Solar panels do i need a battery in case of outage

[Jobseeker2013]

Our house is in suburban Chicago with very infrequent outages of any kind in the 10 years we have lived there. I think the longest has been a few hours. But things do happen so I assume a battery is needed? The solar panels net credits incentives will be 3k and battery net will be 7k with a week of power. So my pay back period is 11 years with the battery but less than 4 years without. The battery will partially power the house. I believe i choose 5 critical items to power. They offer a tesla power wall. A full house requires 2 or 3 total batteries.

I think for peace of mind a battery is needed?

[exodusNH]

Our house is in suburban Chicago with very infrequent outages of any kind in the 10 years we have lived there. I think the longest has been a few hours. But things do happen so I assume a battery is needed? The solar panels net credits incentives will be 3k and battery net will be 7k with a week of power. So my pay back period is 11 years with the battery but less than 4 years without. The battery will partially power the house. I believe i choose 5 critical items to power. They offer a tesla power wall. A full house requires 2 or 3 total batteries.

I think for peace of mind a battery is needed?

It's probably not worth it. It'll be cheaper to get a gasoline generator for those few occasions if you truly can't live without power.

You could also look at a control system that offers "islanding." That will obviously only produce power during the day, but it might be a cheaper option.

[simplesimon]

Our house is in suburban Chicago with very infrequent outages of any kind in the 10 years we have lived there. I think the longest has been a few hours. But things do happen so I assume a battery is needed? The solar panels net credits incentives will be 3k and battery net will be 7k with a week of power. So my pay back period is 11 years with the battery but less than 4 years without. The battery will partially power the house. I believe i choose 5 critical items to power. They offer a tesla power wall. A full house requires 2 or 3 total batteries.

I think for peace of mind a battery is needed?

I had a similar decision to make when I had solar installed. The battery provides almost no benefit when there is no power outage. In MA where I live the utility can draw on the battery and will pay you when they do so, so there is a little bit of benefit there. I calculated no breakeven for me despite that incentive, but even 11 years payback period would be too long for me. I think battery technology is not as far along the curve as solar panels are so I didn't think it was worth it.

[quantAndHold]

We got solar 16 years ago, and they didn’t even offer batteries then.

Yes, your grid tied solar system won’t work in an outage, unless you have a battery and a transfer switch.

I’ve thought about getting batteries, but like you, outages are infrequent where I live. What I decided to do is have a generator input installed in my garage. The battery in my electric car has plenty of power to power the fridge and a few lights for several days.

[TomatoTomahto]

Yes, your grid tied solar system won’t work in an outage, unless you have a battery and a transfer switch.

That’s true for many (most?) solar systems, but at least Enphase has panels with microinverters that can “island” the system for safety. I believe it’s their IQ8 series, but I could be wrong.

Most batteries tied to solar have internal “transfer switches.”

Finally, while I’m not someone who calculates “break even” (if I did that, I’d never have had kids), I get paid around $5k annually by my utility to allow them to draw down my battery in the summer peak hours.

[Marq1]

Bought my gas generator 16 years ago and have used it about 4 times. Power goes out but 99% of the time it's off for short duration that you don't even need to worry. Of course we're in mid MI so about the worst we have to worry about is summer storms and ice! Both are pretty rare up here!

[PNWHiker]

The battery will partially power the house. I believe i choose 5 critical items to power. They offer a tesla power wall. A full house requires 2 or 3 total batteries.

Your installer is badly misinformed. If they are offering a Powerwall 3, you absolutely don't need 2 or 3 to power the whole house. One PW3 will provide enough output to power all of your non-heavy loads. More PWs get you longer backup duration, and more power to run heavy loads, but one PW3 can cover emergency needs for sure.

We have a 9.9kW solar array and a single Powerwall 3, and we have whole-house backup, no sub-panel or critical loads panel required. Our HVAC is on load-shedding relays in case the grid goes down overnight or while we're away form the house, but absolutely everything else is powered by the Powerwall.

I suggest three things:
- In locations without VPP (where the utility can tap into your battery storage and pay you for it) or Time of Use cost differentials, the battery is essentially an insurance policy against grid outages, nothing more. You need to decide whether the extra cost of the battery is an insurance premium you're willing to pay. You will not get payback on the battery cost.
- If you only have one installer quote, get at least one more. Check Energy Sage to see other installers in your area.
- Do some research and decide what is important to you before getting any more quotes or deciding what to get. Installers will try and sell you on lots of things to pad their invoice (as in the battery offer above). Make a plan for what you really want and stick to it.

Hope this helps!

[enad]

check with your utility and find out what you can/can't do. Some places will not use your battery even when power is out, some places will not let you use your battery when power is out, some places will not let your solar array charge your battery when power is out.

[Jobseeker2013]

So the battery back up on solar will give me power when electric customer power is out? So if i were still an electric customer, I would not have power anyway. So if i do not have a battery, i simply be out of power for the exact duration an electric customer is? Is this an accurate statement?


I think for some reason i tbought with solar i would have more power outrages than an electric customer. Well that doesnt make sense.

[TravelforFun]

The battery in my electric car has plenty of power to power the fridge and a few lights for several days.

How do you do that?

TravelforFun

[simplesimon]

So the battery back up on solar will give me power when electric customer power is out? So if i were still an electric customer, I would not have power anyway. So if i do not have a battery, i simply be out of power for the exact duration an electric customer is? Is this an accurate statement?


I think for some reason i tbought with solar i would have more power outrages than an electric customer. Well that doesnt make sense.

You'll still be on the grid. Your frequency of outage is the same as if you were an electric customer. Outages aren't more frequent due to have solar panels. If someone told you that, they are wrong.

But if you had a battery, you would not experience an outage.

If you feel like the infrequent outages was not that big of a deal in the last 10 years, then you probably don't need a battery. It would then be a luxury to have power available at all times without interruption.

[mchampse]

So the battery back up on solar will give me power when electric customer power is out? So if i were still an electric customer, I would not have power anyway. So if i do not have a battery, i simply be out of power for the exact duration an electric customer is? Is this an accurate statement?


I think for some reason i tbought with solar i would have more power outrages than an electric customer. Well that doesnt make sense.

I assume you may be planning or already have a heat pump HVAC and/or HPWH. With gas, you never have to worry about an outage. A battery may make sense from that perspective but as you mentioned power outages are pretty rare.

[exodusNH]

So the battery back up on solar will give me power when electric customer power is out? So if i were still an electric customer, I would not have power anyway. So if i do not have a battery, i simply be out of power for the exact duration an electric customer is? Is this an accurate statement?


I think for some reason i tbought with solar i would have more power outrages than an electric customer. Well that doesnt make sense.

I assume you may be planning or already have a heat pump HVAC and/or HPWH. With gas, you never have to worry about an outage. A battery may make sense from that perspective but as you mentioned power outages are pretty rare.

That's only true with systems that have no electronics involved in maintaining a flame. E.g., and old-school, passively vented water heater with a standing pilot.

[exodusNH]

So the battery back up on solar will give me power when electric customer power is out? So if i were still an electric customer, I would not have power anyway. So if i do not have a battery, i simply be out of power for the exact duration an electric customer is? Is this an accurate statement?


I think for some reason i tbought with solar i would have more power outrages than an electric customer. Well that doesnt make sense.

Unless you get a system that can island or you have a battery, when the grid goes down, you lose power.

You won't lose power otherwise. Sometimes you'll be pulling from the grid. Sometimes you'll be supplying the grid.

[mchampse]

I assume you may be planning or already have a heat pump HVAC and/or HPWH. With gas, you never have to worry about an outage. A battery may make sense from that perspective but as you mentioned power outages are pretty rare.

That's only true with systems that have no electronics involved in maintaining a flame. E.g., and old-school, passively vented water heater with a standing pilot.

Have never had a gas water heater that needed to be plugged in but YMMV. Forced air gas HVAC won’t work without power, but wall heaters will.

[TomatoTomahto]

check with your utility and find out what you can/can't do. Some places will not use your battery even when power is out, some places will not let you use your battery when power is out, some places will not let your solar array charge your battery when power is out.

Can you please name one utility that does that? I don’t know of any.

[Valuethinker]

Our house is in suburban Chicago with very infrequent outages of any kind in the 10 years we have lived there. I think the longest has been a few hours. But things do happen so I assume a battery is needed? The solar panels net credits incentives will be 3k and battery net will be 7k with a week of power. So my pay back period is 11 years with the battery but less than 4 years without. The battery will partially power the house. I believe i choose 5 critical items to power. They offer a tesla power wall. A full house requires 2 or 3 total batteries.

I think for peace of mind a battery is needed?

I really don't think you need a battery NOW. You say that outages are infrequent.

They will be cheaper, and denser, in the future.

What I don't know is if you can get the system configured for a future battery -- so an isolation switch plus anything else necessary? I think someday we will all have them. Electricity during sunny daylight periods will be virtually free (at least in summer, at the wholesale level). Then it will ramp very very steeply from about an hour before sundown. So the value of your solar PV system will really be in not importing energy in that 4pm-10pm time slot, say.

But a battery now? Unless there are compelling economics? You are Commonwealth Edison customer? They have a big nuclear estate, from memory. Nuclear energy runs all the time, so they don't have big needs (that batteries can fulfil) outside of the depths of winter and during heat waves in summer. (I am guessing here, from vague memories re Com Ed).

[Valuethinker]

check with your utility and find out what you can/can't do. Some places will not use your battery even when power is out, some places will not let you use your battery when power is out, some places will not let your solar array charge your battery when power is out.

Can you please name one utility that does that? I don’t know of any.

It sounds rather like California - but I am not sure.

[vriguy1]

Can you even have such a battery installed? Some years ago I was told that Illinois does not allow household battery backup. I live in the Chicago suburbs and I was wondering then about the Tesla wall. I ended up getting a Generac gas generator for back up.

[TomatoTomahto]

Can you even have such a battery installed? Some years ago I was told that Illinois does not allow household battery backup. I live in the Chicago suburbs and I was wondering then about the Tesla wall. I ended up getting a Generac gas generator for back up.

Not only is it legal, Illinois will give you a rebate of $300 per kWh of battery.

[TomatoTomahto]

Can you please name one utility that does that? I don’t know of any.

It sounds rather like California - but I am not sure.

It would surprise me. California has a surplus of daylight solar power and needs desperately to encourage storage to power non-sunlight hours.

[mchampse]

Can you please name one utility that does that? I don’t know of any.

It sounds rather like California - but I am not sure.

In California you can do all those things.

[neowiser]

Here in Southern California many people are facing multiple days-long power outages. The utility (Southern California Edison) aggressively cuts power to overhead supply lines during wind storms. People with solar and battery backup are getting their money’s worth, but appliances requiring 240V outlets (washer/dryer) don’t work. Based on local social media chatter, the best generator is the Firman 7500W Running / 9400W Peak Tri Fuel Generator available at Costco for $1000 (sold out in most of CA). Fuel is likely to be difficult to acquire in a significant disaster, leaving solar+ battery as the best survivalist option.

[exodusNH]

That's only true with systems that have no electronics involved in maintaining a flame. E.g., and old-school, passively vented water heater with a standing pilot.

Have never had a gas water heater that needed to be plugged in but YMMV. Forced air gas HVAC won’t work without power, but wall heaters will.

Again, only with standing pilots. There have been efficiency pushes to eliminate standing pilots in favor of electronically fire ones.

Depending on local code, passively vented water heaters are no longer allowed. I'm grandfathered in with a water heater venting into the basement chimney. But a substantial remodel would require it to be replaced with active venting.

Don't get me wrong -- I love gas-fired appliances. It's just that the days of guaranteed functionality without electricity are limited.

[jharkin]

Our house is in suburban Chicago with very infrequent outages of any kind in the 10 years we have lived there. I think the longest has been a few hours. But things do happen so I assume a battery is needed? The solar panels net credits incentives will be 3k and battery net will be 7k with a week of power. So my pay back period is 11 years with the battery but less than 4 years without. The battery will partially power the house. I believe i choose 5 critical items to power. They offer a tesla power wall. A full house requires 2 or 3 total batteries.

I think for peace of mind a battery is needed?

It's probably not worth it. It'll be cheaper to get a gasoline generator for those few occasions if you truly can't live without power.

+1 When I put in solar I ran the numbers over and over and there was no way I could make the battery pay back before it reached its warranty/replacement age (10 years for the chemistries I was quoted).

The real benefit to a battery is when you get either:
- Time of use billing where there is an advantage to charge the battery during day when rates are low and use it at night when rates are high
OR
- Have utility incentives to let them draw it down/feed the grid during peak load periods


I don't think the battery for power outage backup is compelling because:
1 - The capacity needed for any long outage is HUGE (you may need 10-20kWh/day even if you DONT have electric heat or cooling)
2- The times you tend to loose power and need the backup are the exact times that solar doesn't work to charge if (bad weather)

[Toddo]

I don't think the battery for power outage backup is compelling because:
1 - The capacity needed for any long outage is HUGE (you may need 10-20kWh/day even if you DONT have electric heat or cooling)

Solar isn't very practical for use for a number of reasons, primarily because we don't have a place to put them because of so many tall trees. But I did look at batteries for a different reason. We were without power for 12 days because of Hurricane Helene, and our two-year-old whole house generator failed after six days. From what I'm learning now small air-cooled generators simply are not capable for running continuously for days on end, despite the fact that their manufacturers don't admit that.

We don't have electric heat or cooling, so our total load is fairly small. We need power only for refrigeration; the well pump; the electronics, fans, and pumps for the hot water/heating system; and a few lights. I explored the idea of getting a battery system that would power the house for half a day or so, and using the generator intermittently to recharge it. Turns out it would be much cheaper to get a backup generator for our backup generator.

[Sagefemme]

We got rooftop solar in May 2024. Battery prices and capacities seem to be improving all the time, so we made sure our system is easily expanded to include batteries, but we won't get them until prices are better, or the world changes in some way that makes energy storage essential. We don't have an electric vehicle but I imagine we will at some point and my understanding is that the fully charged vehicle might be able to provide some power to the house?

[TomatoTomahto]

We don't have an electric vehicle but I imagine we will at some point and my understanding is that the fully charged vehicle might be able to provide some power to the house?

You probably won’t find many bigger fans of EVs, solar, and batteries than me here on BH, and it’s all very promising, but I am skeptical. I paid dearly for 52 kWh of residential battery and would love to have my 100 kWh vehicle (soon to be followed by my wife’s EV) take the place of residential battery, but in a complicated house, I don’t see it.

There will be a way to power simple appliances from an EV, and some are supposed to be available now, but I haven’t seen one in use for a complex house. Trust me, I want to be proved wrong.

[Sagefemme]

We don't have an electric vehicle but I imagine we will at some point and my understanding is that the fully charged vehicle might be able to provide some power to the house?

You probably won’t find many bigger fans of EVs, solar, and batteries than me here on BH, and it’s all very promising, but I am skeptical. I paid dearly for 52 kWh of residential battery and would love to have my 100 kWh vehicle (soon to be followed by my wife’s EV) take the place of residential battery, but in a complicated house, I don’t see it.

There will be a way to power simple appliances from an EV, and some are supposed to be available now, but I haven’t seen one in use for a complex house. Trust me, I want to be proved wrong.

I believe you, and for now I am content with my small-ish array on my roof and no storage capacity. It does seem like a rapidly shifting space, though, so we will see what the future holds!

[Bigbmn]

Saw this post and felt compelled to reply as a real world example. We installed Solar with a a single power wall, and this has worked great for us. I work at home, and the few times we've had a grid outage, let's say 1/2 dozen times over the year, they only lasted for a few hours at the most, and we can just continue carrying on as normal. Also the battery is used every night, charged from the solar during the day so you are in effect using the power from the sun, during the evenings. Any excess over this is sold back to the grid. Of course, if there was an extended outage, we would run out of energy, but there has only been one storm in the 26 years that we lived here that lasted for a week.

[Bigbmn]

Saw this post and felt compelled to reply as a real world example. We installed Solar with a a single power wall, and this has worked great for us. I work at home, and the few times we've had a grid outage, let's say 1/2 dozen times over the year, they only lasted for a few hours at the most, and we can just continue carrying on as normal. Also the battery is used every night, charged from the solar during the day so you are in effect using the power from the sun, during the evenings. Any excess over this is sold back to the grid. Of course, if there was an extended outage, we would run out of energy, but there has only been one storm in the 26 years that we lived here that lasted for a week.

[retired early&luv it]

I do not have solar, but if I did, I would not get the battery. My sister has solar, has no battery.

If I was in a rural area where power outages are frequent and may last for days, I would consider either battery or generator backup. I have never in my 71 years of living in urban areas had a power outage that lasted more than a half day. Yes it could happen, but not worried about it.

I have a small battery backup for my modem, router, and the little black box that plugs my landline phone (VOIP) into my router. That should run a few hours at most, but I have never found out if it works, have not had an outage since I bought it. And even if there was a power outage, I have no idea if the other end of my fiber optic line would have the power needed to connect me to the rest of world.

Someone in this thread commented on hot water. My gas hot water is from a tankless unit, that needs electric power to operate, there is an electric blower to blow air through the combustion chamber. The older gas tank type water heaters often did not have a blower so no power was needed.