Solar Power during a Power Outage without Batteries

[Solarguy3500]

Ephase is releasing their new IQ8 line of microinverters soon. This is exciting because the IQ8 line is capable of forming a microgrid without batteries.

Enphase launches microgrid-forming microinverter line

The IQ8 solar microinverters are capable of forming a microgrid during a power outage using only sunlight, providing backup power without a battery. The systems also allow any size Enphase battery to be paired with a solar system.

pv-magazine-usa.com

While this has been done before by SMA, that solution was very limited and only gave you one outlet capable of 2000W Max when the sun was shining. The IQ8 micros will still have the limitation of only giving you power when the sun is out if you don't get batteries, but you'd be able to utilize the full potential of your solar panels and not be limited to just one outlet.

You can also add batteries for storage if you want, and I think that one nice feature of these micros is that they will allow you to buy a smaller battery backup system that is sized just to get you through the overnight hours and cloudy periods.

 

[semipro]

I think this is a game-changer. Many of those wishing to use solar PV back off when they find out they can't tap the power when the grid is down without investing a lot in batteries. I think this may really expand the PV market.
This should really be interesting to those that have sources of heat that don't require electrical power (wood, gas).

 

[peakbagger]

It is quite a step forward if they start shipping, they have been promising it for a while. The hassle is dealing with shadows and clouds plus surge loads. At some point the amount of solar coming into the array is less than the connected load, at that point, its a choice, Shut off the AC power or let the voltage drop which drives the current up to the point where components fry. If the system shuts the inverter off, then when it turns back on there can be a start up surge. So how does the system know how much power it needs to be able to generate when an unknown load is hooked up? The system will only be capable of the power coming in via the panels so it may not be able to supply the load. With a generator there is some rotational mass which helps a bit and a governor that will add gas to the carb but the Enphase does not have either. My guess without storage they will limit the rated output significantly like the SMA secure power system did.

Having a high surge low output battery or ultra capacitor in the loop will really help things, that is what Toyota has used on fuel cell cars in the past, the fuel cell supplies average power and keeps the capacitor charged until its needed. It then discharges for a surge demand.

As I reported a couple of weeks ago my older enphases synched to my Sunny Island quite well but I have a couple of large batteries in the background.

 

[EbS-P]

I have been contemplating an off grid install, 2-3, kw to charge an EV, run a mini split and have emergency power for a refrigerator. My work schedule has me home a lot. I don’t see the extra cost of a battery as ever breaking even. We don’t have good sun for a larger system due to trees. Don’t see the point in cutting them down. Whole point would be to reduce carbon footprint. Not too concerned with money savings. Would not want to finance the install. I haven’t looked into it that much but my 15-20 minutes didn’t reveal any great solutions.

Evan

 

[peakbagger]

I have been contemplating an off grid install, 2-3, kw to charge an EV, run a mini split and have emergency power for a refrigerator. My work schedule has me home a lot. I don’t see the extra cost of a battery as ever breaking even. We don’t have good sun for a larger system due to trees. Don’t see the point in cutting them down. Whole point would be to reduce carbon footprint. Not too concerned with money savings. Would not want to finance the install. I haven’t looked into it that much but my 15-20 minutes didn’t reveal any great solutions.

Evan

Its pretty simple these days, installers have aps on their phones that they take to the site and take a photo. From there they can estimate the shadows and figure out where to put the panels. If you have shadows microinverters are the way to go. My guess is the proposed system in the OP is going to be more than microinverters, its going to be central brain required to coordinate the operation. 2 to 3 KW is kind of tight for an EV. My Rav4 42 miles of EV eats up a days worth of power from my solar trailer which is around 2.3 KW

 

[Solarguy3500]

My guess is the proposed system in the OP is going to be more than microinverters, its going to be central brain required to coordinate the operation.

Correct.

In order for the IQ8s to do backup power, with or without batteries, you'll need to get the Enphase Smart Switch, or whatever they are calling it these days. It's basically a transfer switch and the Enphase equivalent of the Tesla gateway for Powerwalls.

Without the switch, the IQ8s will only be capable of grid tied operation like the current model IQ7s.

 

[semipro]

At some point the amount of solar coming into the array is less than the connected load, at that point, its a choice, Shut off the AC power or let the voltage drop which drives the current up to the point where components fry. If the system shuts the inverter off, then when it turns back on there can be a start up surge. So how does the system know how much power it needs to be able to generate when an unknown load is hooked up?

Good point.
Perhaps smart load centers may one day address these issues - something that energizes circuits based on available power and predetermined priorities.
A smart load center would also benefit systems with some battery/generator backup but not enough to power all loads simultaneously (like mine). I and others in similar situations have to manually energize/de-energize larger loads strategically when on backup power.

 

[peakbagger]

On the big commercial CHPs we always look at load management systems to do that load planning but we have big generators that we can rely on. Solar without a battery has zero reliability so I am unsure how it would be done. IMHO, this gets their proprietary equipment in the door and then when utility incentives like in Mass appear, the system is ready for a battery paid for by the utility who retains the right to dispatch it.

 

[begreen]

I could see installing this with a buffer battery for overnight loads, but not in our neck of the woods unless panels greatly increase their ability to produce power during extended cloudy periods like we see in the winter.

 

[EbS-P]

I think the whole battery storage is a luxury that if you have the extra money to spend it’s a great upgrade but the cost of the battery is a significant portion of the the overall cost. I was reading somewhere that some company is making a system that can use a generator or a APU- UPS backup as the reference signal to the inverter and allows you to set the percent power you want the generator to supply.

It’s a neat concept for when the grid goes down. I still want a car charging system that allows backup AC when the grid goes down. But a gas generator is cheap and easy.

 

[semipro]

I think the whole battery storage is a luxury that if you have the extra money to spend it’s a great upgrade but the cost of the battery is a significant portion of the the overall cost. I was reading somewhere that some company is making a system that can use a generator or a APU- UPS backup as the reference signal to the inverter and allows you to set the percent power you want the generator to supply.

It’s a neat concept for when the grid goes down. I still want a car charging system that allows backup AC when the grid goes down. But a gas generator is cheap and easy.

This is intriguing.

I Powered My House with the Ford F-150 Hybrid

If the power goes out, can you use your truck to power your house? We decided to find out.

www.caranddriver.com

 

[EbS-P]

This is intriguing.

I Powered My House with the Ford F-150 Hybrid

If the power goes out, can you use your truck to power your house? We decided to find out.

www.caranddriver.com

Yep I really think this is the future of a smart grid. You set a minimum charge for your next 48 hours manual or AI setting. Utility company will give you credit for allowing them to control when they use power from your battery. Thinking 25% of an 80kwh battery could supply my house for probably a day or more if I was to conserve in any way. Really we just need peaking power. Power your 1/2 your house on your EV battery for the the 4 peak hours a day.

 

[SteveKG]

begreen said, "I could see installing this with a buffer battery for overnight loads, but not in our neck of the woods unless panels greatly increase their ability to produce power during extended cloudy periods like we see in the winter."

Yes, this cloudiness is a problem. We have a battery-based PV system running our home since 1985. The only way, at present, to get around the cloudiness thing is to have more panels than needed for powering the house and batteries during sunny times. Meaning a larger PV array. Yes, you don't get to use the excess electricity on sunny days, just the way it goes I have added panels numerous times over the decades as panels become much cheaper to purchase and our elec. needs grew past what we originally planned. We now can get by ok even on the cloudiest spells. And fortunately, a single panel today will cost far less than a panel in 1985 and put out ten times more electricity. Or something like that.

 

[Solarguy3500]

I could see installing this with a buffer battery for overnight loads, but not in our neck of the woods unless panels greatly increase their ability to produce power during extended cloudy periods like we see in the winter.

Yes, I was thinking along those lines too. The solar providing power on sunny days in an outage situation seems like it could effectively allow you to get a much smaller battery to get you through the nights and cloudy periods. Maybe even something like this which is less expensive than something like a Powerwall, and has the added benefit of being portable so you can take it on camping trips in an RV, etc.

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[Solarguy3500]

Yep I really think this is the future of a smart grid. You set a minimum charge for your next 48 hours manual or AI setting. Utility company will give you credit for allowing them to control when they use power from your battery. Thinking 25% of an 80kwh battery could supply my house for probably a day or more if I was to conserve in any way. Really we just need peaking power. Power your 1/2 your house on your EV battery for the the 4 peak hours a day.

View attachment 287480

Yes, I agree. It's really exciting to see what's on the horizon and hopefully will be widely available in the next few years.

Going even a step further than the hybrid F150, the all electric F150 Lightning will almost render home backup batteries like the Tesla Powerwall obsolete. If you get the transfer switch with the truck, you can have backup power capable of putting out 9.6 kW of power during an outage.
(broken link removed)

The other reason this is really potentially a game changer here in MA, is that over this past summer, the state issued a guidance memo to all the municipal inspectors that requires batteries installed in a home to have a closet built around them using 5/8 type X gypsum board and many inspectors are also requiring a fire rated door. This is to help contain a lithium fire if a battery were to ignite, and also to try to keep a fire started elsewhere in the house from reaching the batteries. Makes sense from a safety perspective, but adds to the installation cost and space needed for battery systems. Enter the F150. Since it's parked out in the driveway, none of those requirements apply.

Obviously, it doesn't make economic sense to buy the truck for the battery backup alone, but if you're in the market for a new vehicle anyway in the next few years when they actually start producing them in any kind of numbers, it's definitely worth thinking about

 

[begreen]

begreen said, "I could see installing this with a buffer battery for overnight loads, but not in our neck of the woods unless panels greatly increase their ability to produce power during extended cloudy periods like we see in the winter."

Yes, this cloudiness is a problem. We have a battery-based PV system running our home since 1985. The only way, at present, to get around the cloudiness thing is to have more panels than needed for powering the house and batteries during sunny times. Meaning a larger PV array. Yes, you don't get to use the excess electricity on sunny days, just the way it goes I have added panels numerous times over the decades as panels become much cheaper to purchase and our elec. needs grew past what we originally planned. We now can get by ok even on the cloudiest spells. And fortunately, a single panel today will cost far less than a panel in 1985 and put out ten times more electricity. Or something like that.

Unfortunately in northern latitudes one needs a boatload of panels to generate anything meaningful in winter, especially in a maritime climate. And you need a site that has good, southern, low-sun-angle exposure. That cuts out a lot of properties, including ours. By February things start improving rapidly, but Nov-Jan is not good here. At 1pm today we are producing 4-500w with ~6Kw worth of panels. On a sunny Dec. day we might get 3kw, but the low arc of the sun brings on lots of shading issues so only about 2 hrs worth.

 

[peakbagger]

Thus the need for long term storage and the only option is electrochemical, where some stable chemical is converted to another stable chemical reversibly. There are couple of chemistries that may meet that requirement but the intermediate equipment does not scale well.

BTW Mass fire departments are getting the willies about storage batteries. The codes and standards tend to lag new tech deployment. The only firefighting option of put a lot of water on the battery and let it run for 96 hours and then someone else needs to be deal with the toxic soup that is left over. On my latest battery project, we have to have a hefty buffer on all four sides of the battery. I have heard some debate that the next step is a permanently installed deluge system tied to a fire main. My guess is at some point the insurance companies will get involved and there will be surcharge for a Lithium Home battery. There are other chemistries out there but they generally have lower density. There are a couple of battery enthusiasts on You Tube with videos of post battery fire damage. I dont think anyone would voluntarily want one in their living space and I personally wouldnt trust one in my garage. Then again, I have battery hybrid in the garage

 

[woodgeek]

I'm a broken record on this issue, but anyone with any plug-in hybrid or pure EV can hook up a 2 kW sine wave inverter to the 12V side, and get as much power as a small genny for maybe $300 in parts. In a system that is a lot quieter and lower maintenance and much lower gas usage per kWh than a genny. There are a couple million vehicles in the US today that this would work with, and I've been doing this since 2016 with 3 different EVs without issue (LEAF, Bolt, Volt Gen 1).

Bottom line is that all EVs have a 1500W output DC-DC converter for running all the 12V utilities. With a decent (90% eff) sine wave inverter, you can do 1350W continuous AC, with a 2kW few minute surge capacity due to buffering by the onboard 12V battery.

You could run that indoors on extension cords like the F-150 dude, or my preference, make a 240V cheater cord that ties the two hots together, and backfeed 120V with that. Then all your 120V loads run, and all the 240V loads see no voltage. (I flip the 240V breakers anyway just t be safe). And voila...the whole house runs except the 240V appliances. And I have to be careful to unplug some of the higher power kitchen countertop stuff. No bigs if you have a gas range.

My recent inverter upgrade actually has a bluetooth link to a phone app, so I can see all the power specs in real time while sitting in my living room.