systems will provide good value for money and last many years past there guarantee period and cycle life, allowing you benefit long after passing the investment break-even point, from there onwards it will be all savings!
We believe the New bread of large Super Capacitors (SC) Modules is the Future of Energy Storage, these are is the Future of Energy Storage for Residential & Commercial industry.
What size battery is require to become Energy Independent or go Off-grid ?
The Simple Two Options are;
- The Minimum Energy kWh Storage should be What you Consume Between No Generation, Until the Start of Generation, Commonly when Solar start Generating again the following day!
- The other option is to Purchase enough Energy as you can afford, to either Last 24hours or for Days!
All that is largely dictated by your Daily energy consumption and length of Energy Storage required.
The minimum energy storage capacity should be what you consume between Sunset to Sunrise, obviously the larger capacity the better as that greatly extends the life of most battery, OTHER than Super Capacitors Energy Storage Modules have a 100% Depth of Discharge (DOD) without Damage.
This is a good FAQ document on Battery Sizing to read (.pdf)
Example: If your premises consumes 15kW of energy/power per 24hr day, and 5kWh between sunset to sunrise, then a 5kWh battery would be smallest, where a 15kWh battery should provide nearly 24 hours power security or greatly assist during sustained bad weather. Additional energy, can always be generated using a small cheap $900 Gen-set to totally black-out proof your premises, if that is your goal.
No matter what battery storage system you purchase, you should Calculate the following;
- The Battery cost per kW: The less you pay for quality batteries the quicker the break-even into profit period is accomplished.
- Battery Life: Is calculated using the manufacturers energy Throughput or Cycle life figures;
- Throughput: If the manufactures energy Throughput is 55'000kWh ÷ 15kWh usable battery energy = 3'666cycles ÷ 365days = 10years.
- Cycle Life: If the manufactures Cycle life is 3'500 times ÷ 365 = 9.6 years.
NOTE: There is only one battery on the market that guarantees 30'000+ Cycle life, these are Super Capacitor (SC) batteries.
There is a New Commercial Thermal Energy Storage Technology (TESS), called 1414° TESS unit, the directors of the company have stated "it will be 1/10th the cost of large Commercial Energy Storage solutions like TESLA". This system would be very suitable for storing energy spillage, what would be normally wastes energy, and be very suitable for Community Energy!
If you already have Solar: You are way ahead, as your break-even point to re-coup your Battery investment will commonly be between 1~3 years depending on the kWh battery capacity!
So, remember when investigating in a micro grid, you need to purchase a Hybrid Bi-directional inverter (not a solar inverter), Hybrid inverters are compatible with variable input voltages, and cost from $900~$6'000 depending on the brand and kW rating, if you intend to operate 3 phase power, you can purchase single 3 phase inverter or three separate single phase inverters, depending on what you are trying to accomplish.
The latest energy storage technology are Dry-cell Graphene Super Capacitors (SC) Modules, they also have the highest Energy Density of 55Wh/kg, and come with a Cycle life of 50'000 times or 12 years guarantee.
Nickel Iron NiFe batteries provide the longest proven cycle life with no likelihood of failure from fire & explosion, and cost $550 kWh.
Lithium-Iron phosphate (LiFePO4) batteries offer lower energy density and also cost $550kWh, these batteries are widely used in electric tools, medical equipment, and other roles.
LiFePo4 chemistry offers a longer cycle life than TESLA lithium-ion batteries. LiFePO4 batteries have a very constant discharge voltage, where each NiFePo4 cell voltage stays close to 3.2V during discharge, until the cell is exhausted. They allows the cell to deliver virtually full power until discharged, and simplifies or even eliminate the need for voltage regulation circuitry.
TESLA's Lithium-ion technology (is Not Lithium-Iron) can pose unique safety hazards since the TESLA battery contain a flammable electrolyte and may need to be kept pressurised. An expert notes "If a TESLA battery cell is charged too quickly, it can cause a short circuit, leading to explosions and fires". Because of these risks, testing standards are more stringent than those for acid or electrolyte batteries, requiring both a broader range of test conditions and additional battery-specific tests. There have been battery-related recalls by some companies, including the 2016 Samsung Galaxy Note-7 recall for lithium-ion battery fires.
Without prejudice, we highly recommend Lithium Iron Phosphate (LiFePo4) and Nickel Iron (NiFe) batteries, as they are the Safest & Cost less per kW, where NiFePo4 have the lowest cost per kW of under $550kW, closely followed by NiFe that have a proven track record and last over 30+ years, with some lasting over 100yrs, NiFe batteries don't use Lead or Acid, they use a cheap & readily available Electrolyte composed of Potassium hydroxide and Lithium hydroxide, that is reported to last minimum 7~10+ years, and when the electrolyte need replacing it only cost 5% of the battery cost, electrolyte replacement refreshes the batteries for the next 10 years !
Nickel Iron (NiFe) battery Electrolyte:
- Potassium hydroxide (1.2g/cm3) is an inorganic compound with the formula KOH, and is commonly called caustic potash.
- Lithium hydroxide (20g/L) is an inorganic compound with the formula LiOH. It is a white hygroscopic crystalline material. It is soluble in water and slightly soluble in ethanol, and is available commercially in anhydrous form and as the monohydrate (LiOH.H2O), both of which are strong bases. It is the weakest base among the alkali metal hydroxides.
As a long term Investment, there are only a few battery types that provide long term reliability, in the following order, Nickel Iron batteries, NiCd batteries (download.pdf), and possibly the new Australian RedFlow bromide batteries(worlds smallest Flow battery), Tesla Powerwall-2 Lithium-ion batteries, all are able to be used for Residential & Commercial applications.
NEWS: In January 2018 an Australian company 1414° degrees introduced a "Molten Silicon Energy Storage System" (Not a battery). This is a Commercial 10MWh Thermal Energy storage system (TESS). Currently there smallest unit is 10MWh system, with an approx. footprint size, of a 40' shipping container and twice as wide, only designed for Large scale applications (250+ homes), a 1414° 200MWh system is the size of a two story building, currently these storage systems are Not for households, however it is claimed that a 10~50kWh system, if developed will only require 70cm3 for the molten core of Silicon (Si).
Super Capacitors (SC) built for Energy Storage:
Super Capacitors (imag-1 image-2 image-3) are the latest in Energy storage devices in 2020, although SC Technology is more expensive per kWh they make a great addition to any existing energy storage system.
NB: Super Capacitor can be wired in Parallel as long as both are the Same DC voltage, It is NOT recommended to wire SC Modules in Series
DC Voltage can vary from 12V up to 750VDC, New Dry-cell Super Capacitors banks is NOT a chemical battery as such, Super Capacitors can Instantly release the total energy stored, unlike a conventional batteries that have 60~80% lower DOD, and restrictive energy release!
So why would we use a Capacitor bank ? Well, if say a Water Heater, Oven or equipment that requires high amps to start, then instead of placing the Initial High load on your battery bank, the combination of Super Capacitor & Battery bank simply Shares the Load/Draw of power, eliminating the load on your batteries, thus extending the life of your batteries, and Super Capacitors Charge back-up in a matter of a few minutes, compared to batteries, thus SC are ready for work first.
Charging Batteries & Super Capacity Storage:
Besides solar, wind or Hydro, an inverter with AGS (auto-generator-start) function, does NOT really require a Generator larger than a 3.7KW as that is what the State Grid supplies to all single phase connections.
A cheap silenced 3.6KW ($850) Gen-set is and most economical methods to instantly increase your power production, Gen-set with starter motors will be automatically started by an inverter with AGS function.
Remember: Whilst a fuel generator is triggered to start, the BMS (battery-management-system) will first supply power to the premises, and obviously all spare energy not being consumed will be charging your Energy Storage system, this way very little fuel is wasted, most generator can be programmed to automatically start & shut-down as required, be it for just a short time several times a day or to just operate long enough to simply charge the batteries to get you through until sunrise.
Can I use a Battery bank to load-shift ?
Yes, battery storage connected to the Grid allows households without Solar, to take advantage of cheap off-peak electricity prices. The idea is to charge the batteries during off-peak times, and then use the stored energy during peak times. This is known as Load-Shifting – But it doesn't make much financial sense unless there is a substantial difference between the day and off-peak power rates.
All batteries can off-set whatever kW of energy they store, for example, a premises with a 10kWh battery bank, consuming 10kWh day, can charge the batteries in approx. 4 hours @$0.28 to $1.12 per day using the inverters' 120A Battery Charge circuit (or power from a generator can be used), so charging the batteries at off-peak rate of $0.07 c/kWh cost $0.28 per day. This gives a saving of $0.84 per day, or around $310 per year.
Super Capacitors (SC) Energy storage technology is superior to all other energy storage technologies, including NiFe, LiFe, LiFePO4, and obviously Cave-Man Lead Acid batteries!
Will battery storage become cheaper ?
Yes, the costs of battery used for energy storage have been falling at a rapid rate and forecasts are for this trend to continue as more and more households adopt them. For example, the cost of battery storage fell 14% every year on average between 2007 and 2016 and it's expected that prices will halve again within the next five years.
As of January 2021, single unit purchase Calculate Cost per *kWh;
- 10.24 kWh Lithium iron phosphate (LiFePo4) battery cost $4'550 ÷ 10.24kW =$445 per kW.
- 9.60 kWh Nickel iron (NiFe) battery cost $7'650 ÷ 9.60kW =$800 per kW.
- 8.50 kWh Super Capacitor (SC) Graphene Modules cost $8'160 ÷ 8.50kW =$960 per kW.
- 10.0 kWh RedFlow Bromide battery cost $10'000 ÷ 10kW =$1'000 per kW.
Clearly leaving LiFe & NiFe batteries well ahead of thee rest in price and proven reliability, with NiFe reported "as new" after 30+ years!
Solar panels are also getting cheaper, with a 75% drop in price over the past five years.
With the global market for solar panels and battery storage expected to grow ten-fold by 2020, the demand for battery systems like Nickel Iron (Non acid), RedFlow (Bromide) etc. should have flow-on effects on prices as economies of scale kick in.
* approximate figures.