Storage-Backed Inverters Doing the Same as the Smart Grid

Our guest blogger is Mark Mays, an applications engineer at Outback Power focusing on system design, configuration, field commissioning and troubleshooting of both off-grid and grid connected solar energy systems. Previous industry experience included power quality audits, product development of power quality analyzers, development and delivery of CEU training programs in power quality and electrical troubleshooting for the electrical utility industry, licensed electricians and electrical engineers.

One of the challenges with solar energy has always been storage. Installations produce a great deal of electricity to support a home or business, only to send the excess power back to the grid. This is especially problematic because the peak solar generation period occurs in the middle of the day, when utilities and consumers need it least. This issue is exacerbated by the fact that the cost of photovoltaic (PV) equipment is continuing to decrease, while our collective electricity consumption during nighttime hours continues to grow.

There’s a solution emerging in energy storage-based inverters. Also known as grid-hybrid inverters, they’re equipped with technology that can regulate usage to direct excess power back to the grid or store it if necessary. The grid is definitely getting smart, but it still has a ways to go. Integrating smart, battery-backed inverters can now give system owners some of those long-rumored benefits of the smart grid. The technology woven into the system helps consumers save even more money since no energy produced from solar is wasted.

Grid connection timers built into battery-based inverters can automate the process for users. The timers are programmed to disconnect from the utility grid as necessary. Customers can use the inverters to go off grid during times of day that come with peak surcharges. Ultimately, cost saving has always been an attractive benefit for consumers moving to solar. The evolution of the equipment’s technology has made it easier to see these benefits.

Moreover, excess power produced by the inverter paired with energy storage can qualify end users for rebates or credits from local utility companies or governments. Being able to store produced electricity has put battery-based inverters on the top of customers’ shopping lists, diminishing reliance on the grid during peak times and helping people to manage their energy consumption more proactively.

For years, experts and consumers alike have waited for smart grid technology that is likely still years away from becoming a reality. New features in storage-backed inverters have started to offer some of those features, which deliver benefits for everyone. Aside from a decreased financial burden, storing energy diminishes a utility’s need to operate expensive, wasteful spinning reserves. Peak demand times will always result in a surge in production and use. They don’t, however, have to affect consumers financially to the level they once did. As inverters that use energy storage get smarter, it’s possible to experience smart grid-like benefits today.

8 comments on “Storage-Backed Inverters Doing the Same as the Smart Grid

  1. eafpres
    May 15, 2015

    Hi Mark/Steve.  Thanks for the post.  Aside from the “smart” part, do you have any thoughts of the economics of large batteries for storing solar-derived energy?  In particular, do you think the long-range solution will be batteries such as we have today (lead-acid, Li-ion) or will the application require more advanced batteries still in development?

  2. D Feucht
    May 15, 2015

    Hi Mark,

    Your presentation of what I would call distributed small-scale cogeneration might be more important than it seems to many. The power grid is more vulnerable to failure and even complete collapse (with one EMP bomb or a few well-placed HV transformer snipers needed to do it) than many realize, and having distributed generation and storage is important in surviving infrastructure meltdown.

    What I do not understand about Outback (and also Xantrex) inverter design is why you choose to build what I call “boat anchor” inverters using 60 Hz magnetics when high-frequency ferrites are less massive, smaller, cheaper, and just as reliable if designed right. I just don't get it … Perhaps it is “patent persistence”.


  3. MarkMays
    June 2, 2015

    Hello, D Feucht. I'm afraid I'm not qualified to comment on the tradeoffs of 60 Hz magnetics versus high frequency ferrites. However, our design engineers are always looking at new and better ways of doing things, so maybe high-frequency ferrites or something even better will find its way into our future designs. Mark

  4. MarkMays
    June 2, 2015

    Hello, eafpres1. My take is that lead acid and Li-ion chemistries lend themselves more to smaller, distributed applications while technologies like flow batteries are better suited to utility scale sites. Packaging lead acid technology into utility scale sized batteries would create a size and weight that would be nearly impossible to transport and most likely would have to be built onsite. While Li-ion batteries reduce size and weight over lead acid by 60 to 70 percent, I believe utility scale is still somewhat impractical. I used to be a manufacturer's representative for a flow battery company and visited a utility scale site that was 275kW by four hour (1.1 MWh) battery. The two tanks of electrolyte were each about 20 feet long by about 4 feet in diameter. Not cheap, not trivial, but doable. However, as mentioned in the post, it's not only the capital expenditure of the utility scale battery, but also the infrastructure support costs. If home and business owners are going to install PV on their roofs for later use during peak demand periods when they can go off-grid, the need for additional peaking plants and increased infrastructure to support utility scale storage goes away. Mark

  5. eafpres
    June 2, 2015

    Thanks, Mark.  I would also suggest that flow batteries have a higher potential for more serious problems if damaged or leakage happens.  Industrial / Utility sites can be prepared for this; most home owners would not.

    What do you think about fuel cells in these applications? (i.e. the “storage” is converting water to H2 and O2 and storiing those, the consumption is using those fuels in a fuel cell to deliver the power they need.

  6. MarkMays
    June 2, 2015

    Hello eafpres1. I don't have a lot of personal experience on fuel cells, but some of our customers have used them, where they were used more as demonstration/experimental projects than primary storage. The main reason is the round trip conversion efficiency is quite low, like the single digits or very low double digits. However, they do scale up nicely like a flow battery, and perhaps there have been recent innovations that make them more efficient and cost effective. Mark

  7. ChristopherJames
    October 4, 2018

    I don't want to be one of those maniacs, but I can't help but think that there is a really big conspiracy behind the advent of solar power becoming more of a staple in the power industry. Despite the leaps and bounds that we're seeing in the technology, it remains to see as to whether or not our public utilities will try to find ways to monetize the whole affair so that they can retain their own profitability… It's not about our success but about their earnings isn't it…

  8. Steve Taranovich
    October 4, 2018

    Right Christopher—the consiracy resides at the Power providers

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