Blackout got you powerless? Solar panels alone won’t help, but solar batteries can! This blog explains how battery backup keeps your home running with sunshine, even when the grid goes down. Learn more about solar power and weatherproof your home!
John Maher: Hi, I’m John Maher and I’m here today with Brian Sadler, Vice President at Solaris Renewables, a solar company in Massachusetts providing premium solar and storage technologies with exceptional customer service, and designing, installing and servicing solar systems in Massachusetts, Southern New Hampshire, and Maine. Today, our topic is how solar-powered batteries can help you prepare for power outages. Welcome, Brian.
Brian Sadler: Hi, John. Good to be with you today.
How Solar Panels Work with the Power Grid
John: Yeah, you too. So Brian, if I understand this correctly, standard solar panels, when they’re tied into the power grid, which is how you normally do it (unless you have solar panels and you’re trying to live completely off the grid in some remote area or something like that) you’re not able to provide power to your house during a blackout, even if it was during the day. So, can you explain that and how adding a solar battery to my system would allow me to use solar energy as a backup power source during an outage?
Brian: Sure. That is a common misconception. “Well, I got solar, why can’t I have it all the time? Why does it go down?”
John: “Isn’t that going to power my refrigerator when I have a power outage during the day?” Something like that.
Brian: Right. So just due to safety and code compliance, it’s the inverter, which is what takes the solar panel electricity and make it so our homes can use it, that inverter needs to see a signal from the grid. So being a grid-tied system, it sees a wave, a signal from the utility, that the grid is up. And that tells it it’s okay to continue operating. When that signal goes down because there’s a power outage and the grid is down, for safety’s sake it tells the inverter to shut off, and it does so instantly. And therefore, you’re not pushing power onto the grid and potentially hurting or killing the people that are trying to get the grid back up and running because the flow of electricity, if we think of it like water, it doesn’t discriminate. It goes to the path of least resistance.
And if the grid is down, the wire’s still connected to your home. And if you’re pushing power onto the street, so to speak, or onto the utility lines, there might be someone right in your street that’s trying, that’s working on the grid, and they’re going to get hit by that electricity. So they’ve already shut off what they need to shut off to make sure that there’s no feed coming to that area as they’re trying to work on the grid. And all of a sudden, there’s solar, if this were allowed, there’s a stream of electricity that’s coming on locally that would injure them. So for safety…
John: They don’t have any way at their power company to go, “Oh, your house on that street over there, I’m going to shut off your power while we’re working on the lines outside your house.” They don’t have any way to do that.
Brian: They do have a way to do that.
John: Well, I mean, they can do that, they shut off the power when they’re working on the lines, but then if your solar panels were pumping electricity into the system as well, they wouldn’t have any control over that. But you’re saying that the system is designed such that it shuts off that power to make sure that those people are safe.
Brian: It shuts off. When the grid goes down, the inverters go down. But to your point, there is an additional layer that the utility and fire departments and local town officials know exactly the setup because we have to apply for permits with a design and detailed diagram with all the electricity. And there’s what’s called a rapid shutdown, which is a safety compliance that started in 2015. And what that is, there is a disconnect on the outside of every house that has solar so that the utility can shut it off. But in the event of an emergency, their focus is getting the grid up and running, not running around shutting all the individual solar systems off.
So if they were, when the grid is up and they needed to work on your section of the grid, they will come and shut your solar system off and then turn it back on when they’re done. But in the event of an outage, due to the emergency piece of that, they are going to … The inverters and the electronics of every solar system needs to shut off automatically when it doesn’t see that grid signal. So that absolutely does happen where you lose your solar, so to speak. But if you add a battery system to it, there’s another mechanism, part of that system is to cut you off from the grid. The battery then provides that signal to the inverter, which is how your inverter is able to now stay up and operating.
So typically speaking, it’s an automatic transfer switch and other controls that are set up to interact with your panel and the grid. And when the grid goes down, your automatic transfer switch from your battery system is engaged instantly. It’s usually within milliseconds. So you generally don’t even see a flicker of light or anything disrupted in your home. You just know because the app tells you, your grid’s down and you’re on battery backup now. And now your battery is providing power to your home and it signals to the inverter to keep the solar system up and running. And now your solar system and battery together, in conjunction, are operating to power your home.
John: And if it’s during the day, then you’re charging that battery. And if it’s at night, then whatever charge that the battery has, you’re going to use that to power your home.
Brian: In theory, provided there’s sunlight, you can be a perpetually operating home off of the grid. So as long as there’s sunlight and you have battery capacity, because your solar is either powering your house and trickle charging or charging the battery, you’re able to stay operating in full, and we won’t say infinitely, but there are other weather criteria and things like that that disrupt you being an essentially perpetually operating home.
Typical Capacity of a Solar Battery
John: Right. I mean, what is the typical capacity of a solar battery? How long can I expect to run off of my battery system in my home if I do lose power?
Brian: It really depends on the battery system that you choose or that the installer that you’re working with offers. But I’d say, typically speaking, it’s around 10 kilowatt hours. And that’s for a small one, but you can add capacity, so it really depends on the platform. For us, we offer a couple different options. And it’s between…each battery is between 10 and 13.5 kilowatt-hours of power. And you can do multiples of those batteries, so it kind of depends on what your need is and what the loads are in your home and things like that. So a generator, there’s the kind of portable generators, whole home generators. And it’s kind of like, “Okay, you’ve got an essential load, so let’s keep the WiFi and the fridge operating.” Right? And maybe some lights if you had a portable generator. Or it’s a whole home and it can power everything.
So the batteries are more comparable to a generator in that respect, as a smaller battery system for…maybe we’re just targeting lesser loads. It kind of depends on the home and the lifestyle. Or another home might want everything backed up and have a larger capacity there.
Prioritizing Your Electricity Needs
John: So talk a little bit more about that. Can you actually prioritize your systems in your house and say, “Okay, if the power goes out and it switches over to the battery power, I only want it to power my refrigerator”? Maybe I have electric heat or something like that in the wintertime. I want that to stay on, but I don’t really care about my lights, or my TV, or something like that. Can you prioritize your appliances and equipment?
Brian: So, I’d say this is a yes and no type of question. Right? So typically speaking, a lot of installers and battery systems are designed for partial backup or kind of, what you said, prioritizing. So you’re doing that physically, you’re physically taking certain circuits and putting them on a backup panel. And that’s limiting, right? And it’s limiting, but it gives you maybe your essentials, so that’s kind of like an essential backup. Typically, what we do is, when we first started doing storage back in 2016 when this really started to become a thing, we realized right away that is not the way to go about it, but we should be looking at it as whole home and taking off the loads that can’t be supported by the battery. So we kind of had an inverse look at it, so we give all the power to the homeowner and said, “Okay, listen. You can back up your whole home, but don’t cook a turkey in the double oven if your battery’s not going to last very long.”
And if you have electric heat, it’s probably going to be limiting to be using that, so you want to use your secondary source if you have wood, or pellets, or oil, or gas fired boiler or furnace, let’s keep that on and let’s forego the electric heat. You probably don’t need your hot tub, or your pool pump, or your AC. So we kind of had more of a look like that, so instead of taking a select amount of loads that you can only use, we took a select amount of loads that you cannot use.
John: And like you said, that ends up giving that power back to the homeowner to say, “Okay, in this particular situation on this particular day, or this season of the year, or whatever it might be, these are the essential systems that I need,” and maybe I really do need my TV on because I need to be able to see what’s going on in the world or something like that. Or it’s not that cold, I can live without my heat right now, but I really am hungry and I need to cook some food on the stove, or something like that, so it gives that power back to the homeowner to decide what they feel like is the most important thing.
Brian: Absolutely, yeah. We want to educate them to make sure they understand that. You want to be an energy miser to elongate the life of the battery, but you have all the control. And what we also found is that the houses were wired in the ’20s and ’30s differently than they’re wired now. And so, some people might have…your heat might be hooked to a string of outlets and lights, or smoke detectors, or whatever the case may be. You have things, your WiFi’s on a random circuit over here because it’s plugged into that plug. So it was really challenging to neatly package an essential load situation for homeowners, where it was easier, frankly, to take the things you definitely can’t have or don’t want to have in an outage. You don’t need your electric dryer. I’m sorry. In an outage, you’re just not going to have it, but you’re going to have everything else.
So that way, they can have their communications of WiFi. They can have all their lights in their house. They can have all their outlets. But we just either take things out, to meet code is one thing, but also to be responsible to make sure that they’re getting a good experience for their backup storage, and then just educating them on, obviously, regardless of what type of heat you have, you want to keep it as low as you can tolerate when in an outage. You want to mitigate standing in front of the fridge and deciding what you’re going to eat with the fridge door open. You want to make sure they have something they can cook on, but maybe not everything. Right? Do you need a double oven and a microwave and an induction cooktop? Probably not. Let’s choose one and that’s going to be what we cook with, things like that.
John: And you shouldn’t have every light in your house on anyway. You don’t want to have that in any case, but maybe be a little bit more careful. Maybe you can go up to bed with a flashlight and not have to turn your lights on in your bedroom or something like that.
Brian: Absolutely. I mean, we’ve done some really, really complex storage systems that integrate multiple battery systems, not just the batteries, but the systems themselves, the transfer switches, and then multiple batteries on that. And they interact with a generator system and things like this. So we’ve done some really complex and interesting systems that, for the customer, it’s everything. A lot of times, these are large properties with significant load, and geothermal, and complex heating and cooling systems and things like that, that require more backup to be able to take care of that.
Lifespan and Maintenance on Solar Batteries
John: I know battery technology these days is a lot better than it used to be. But occasionally, even with my phone, say my cellphone, you might have to get the battery replaced after a few years or something like that. What’s the typical lifespan on a solar backup battery? Is there any maintenance that’s required throughout the years as well?
Brian: Good question. So again, with all the energy systems that we installed, we really strive to make it no maintenance. But all products do have some failure or some things that need maintenance on them at some point. We’d love it if none of them ever did. So batteries typically are mostly electronics, aside from the battery core themselves. They can need service. Typically speaking, they need to be replaced if there’s a problem. And generally speaking…because a lot of times they’re sealed units, so the manufacturers basically replace the whole thing because they have, I’d say, less failures than we may expect. And they want to see what went wrong and they want to pull the unit apart and diagnose it so they can mitigate and engineer that failure out for future products.
So the products themselves usually have a 10-year warranty. So it’s supposed to be operating at 70% of its original capacity for 10 years. So that means it’s going to last significantly longer than 10 years. I would say it’s really safe to expect batteries to be really effective and have good capacity for 20 plus years. But again, you pointed out the phone. Right? So we have a phone and we see the battery start to need charging more and the battery life start to decline. And maybe it doesn’t do as well in hot and cold. And so now we get a case that has a battery in it and we put that on our phone, and now we’ve doubled our battery life.
Similarly, you can do that with battery systems as opposed to replacing it, you can add battery capacity in the future. And that causes less stress on the initial battery and it will elongate the life of that battery as well. So we’ll say maybe you get a battery, and 10 years from now, you decide you want to add another battery. And that will help the life of the initial battery for a longer lifespan.
The Cost of a Solar Battery Backup System
John: How significant is the cost of a battery backup system for your solar panels? You’re getting solar installed on your house and you want to add battery backup to that. Does that add a significant amount of cost? And then maybe give me a little bit of a kind of cost/benefit analysis. Is that worth it for me to have that extra cost?
Brian: Yeah. I’d say when batteries first came out, and we still do, we want to compare them to a generator. Right? Why is the customer looking at a battery? So typically speaking, it’s because they fall into a few different buckets. Right? It’s, “I lose power lot and I’m in an area that it doesn’t get brought back up quickly, and so I’m going to get a generator, but I realize I’m getting solar, I might as well get a battery”. Right? Doesn’t that make sense? We’ve talked through that. And of course, a battery with a solar application becomes a solar electric power generator. Right? And so, it’s a smart piece.
And then as opposed to…cost wise, they’re similar, right? So getting a battery system would be similar to getting a whole home generator system. You’re going to be sized for what you need. And there’s infrastructure that needs to happen in order for that system to be installed. The difference is, with a battery, it qualifies for the 30% federal credit. And then, depending on what region you’re in and what utility you’re in, there are actually incentive programs for what we call a virtual power plant, or VPP, or demand response programs, that are going to incentivize you, through the utility, to have a battery system.
Demand Response Programs
So, in Massachusetts, for instance, National Grid and Eversource have a demand response program, and they will pay you for access to your battery during peak demand events. This is summertime on the hot and humid days where everyone’s got their pool and their AC going, as opposed to the utility having to buy additional power on the open market or fire up diesel auxiliary power plants to meet the demand, they’re going to leverage a fleet of battery systems that are installed in the region and locally be able to discharge power onto the grid from that battery unit for their homes and neighbors next door. And then they pay you. Right now, that’s a five-year program.
Vermont has a really strong program where the utility’s either giving away, or you’re able to lease, a battery at a very, very low cost to have that battery backup. That’s more because instead of the big infrastructure that the utility wants to put into the grid, they’d rather just localize that power and resiliency to that power through the storage system.
John: How do those contracts work? Do you have an agreement with them that you can take power during those peak times from my battery, but I want to retain at least 50% of my capacity of my battery at all times? Something like that?
Brian: Great point. Yeah, absolutely. So in Massachusetts for Eversource and National Grid, for instance, they can’t take more than 80%. So they can’t leave you with less than 20% capacity. There’s also…the battery systems have a storm feature, so one battery system we use has Storm Watch. The other one has a different name for it, Storm Control or something. It’s an option you turn on. It’s hooked into the National Weather Service or NOAA. And so, what happens is, if there’s a nor’easter, or a hurricane, or a major weather event coming, it overrides all the settings, makes sure your battery’s fully charged, and then the utility cannot take power from you if that setting has been engaged.
Similarly, you get a notice before the event. So, it’s typically between 2:00 PM and 7:00 PM in the summer months. And they anticipate about 70 events per season for that summer season. But you can opt out, so you’ll get an email or a notification on your app. And if you, for whatever reason, say “I don’t want to be in this event,” you can opt out of that event. And then therefore, the utility can’t take power from you. So there are some checks and balances, so to speak, so the customer ultimately has the choice. But you do want to opt into enough of these events to make it lucrative and so that you’re going to get significant payback on it, and it makes a lot of sense in that regard. And then Maine just opened up through Efficiency Maine, opened up their new demand response program for storage as well, so they have a similarly lucrative program as well for customers to receive income based on sharing their battery capacity with the grid.
John: So, then that can actually help to offset the cost of the battery itself.
Brian: It helps offset the cost of battery. It helps lower…ultimately, the idea is that it will lower the demand on the grid, and therefore, lowering the demand will lower the cost, so it will lower the stress on the grid. It will lower the market demand so that our region is not needing to buy as much power on the open market and bring that into our region. So, it has multiple layers of benefit, but for the individual homeowner that’s investing in a battery, you absolutely … You get a “payback”, right? It used to be none. It used to be just an additional cost. But now, okay, it does…It’s very clear that the IRS has come out with language that it does qualify in full for the tax credit. And there’s these additional utility programs that you can opt into depending on your location to get a further offset of your investment.
John: All right, well, that’s really great information, Brian. Thanks again for speaking with me today.
Brian: Awesome, John. Thanks for having me.
John: And for more information, you can visit the website at solarisrenewables.com, or call 781-270-6555.