New tech can make your house a solar microgrid
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Scary Devil Monastery
Ars Scholae Palatinae
I'm not sure most people will grok what a leap forward this is. Up to 50% cheaper than the existing default setup of bundled panel feeding into inverter/battery and then the grid just by a different engineering approach?
If this scales...
Question is whether this is the only company building something like this. I hope not.
If this scales...
Question is whether this is the only company building something like this. I hope not.
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Can someone expand upon this? Why can't I just put in a large switch to change from on-grid mode to off-grid mode, like the switch described in the article, and stick with a single large inverter? In my ignorance, it sounds like this company is selling the distributed microinverter model by claiming its on-grid/off-grid ability is unique to its system.
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Unfortunately the only way to safely power your home when the grid is out is to physically disconnect it, that's so you don't backfeed power and shock the maintenance guys working on the lines they think are turned off.
I'm guessing that what the load controller and other hardware does, and most likely the smart microinverters won't push any power in "off-grid" mode until they get a signal or can verify that the grid really is disconnected.
Kind of surprised they couldn't get the price any lower but maybe there is more hardware than just an anti-islanding relay...
I'm guessing that what the load controller and other hardware does, and most likely the smart microinverters won't push any power in "off-grid" mode until they get a signal or can verify that the grid really is disconnected.
Kind of surprised they couldn't get the price any lower but maybe there is more hardware than just an anti-islanding relay...
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I'm going to skip past a product like this or a home battery and go straight to an electric vehicle which supports bidirectional charging. Power outages in my area have fortunately never been more than about 12 hours, so a normal EV battery which has enough power to cover my home for at least 2-3 days would more than cover those needs. That is, assuming I'm not misunderstanding the ability to use the EV battery power even when the grid is down.
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So how do the battery-backed systems work as a large UPS effectively?
Or do they have more smarts that prevents them feeding power to the grid if they don't sense any grid power?
If that's the case, why can't regular inverters do the same without a battery? Is it just inverter manufacturers cheaping out?
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I looked at a solar install in my area but was dissuaded by all the proprietary stuff and the fragmentation. The monitoring systems, relays, panels, etc. change by vendor, and have to be maintained by the vendor when something goes wrong.
I wish this was something the electricity company offered, or the government paid them to offer through subsidies. The costs are also pretty high and we're poor at the moment thanks to childcare.
I wish this was something the electricity company offered, or the government paid them to offer through subsidies. The costs are also pretty high and we're poor at the moment thanks to childcare.
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I submitted a request for quotes through Energy Sage less than a year ago to install solar and the total cost was about $70k. I got the impression that the (only) installer that responded with a quote didn't want to travel to my location. Which is sad because it seems like more rural locations are those that might benefit the most from solar generation and backup since outages in those areas can run much longer than more localized (and higher priority) urban outages.
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the underlying problem that the article didn’t really touch on us that most solar installations are grid-tied. Which means they need the grid to function. Why? If there is an outage during the day, and the transformer on your street breaks or a power line gets cut, the people repairing it need to know that the load side (the houses and businesses) aren’t back feeding power into the grid via solar or some other backup generator. Any sort of home backup power system needs a smart disconnect between the grid and your house to prevent you from back feeding energy onto the grid.
Whether you have a single large inverter or a bunch of micro inverters, it doesn’t matter from a practical standpoint.
The only innovation that I can figure out here is that each microinverter would need to sync up with all the other microinverters so that together they produce a 60Hz AC signal in sync. If the numerous microinverters were not in sync the AC output of the solar array would be unusable.
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This is the exact system I'm having installed in November this year.
21.16kW with 30kWh battery backup. Running me about 98k, installed, before incentives.
21.16kW with 30kWh battery backup. Running me about 98k, installed, before incentives.
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The key to avoiding homicide charges is to ensure that your home is disconnected from the grid when you are dumping power into it, whether from an EV battery, wall battery, solar setup, or whole house gas generator. You really really really need to have whatever you do installed by a licensed and experienced electrician and fully inspected by qualified inspectors.
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I literally passed inspection of my install Monday for this exact system (with the battery). I'm waiting for the power company to come switch the meter so I can start using it.
The hardware does have an auto disconnect when the grid goes down and powers a good chunk of my house in that mode. And yes, it's effectively a large UPS. Except it can charge during the day if power's out.
There's also a manual disconnect outside for firefighters so that if they come to the house and it's on fire, when they pull the meter they can also disconnect the solar at the same time.
The app is pretty cool - one thing they did do is that you can connect directly to the system over your home wifi/network (there's an ethernet port on it, but the app is only Android and iphone) which will let you choose the amount of power to use overnight as a time shift, or keep in case of an outage. The online component does have some use as it'll watch for storms and automatically change your battery use to keep a larger charge when there's a bad storm coming.
My battery is a 10 kWh battery, but I can add more in 3.33 kWh chunks if I need to. I also overbuilt my need, so I'm hoping that I'll be getting checks from the power company and will be making my power company's mix a little bit greener.
Can't wait until I start producing!
The hardware does have an auto disconnect when the grid goes down and powers a good chunk of my house in that mode. And yes, it's effectively a large UPS. Except it can charge during the day if power's out.
There's also a manual disconnect outside for firefighters so that if they come to the house and it's on fire, when they pull the meter they can also disconnect the solar at the same time.
The app is pretty cool - one thing they did do is that you can connect directly to the system over your home wifi/network (there's an ethernet port on it, but the app is only Android and iphone) which will let you choose the amount of power to use overnight as a time shift, or keep in case of an outage. The online component does have some use as it'll watch for storms and automatically change your battery use to keep a larger charge when there's a bad storm coming.
My battery is a 10 kWh battery, but I can add more in 3.33 kWh chunks if I need to. I also overbuilt my need, so I'm hoping that I'll be getting checks from the power company and will be making my power company's mix a little bit greener.
Can't wait until I start producing!
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Yes, basically is that what they are delivering here. If have the feeling there are too many components in this setup.
however off-grid without (a small) battery is rather complex.
-It needs to disconnect from the grid to prevent backfeeding into the grid and electrocuting the engineers. Normally the inverter detects Grid going down/undervoltage/overvoltage and goes in error. Now it needs a phyical switch to disconnect.
-It needs to generate its own frequency. easy.
-It needs to run in a mode where the usage is matched to the generation. Normal mode is to convert all PV power, but since there is no buffer, the house will always use less than 100% that is generated. I suppose this is the "SMART"part.
If you buy this, i think you need to be very aware if you buy extra components that give you some uptime that can fail if a big cloud goes over your house.
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That's a crazy amount. I just used Energy Sage and paid $12k. My system isn't very big though. How many panels were you trying to install? Did you want batteries?
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Why would the grid switching be any different from that for a back-up generator. Our generator can output 18 kW and switches in and out automatically with the grid on and off. And after a storm, the noise tells us that half our neighbors also have back-up generators. This is a solved problem, and IIRC correctly the isolator switch was about $2K including installation into the house electric supply.
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Not an expert, but I think the difference is that your generator isn't configured to backfeed the grid, ever. The transfer switch simply diverts the household input from Utility to Generator and back again. So there's no danger to line workers when your generator is running.
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I'm leery of the proprietary nature of a lot of the equipment Enphase uses to do islanding.
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That's a huge peak production figure. How much energy do you typically use in a month? I just got a system with about 4-4.5kW peak installed.
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My 14kW system with 10 kWh of storage came in at $50k before incentives. In Indiana, my payback period will likely be 15 years - although as energy prices rise, the battery becomes more cost effective to time shift my generation and lower the repay period.
Pink Energy wanted 75K for a similar system but only 7.5 kWh. Energy sage only produced one quote for me from some company who didn't respond to my request to change the size up from the 5 kW he proposed. Other than asking if I lived in an HOA (I do not luckily)
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Storms, trees and overhead power lines are not the greatest of combinations. We have about 2 power outs a year, which can vary from just our block, and a few hours, to 200K customers, and 2-3 days. One could bury all of the cables, but it would take years, and be very costly. On the other hand, if you need a new hook-up, you have to pay for the feed line from the utility pole to be buried, and if you have things like septic tanks between the house and the pole, you had better be prepared to dig some trench yourself. Don't ask me how I know.
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Besides making sure your solar panels don't fry anyone working on the electrical lines, the other problem (that I don't think anyone has mentioned yet) is this: what happens if load exceeds the amount of power your panels can supply? Some equipment gets damaged if you try to run it at less than the specified voltage. I suspect this is what the "IQ" stuff is for: cutting power cleanly if the demand exceeds the supply, instead entering a "brown out".
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I'm curious to see what backfeeding 30A or higher from vehicle batteries would do to them in the long run. Depending on the circumstances, I would also hesitate to draw too much from them. If the power is out because of a snowstorm, yeah, using the car's battery to keep you warm might help, but if it is out long enough not only are you going to be left in the cold, but now you're left in the cold, can't leave (if the EV is your only vehicle), and you can't charge the car.
I think it would be better to get a generator of some sort (gas, propane, natural gas, etc) as an auxiliary power supply for homes until more 'field use' cases are made available on the limitations and expectations of backfeeding from your EV.
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I like the concept of micro-inverters, but I thought one of their challenges is that each panel needs to get to a minimum DC-output before the micro-inverter can then generate AC that is useable by the home/grid. In climates that are less solar-friendly (ex. Minnesota), an installer I talked to said that single/central-inverters were a better choice here because they aggregated all DC from all panels to get to the minimum threshold for AC generation.
The automatic grid-state detection is still awesome and I guess I don't see why this wouldn't be possible traditional inverters vs. micro-inverters. Appreciate everyone's comments and explanations on this! Still learning about solar and how we are going to move forward with it.
The automatic grid-state detection is still awesome and I guess I don't see why this wouldn't be possible traditional inverters vs. micro-inverters. Appreciate everyone's comments and explanations on this! Still learning about solar and how we are going to move forward with it.
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And even when the power lined are buried, construction works sometimes (rarely!) accidentally dig through them with heavy machinery. Have seen it happen before
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The last encounter with microinverters I had about 7 years ago was that yeah, it is a very neat idea that works great when you have a tree shading part of your power plant; or if hail knocked out half of your panels. But in anything usual (=almost all panels are working), their efficiency is lower. The end effect is that almost everyone picks one large inverter to get more electricity AND pay less than if you bother with microinverters.
Obviously, microinverters improved in the last 7 years, but non-microinverters also didn't stand still.
Also, what scheme is currently used to plug in solar in the USA? There are gazillion schemes out there, new ones keep popping up and older ones are getting banned for new installations etc etc.
Obviously, microinverters improved in the last 7 years, but non-microinverters also didn't stand still.
Also, what scheme is currently used to plug in solar in the USA? There are gazillion schemes out there, new ones keep popping up and older ones are getting banned for new installations etc etc.
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UPS’s are only designed to supply power downstream, they are not allowed to send power back to the grid. Whenever they lose grid power they have a switch that shuts the grid connection off, and then feed power downstream to the devices.
This is the same way standby generators work. They have a transfer switch which will isolate the generator and building from the grid when grid power shuts off.
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They're talking about datacenters proving the efficiency of lots of individual inverters (AC->DC in that case), but as datacenters scale don't they all move toward larger centralized DC power supplies to minimize efficiency losses/heat output? That was the original purpose of blade servers, but those have now been replaced with whole rack power supplies.
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For anyone else who wants a version of this tech, but is a shocked as I was by the price and limited options, I'll share my hack solution. We essentially put the minimal "life support" electric items in our house (networking/ security gear, built in LED lighting, WFH laptop and screens etc) on its own shadow off-grid low voltage wiring in our house. Most of it is 12 or 24v DC already, so it can run straight off a smallish LiFePO4 battery that's more than capable of keeping up those loads with a couple of 100w panels. It saves a little grid provided electricity, I guess, but mostly means you never worry about those systems going down. And since we had to run low voltage DC lines for these things anyway, it was easy to have the DC fuse panel be separate, and in a convenient spot.
That makes short outages just a minor nuisance. It isn't even always obvious when they happen. For longer outages where we start to worry about climate control and refrigeration etc, we take advantages of the fact that most electric cars, including ours, have surprisingly robust 12v systems. We installed an Anderson connector under the hood into which we plug a 1500w AC inverter to run the fridge, and/or a small AC unit/Space heater that we can use in a smallish, well insulated room. Even our ancient tiny MiEV with its small (by EV standards) 16kWh battery pack can keep those necessities going for over a day.
Currently our plan for outages longer than that involve recharging the EV somewhere with power (it's a big backup battery on wheels, after all), but you could also build up a solar EV charging option. We've considered this as an attractive way to cheapy reduce our grid use by a much more significant amount, but the obvious problem is that the EV tends to be out driving around at the peak solar generation times.
I would love if EVs were available with a more purpose built high amperage output, but it's good to know it's at least possible to sine extent already. Just be sure to check the specs on your car's DC-DC conversion system before trying it.
That makes short outages just a minor nuisance. It isn't even always obvious when they happen. For longer outages where we start to worry about climate control and refrigeration etc, we take advantages of the fact that most electric cars, including ours, have surprisingly robust 12v systems. We installed an Anderson connector under the hood into which we plug a 1500w AC inverter to run the fridge, and/or a small AC unit/Space heater that we can use in a smallish, well insulated room. Even our ancient tiny MiEV with its small (by EV standards) 16kWh battery pack can keep those necessities going for over a day.
Currently our plan for outages longer than that involve recharging the EV somewhere with power (it's a big backup battery on wheels, after all), but you could also build up a solar EV charging option. We've considered this as an attractive way to cheapy reduce our grid use by a much more significant amount, but the obvious problem is that the EV tends to be out driving around at the peak solar generation times.
I would love if EVs were available with a more purpose built high amperage output, but it's good to know it's at least possible to sine extent already. Just be sure to check the specs on your car's DC-DC conversion system before trying it.
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The transfer switch it what prevents the backfeeding of the grid, not the generator. When we built our house we installed a backup generator and wired the house specifically to support it. We have a special panel for all of the circuits that are backed up and is primarily fed by the main panel. When we lose main power an automatic transfer switch kills the main panel feed and starts the generator which feeds the backup panel. When main power is restored, the transfer switch reenables main power and shuts off the generator.
I think the magic of these inverters is that they can match the demand of the current household need instead of generating at max available capacity. Kind of like the load on the generator fluctuate based on demand instead of just running full out a max capacity. I believe with the current grid tied inverters when the grid goes down the panels go down so you have no way to recharge your battery when it is sunny outside. These invertors should give you the ability to act like an off grid system when grid power is down.
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I have a 10kw Emphases solar system, with the IQ8 micro inverters. System was installed in March of 22, when the IQ8s were brand new I was the first customer to get them from my installer. I did get a battery pack as well.
Like others posted, the system was about $50K pre-incentives, but I have my ROI at about 10 years. Since I had the system it has 'saved' me from just under 6 hours of power failure. Plus my utility bill over the summer went from ~$150 to ~$15 a mount (the electric charge is negative but I still have a natural gas connection)
Your use will of course vary but in my case, I'm super happy with the system and glad I had it installed.
Like others posted, the system was about $50K pre-incentives, but I have my ROI at about 10 years. Since I had the system it has 'saved' me from just under 6 hours of power failure. Plus my utility bill over the summer went from ~$150 to ~$15 a mount (the electric charge is negative but I still have a natural gas connection)
Your use will of course vary but in my case, I'm super happy with the system and glad I had it installed.
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This tech isn't revolutionary. Going offgrid has largely been about compliancing. Any device that can control voltage levels is a stability danger to the grid. There is VERY heavy regulation around this in Australia for example which is why VERY few solutions are approved for on+offgrid operation.I'm not sure most people will grok what a leap forward this is. Up to 50% cheaper than the existing default setup of bundled panel feeding into inverter/battery and then the grid just by a different engineering approach?
If this scales...
Question is whether this is the only company building something like this. I hope not.
It's not technically hard to make something that *can* work. But you have to prove it is stable. That takes some serious work plus ratification.
What most people don't realise is most inverters are not "grid forming inverters". e.g. a grid forming inverter can use your solar to charge your battery when the grid is down.
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Why wouldn't a more modern world just have disaggregated power generation that doesn't rely so much on the grid? Solar/battery combinations in every household would take the load off that grid and use it just for minor balancing rather than total reliance on it. It would also have the added benefit of low-cost, low-impact energy for everyone, rather than the whims of the market (ConEd just sent me a letter informing me of at 32% price increase, as a personal example). Wouldn't that be a better ideal?
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Agree - I installed a circuit by circuit transfer switch next to my main distribution panel, fed by a separate power circuit that terminates on my front porch, where I park my portable generator during an outage. I flip the individual transfer switches from line to generator one at a time, and they isolate those circuits effectively. I assume that the difference with solar panel installations is because they are designed to back feed into the grid from the get-go. They could certainly be designed to be isolating if someone wanted to build that way, but part of the financial payback of solar is based on the prospect of being able to sell excess to the grid.
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This is nothing new. I have an SMA 3.8 kW grid intertie inverter that can do the same thing. I have not used the feature yet but potentially I could hook up a few critical loads to it but would require some wiring and receptacles to be added.
Frequency is the most important part of maintaining stability for AC loads. On a partially cloudy day it will be we quite challenging to provide constant power without frequent dropouts. Not good for loads like fridges etc. It would be a nice option to be able to connect such an inverter to an EV so it can ride out these power fluctuations without actually drawing significant or continuous power from the EV battery.
Frequency is the most important part of maintaining stability for AC loads. On a partially cloudy day it will be we quite challenging to provide constant power without frequent dropouts. Not good for loads like fridges etc. It would be a nice option to be able to connect such an inverter to an EV so it can ride out these power fluctuations without actually drawing significant or continuous power from the EV battery.
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We looked at a generator setup, CNG powered, and it was about $20K. The generator was about $8K. The rest was a big transfer panel, whole house surge suppressors, and such. This had NO batteries. So, if we lose CNG upstream, we’re still screwed.
So, started looking at systems like this. Tesla? Nope. LG? Maybe. Some modular systems with solar panels are looking good.
So I believe you can buy a transfer panel and call it good. Makes your solar panels independent of the battery vendor somewhat.
Could be wrong…still looking. All so far, for a 3000 square foot house, are pushing $25-30K.
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Exactly. Suburban microgrids. Get rid of HV infrastructure for most consumers. Leave that for heavy business. Have battery banks with some sort of power redundancy but far more localised.
Every person who installs solar and batteries is paying for less of the HV utilisation. Meaning the POOR are being loaded up with the maintenance of it. HV is in death spiral.
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I guess pricing is probably regional. I got a system two years ago with 21kw of the most efficient panels w/power optimizers and 48kwh battery (3x LG RESU16H) for $70k, minus 26% federal credit for a little more than $50k total. I thought that wasn’t too bad at the time.
In the last 21 months the system has generated about $8000 in power at local rates, for about a 13 year payoff. That seems pretty good with battery included, I remember when solar was a 20 year payoff and no battery. If I’m honest though I bought it for the geek factor and I enjoy watching the stats every day and charging my car from excess solar.
I’ve heard in Australia solar is dirt cheap.
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I asked for a number with batteries and no batteries - I think the batteries were about $10k of that total. I have a pretty standard sized roof for a single family home, I don't remember the exact power target, but it would have essentially been either one side of the roof or one side of the garage depending on what was considered most efficient with respect to sun exposure.
Edit: I looked it up and I was asking for a 14 kW system (so we had the overhead to eventually switch our heatpump to electric). It was a net loss of several thousand dollars over 20 years (in a state with very favorable grid buyback). Coupled with the fact that we can pay a little extra and get 100% renewable energy from our electric company for 0.09 $/kWh and it was a pretty prohibitive to go forward. At least not as long as we can still use gas for our backup heat.
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