This page will summarize what solar power storage is, current applications, its importance for further solar power expansion, and highlight the most prominent battery storage companies.
As the name implies, solar power storage is simply the storing of excess solar power in a power storage system.
Solar power battery storage has enabled access to the sun’s energy after sunset for many decades now. This has traditionally been accomplished via deep cycle lead acid batteries. While lead acid batteries are still commonly used in conjunction with solar panel systems, they will not be the focus here. Instead, lithium-ion batteries will be discussed due to their many advantages. As costs continue to decline for lithium-ion battery storage solutions, they are predicted to increasingly become the go-to power storage option.
Home battery storage systems can be added along with a new solar installation, after a solar installation, or even without a solar panel system. For the purposes of this page, only situations where solar is present will be considered. There are two primary setups for solar plus battery storage installations; DC-coupled systems and AC-coupled systems.
DC-coupled storage systems are the setup for new solar panel systems. In this type of install, a charge controller regulates the DC power from the solar panels to prevent the batteries from overcharging. DC coupled systems are typically less pricey because only one inverter is needed. Here’s a diagram –
AC-coupled systems are common for existing solar installations. One of the reasons for this is that the existing connection from the solar panels to the inverter does not need to be rewired. Instead of needing a charge controller, the grid-tied inverter controls the DC flow. In an AC-coupled system, the critical load subpanel manages current from both the grid-tied inverter and the battery-based inverter.
There are currently a few applications for a residential home energy storage system. Here’s a list of the primary ones. Solar power storage systems can –
- Provide emergency back up power when there is a loss of utility power due to inclement weather.
- Enable peak energy shaving – utilizing stored energy instead of using expensive grid energy during peak hours.
- Help move owners closer to a more sustainable and self-reliant situation.
The solar plus storage chart offers a visual representation of the benefits offered to homeowners utilizing this power setup. There’s much to discern from this chart, so let’s break it down step-by-step.
- Load without Solar + Storage System (represented by the turquoise line) – is the average daily electric usage and pattern for those who do not have solar or battery storage. Load simply means electric usage. As people get home from work around 5:00 pm and lasting until 9:00 or 10:00 pm (peak time) usage goes up considerably as well as their monthly electric bills (due to many utilities charging extra for electricity used during peak hours. Also known as demand charges).
- Load with Solar + Storage System (represented by the green line) – On the other hand, those with solar coupled with energy storage systems can get most of their energy through solar and their battery systems. Most peak energy usage charges are avoided by keeping utility energy usage very low.
- PV Generation (the yellow line) – is the typical electric generation provided by a solar panel system during a given day. As can be seen, a pv system is providing more energy that is being consumed by a home. The excess energy is used to recharge the battery system.
- Battery State of Charge (the black line) – the energy storage system begins to be recharged late in the morning and is at high capacity by sundown, when its energy is needed. Assuming no major electric loads, an average sized battery storage system can provide hours of electric capacity.
Here are the primary advantages of lithium-ion batteries over lead acid.
Lithium-ion batteries –
- Have about 4 times the energy density compared to lead acid.
- Last about 3 times as long.
- Require no maintenance or venting of gasses.
- Require much less space due to higher energy density.
- Are much more reliable.
- Are fully scalable.
- Are fully recyclable.
The energy storage market is poised for major expansion in the coming years. We are at a point in time at which the pricing for energy storage is starting to become economically viable. The technology is there, now the cost needs to catch up.
A pricing parallel can be drawn to the solar panel industry. For decades now, solar pv modules have been able to produce sufficient energy efficiency. What held the adoption of solar power back was primarily the cost of solar panels. It’s the current low price of solar panels that has propelled the recent amazing growth in the solar industry, not incremental improvements in energy output.
While future improvements to lithium-ion technologies will occur, no major breakthroughs are needed. Much like the solar panel industry, a decline in the cost of energy storage is what will bring massive growth to this market.
Current low end retail pricing for lithium-ion energy storage is close to $400/kWh. This pricing leads to energy close to $0.15/kWh over the life of the system. This is just for the battery system. The necessary inverter will have already been purchased if the storage system is being added to an existing solar panel system. This pricing is already attractive in Hawaii, California, and some states in the North East.
In the not too distant future, the average homeowner will find it fairly cost effective to be almost completely energy self-reliant via a solar plus storage system as pricing for energy storage continues to fall.
While there are likely to be many more battery companies entering the marketplace in the coming years, only the most reputable companies will be highlighted here. The following energy storage companies, listed in alphabetical order, are poised to offer the most value in terms of their battery offerings.
Those interested in battery storage solutions through Solar Power Now will be offered at least one of these products through my installer network. Fill out the main form on this page to get started.
To sum up, the solar power energy storage market is about to experience a rebirth and considerable growth period as it transitions from lead acid to lithium-ion. Energy storage systems can be added both before and after a solar panel system has been installed. These battery systems can offer peace of mind to homeowners during a power outage, help them avoid peak electricity costs, and provide much more energy self-reliance. Costs will continue to fall for energy storage while consumer choice will increase as more energy companies make their offerings nationwide.
