One size does not fit all: A conversation about energy storage to accompany PV generation with SOLON Corporation R&D Director Bill Richardson

William Richardson
William Richardson

William Richardson heads Research and Development (R&D) for SOLON Corporation, where he oversees component testing and product development, as well as strategic management and evaluation of new technologies for the North American market.

Prior to joining SOLON in 2008, Bill worked for Tucson Electric Power where he developed a profound understanding of the challenges inherent in large scale adoption of photovoltaics into the grid. In 2009, Bill implemented SOLON’s North American Outdoor Testing Facility, where next generation module, tracking, and systems integration testing is conducted.

Most recently Bill is overseeing SOLON and Tucson Electric Power’s energy SMRT site – a utility-scale energy storage management research and test site attached to a 1.6MW single-axis tracking system, that will evaluate multiple storage technologies, create and validate total system economic and performance models.

This project will ultimately provide SOLON the expertise to provide comprehensive PV, storage, and control systems to the utility market.


Solar Server: Does SOLON Corporation have basically the same focus as SOLON SE, or do you have different priorities?

Bill Richardson: We address different markets. The whole reason that SOLON exists in the U.S. is to address the U.S. market, which is different than the European market. But it is still similar values: high quality product, turnkey systems, all of the solutions.

This last year SOLON Corporation was awarded 2010 Generation Supplier of the Year from PG&E, and that includes gas, coal, everything; and they picked a PV supplier. So that's really good for the industry.

We've got a few projects we are currently installing. In California for PG&E we have 15 MW- AC going in, we have 18 MW-AC for APS being installed in Gila Bend, Arizona. We finished 1.6 MW for Tuscon Electric Power (TEP) the first of this year.


Solar Server: That's the PV plant at the University of Arizona Science Park?

Bill Richardson: Yes, the 1.6MW that we built for TEP last year, that is the one that we are going to attach the storage site to.


Solar Server: Can you tell me a little bit more about that R&D storage center and what its goals are, specifically?

Bill Richardson: PV is getting bigger and bigger, it is getting higher penetration. We have discovered that utilities are concerned about the effects of intermittency of PV in these large scale projects.

And so we are looking out into the future, and saying OK, if that is something that is going to have to be addressed, if the utilities want control of the PV plants, then as a system provider we should be experts in giving them that control.

And that is going to require storage. And the way that you become an expert at installing, integrating and controlling storage is you install, integrate and control the storage. You have to actually do it. So that's what we are doing.

To do that, of course, you want to start at a small scale, so you learn where not to make mistakes at 100 kW instead of 100 MW. So that's when we came up with the idea of this energy SMRT site, it stands for energy storage, management, research and testing.

The energy storage research and testing site will be attached to a 1.6 MW PV plant built by SOLON and owned by TEP
The energy storage research and testing site will be attached to a 1.6 MW PV plant built by SOLON and owned by TEP

So we went out and found a utility partner, TEP, who also has a similar interest in storage, and how it integrates with PV, and how it affects their grid, how they control it and what are the benefits they are going to get out of it.

And we found another partner in the University of Arizona. They are interested in demonstrating some prototypes that they have for storage, namely compressed air.

Also, at the University of Arizona are groups like their systems engineering group, and they are interesting in perfecting their energy management system, developing algorithms that can take a look out at the grid, see what the grid rate is right now, what the state of charge is for the battery, all the different factors, and make a decision for whether that battery should charge or discharge.

Another group at the University is the economics department which is working on economic models about storage. Of course, everybody makes their models, and their algorithms, but how do you know if they work? You run them. That's what we will do.

We have this storage site, and when it is all built, we will be able to validate them, run them, gather all kinds of information for us and the folks who provide storage technologies .This information can be used as support for the banks and the utilities.

And while all that is happening, we get the experience of installing these various technologies and giving that control to the utility partner, and getting feedback.


Solar Server: So in terms of specific technologies, are there any technologies that stand out to you as being particularly promising for accompanying PV generation? I know that there are issues with some technologies being more appropriate for long-term storage, others being more appropriate for quick shifts in demand. But when you factor all of that together, which are the ones that really stick out?

Bill Richardson: What you said is exactly right - there are some things that are good for short, there are some things that are good for long.

There are ten other external factors at least, like climate, geography, local policy, generation portfolio of the customer: What makes sense for them? It is going to be different for every location, for every customer. That's why it's not one winner that we necessarily see.

But which ones are we interested in? We went to our customer and said: "What are you interested in?" Because that's what we want to be good at putting in. That is why the compressed air tied in nicely. TEP told us, “compressed air is interesting”.

Ostensibly, you are putting in this storage, attached to your PV site to address intermittency. But it happens to be that there are all these other value streams that the utility can get from storage. So we don't have to look at it as just this expense, this burden that has to be put on PV, because it turns out it has a much higher value to utilities, when you can quantify what those values are.


Solar Server: So compressed air - what about lithium-ion battery technology?

Bill Richardson: So you got it - that's the next one that is going to go in. The first one will be compressed air, then next will be lithium.

And after that, we have two more technologies that TEP is looking at which they are going to put in. It is slotted to go in, but I don't think they've made a precise decision as to exactly what technology is going to go in, and what company is going to provide that technology.

But lithium is quicker - maybe expensive. It all varies so much. I know you want me to peg one specific technology as a winner.


Solar Server: No, not really; I am just interested to hear which ones you are interested in and why.

Bill Richardson: Where this site is, in the desert Southwest, it is where a lot of PV is going in. As I've mentioned before, external factors that affect which technologies goes in: It's hot, it's hot in Arizona, it's hot in the desert Southwest. So is that heat going to affect lifetime of batteries - or whatever storage is out there? And the answer is yes, depending on what the technology is.


Solar Server: Now, given that in the United States and most other nations that have not put in high concentrations of PV, we are still a long way from PV affecting grid reliability, why are you looking at energy storage at this time?

Bill Richardson: If we don't start looking at this now, then where are we going to be when it comes around? That's SOLON's thing, looking out into the future, what is the next thing? Now is the time for us to become experts on it.

We don't want to wait until storage comes around as what has to be put in place. We don't want to wait for that request for proposals (RFP) to show up that says, we want your PV plus 5 MWh of storage.

When that RFP comes in, we want to say, great, because we've been working on this for years, and we can do it.


Solar Server: Does SOLON Corporation perform any of the R&D work with crystalline silicon modules, or is that done in Germany?

Bill Richardson: I don't know if you know about our global test site network. We have  SOLON Berlin, we have a manufacturing facility in Italy and our US headquarters in Tucson. Three distinct climatic regions.

A few years ago what we did was we built up our global test site network, and that consists of identical test sites in all three of these regions. When I say identical, I mean identical. We have exactly the same tracking systems, we have dual axis tracking, single axis tracking and fixed-tilt. We have all the same measurement boxes, all the same inverters. Even our cable lengths are precisely the same.

This allows us to test the same thing, for example the same crystalline module, in three different sites, and see where it is most appropriate.

SOLON's standardized Velocity system technology is designed to meet the specific needs of utilities, reducing total cost of system ownership.

SOLON's Velocity MW utility-scale solar systems are built up from identical, 1-megawatt clusters to achieve high energy output with known performance.

Solar Server: Are there any technical aspects you are working on in terms of improving efficiencies or other aspects of improving your crystalline silicon modules that you want to talk about?

Bill Richardson: There is this a phenomenon called potential induced degradation (PID). SOLON released a paper on it at Valencia last fall, I spoke about it at an NREL event earlier this winter, It is an issue that has been affecting a number of plants in Spain.

And it happens when you have a negative bias on your modules - which you see in Europe, because you have a floating ground. Half the string will be positive, in relation to ground, half the string will be negative in relation to ground.

On some fields out there, they are discovering that these strings that are negative relative to ground, some portions of it, the modules are degrading. The power output is degrading.

So SOLON went out and figured out why that is. We were able to reproduce it in the lab, on a cell level, and we were able to reproduce it on a module level. And then we went to our suppliers, and we were able to fix it on a cell level, and we were able to fix it on a module level.

Basically by using the right materials, in the right way, we can make PID-proof modules, modules that will not have this effect.

OK, so that is in the lab, and how do you make sure that happens everywhere? That is one of the things that we are testing on the Global Test Site Network. It turns out things like humidity really affect it.

So we are able to take modules that are PID-prone, basically modules that we build because we know this combination of materials will basically create a module that could get this potentially induced degradation.

And then we build a string of PID-proof modules. And we can put both of these strings up at all of our test sites. And see how they react in different places. Maybe in the arid Southwest you don't have to worry about it. Maybe you do, when monsoons come around, it gets humid. So that is what we are looking at.

And if we can prove that these materials make these modules PID-proof, now nobody has to worry about that.


Solar Server: Is there anything else that you want to tell me about the R&D activities at SOLON that we haven't talked about?

Bill Richardson: You could look at Europe for some of the products that we are putting out to get a feel for some of the development that is happening within the SOLON Group. You'll see a lot of new rooftop products and solutions.

And this storage that we are doing, I am looking of course at utility-scale, because what do we do, here in the states, we build massive utility scale plants. Storage on a residential scale doesn't necessarily make sense in the United States.

But in Europe, our R&D is looking at storage on a residential scale. Because of the way that the tariff works there, now it can really make economic sense, with a small battery attached to your house, you can see it at every turn. So our R&D groups are working in concert, in parallel, but also on different paths, each addressing the unique market that they are in.


Solar Server: So to talk about storage a little more - you've looked at compressed air, you've looked at lithium-ion. What are the next two technologies?

Bill Richardson: The next to go in - TBD - TEP has not decided, I think they are looking at a few different possible solutions.

I mean there are the front runners - of course sodium sulphur, which is reasonably well established, so maybe its not as interesting for the utilities to put that in a test site. There are flow batteries, those I think got a bad reputation some years ago, but seem to be coming around, we are seeing a lot more of those coming on the scene.

So I spoke yesterday, and after the presentation (at Intersolar North America), I was inundated with folks handing me their cards, about the next technology they want to put out there. Maybe its too early to say, perhaps out of that group of people maybe we'll find a few more interesting partners.

This thing is big. It's not just enough space for these four technologies, you've got a ton of space out there to put all different kinds of storage systems in, so we are always looking for new partners, partners who want to come in and demonstrate something, or study something.  We’re always looking for new people to work with on this.

The more people that come in, the more experience that we get, the more things that TEP and the rest of our partners gets to look at.


Solar Server: So why put in energy storage when you can just build another natural gas peaking plant?

Bill Richardson: Exactly something I pointed out yesterday. When I mentioned all those external factors, one of those is the cost of fuel. If fuel is cheap, and I'm a utility, and I know how to build natural gas plants, then maybe that's just what I do.

But it's going to be a lot harder to build a natural gas plant in the middle of a neighborhood somewhere, than it is to maybe drop in a 20 MW flywheel. So there are more factors there - permitting, location...

Every single application is going to call for a different solution. There are so many moving parts. You can't pick a winner; you don't know what's necessarily coming, so you just have to be ready for everything.


Interview conducted in August 2011 by Solar Server International Correspondent Christian Roselund