diy solar

diy solar

dual solar panels

den19420

New Member
Joined
May 16, 2022
Messages
21
I have 12 panels on my roof. I have recently learned that my PUD shuts power from my panels to the grid when they lose power.
The installation was designed to relieve power outages but that does not seem to be the case. At least in my PUD area.

Are there ways to disconnect panels temporarily during a power outage and put them to work charging separate batteries for the time of the power outage. It seems a few panels could be used to keep refrigerators and computers running without touching the PUD circuit. I would reconnect to the grid when power is restored.
Any thoughts would be appreciated.
 
Difficult to answer you question with so many details missing.
You mentioned charging separate batteries? If your system already has batteries is it a DC coupled system? If so the panels should continue charging the existing batteries unless they are full already. Perhaps the inverter is not programmed properly to support back up power?
It sounds like you may have a grid-tie system not a back up system and the Rapid Shutdown module(s) are disconnecting the panels in a grid outage situation. Please provide additional details and model numbers of your existing equipment.
 
On one of the threads around here recently somebody was arguing that most grid tied customers did it for the financial benefits of shaving their electric bill and not for home backup during an outage.

I was going to argue that from what I've seen, many grid tied people don't realize their solar panels do nothing for them when the power goes out.. and then a few days later, here is an example, in the flesh.
 
I was going to argue that from what I've seen, many grid tied people don't realize their solar panels do nothing for them when the power goes out.. and then a few days later, here is an example, in the flesh.
Its certainly true that solar sales persons DO NOT mention these facts unless specifically asked. However, based the original post we don't know what kind of system the customer thought he paid for and didn't get or perhaps did get is capable of back up but not configured properly or faulty.
 
Its certainly true that solar sales persons DO NOT mention these facts unless specifically asked. However, based the original post we don't know what kind of system the customer thought he paid for and didn't get or perhaps did get is capable of back up but not configured properly or faulty.
You'll get no argument from me on those points. We can't help the OP except in the vaguest sense without more info, other than to say to the original poster :

@den19420
Yes, it's possible to disconnect/switch the panels and do what you are talking about during an outage.. but without specific info on your equipment, and maybe some photos of how it's installed, we can't answer you as to how.

Most likely you have a properly permitted and grid tied system that uses whatever electricity it produces locally (at your house) and if it has excess sends it the power grid either for credit to you on your bill, or for free. It is synchronized with the utility grid and if it didn't shut down when the power goes out, it could possibly electrocute a utility worker while they try to fix the problem.

If this is the case, messing with it in anyway would probably be a violation of the permits with your city/county and possibly the agreement with the utility company. The solar panels could also be in one relatively high voltage DC string, and messing with them could be dangerous, please don't try to disconnect or alter them in anyway until you are 100% sure of what they are and what you're doing with them.

Once we know what equipment you have, we can make more useful recommendations.. so please give us some pics and specs.
 
I'm back with more details.
1. I have 14 panels. Silfab 370BK, total of 5.8KW (370 watts each). This Bill of Materials was intended to satisfy 100+% of my power needs in Seattle, Wa. They took readings from the roof to measure exposer and extrapolated the 12-month average.

2. I did not buy battery backup. I understand that batteries are a storage medium, but I assumed (wrongly) that even without batteries, I would enjoy power every day the sun came out. I expected to have power regardless of PUD status. I did not care about power consumption when the sun went down. Finally, the pack of lithium batteries needed to provide "off grid" balance, when the sun was less optimum, would double the cost of the system.

3. When I learned, months later, that my solar panels would not provide power when the PUD went down, I was a) pissed because this business about the PUD being unwilling to work on lines that might be "live" with nearby solar systems, was never discussed. And, b) I can think of a bunch of ways to mitigate that problem.

4. When I reconciled that I was dealing with a political issue that might deprive the PUD of my power whenever I wanted to use it, I considered ways to pull down the solar panels, which I am able to physically switch off the grid, and run them to an outboard pack of batteries sufficient to power a refrigerator and a few appliances. When I pull the panels down on a separate circuit they will not flow toward the PUD.

That's where I am now. I believe I can connect 2 or 3 panels on my side of the switch, and feed those panels to a commensurate number of lithium batteries. This power will be physically separate from the grid tied to the PUD. I shall only use these panels during an outage. A large toggle switch currently exists near my power meter. I assumed it was installed for this purpose. I suspect I can switch back to PUD on the same toggle switch when power is restored. Any help would be appreciated.
Denny
 
@den19420

Now that we know what type of panels you have, we need to know what type of inverter you have.

The DC from those panels is being converted to AC somewhere.

You either have panel level microinverters installed either on each panel (underside usually), or being shared between 2-4 panels, again, probably on the underside of the panels somewhere..

.. or those panels are supplying what is likely very high DC voltage to a string inverter located on the side of your house somewhere with a metal conduit going into it, it might even say on it something about high voltage dc with a big warning sticker.

Once we determine what kind of inverter(s) you are using, we can proceed to inform you what your options are.

A picture of the side of your building with all the equipment on it would help tremendously, if you can swing it.
 
Thanks for the help.
The inverters are EnPhase IQ 7+, 295W, 14 devices, 96% efficient.
The inverters appear to be mounted under the panel nearest the junction box. I believe all the lines run to the box. That box has a manual on/off switch marked emergency power off.

Hope this helps.
Denny
 

Attachments

  • IMG_3286.JPG
    IMG_3286.JPG
    69.6 KB · Views: 9
  • IMG_3288.JPG
    IMG_3288.JPG
    75.5 KB · Views: 9
  • IMG_3287.JPG
    IMG_3287.JPG
    76.7 KB · Views: 9
Enphase offers a battery back-up product(s) that would integrate with the IQ7+ series, this is the most expensive option. Or you could go with an AC coupled hybrid inverter using any brand that is UL1741SA compliant.
 
assuming I go for the less expensive option. What am Doing? Do I take the output of the Enphase IQ7 and run that to UL174....compliant thing? Does that then connect to a battery? Does this battery, and then go to an inverter? I'm sure I'm missing something..
 
assuming I go for the less expensive option. What am Doing? Do I take the output of the Enphase IQ7 and run that to UL174....compliant thing? Does that then connect to a battery? Does this battery, and then go to an inverter? I'm sure I'm missing something..
Its a really big subject to cover. I would recommend spending a couple of days researching AC coupling. Use this forum and Google. Then come back and ask the questions that you still need answered.
 
@den19420

That is some good equipment you have there, but it's not going to be quick and easy to mess with. That is also very likely a permitted, and properly inspected install. Whether you want to risk messing with that stuff without an additional permit is up to you.

Microinverters like that are nice pieces of equipment with some advantages and disadvantages. The main advantage is ease of installation, independence of each solar panel to do it's own thing as far as solar production goes, and safety.

The main disadvantage is that it's coupled to an AC source which it then syncs up to. That's also an advantage, depending on what you are trying to do. But for DIY stuff, like what you want to do.. not so great.

You would have to get a UL1741SA compliant inverter/charger (example) which would AC couple to the combined output of those enphase microinverters. It would manage them by becoming the "utility" company as far as the enphase equipment is concerned. When the utility company is up, everything would function much as it does now. When the utility company goes down, the UL1741SA compliant inverter/charger (which would need to have some batteries) would generate an AC signal of it's own to manage those enphase microinverters so they continue producing and use their power locally at your house.

It's not going to be as simple as just splicing something in and being done though.. to keep it all legit and to code will require another permit most likely and inspection.. along with some electrical work. I don't pretend to know how to explain all that has to be done to hook it up, I'll let somebody else handle those types of details.

edit.. it's important it be done legit and to code if you have a mortgage / homeowners insurance. If you do anything wrong, and anything is ever found to link back to your non legit and not to code work, the homeowners insurance will cover nothing.. and you'll likely receive a stern talking to from somebody in power in your county/city.

I know you're upset by not having power from your panels when the utility goes down, but things could be worse, your house could burn down and you get no insurance payment.. or you try to sell it and the inspection determines you have non permitted work on a solar system and it has to be brought to code before you can sell.. derailing the whole sale for however long that takes, plus the butt whooping the city/county would give you for running non permitted modifications.
 
Last edited:
Next question in the list is how long do you want backup? You would likely need about 20kWh of battery to make it minimally invasive if you lose power during the summer, but in the winter I would expect you to need to ration power some.

A 20kWh battery system will run you $7-20k depending on who you buy from; the mainstream commercial installers will quote you something on the high end of that range. Then you need a second "Hybrid" inverter, which will likely be around $5,000 equipment cost. The electrician's time should be another $3,000, give or take. Permitting the project would be about $1,000. Then there is the contractor's overhead and profit, which could double the cost. All in, I don't think you could do it for less than $20k today.
 
Well, this was very enlightening, which is what I wanted. My take-away is that there is far more to loose than gain.
Risking my health, solar warranty and possible litigation, I think I'll stay put. As it happens I am already working on a modest Solar system that I am collecting data on right now. It's complete and separate. I want to operate a refrigerator, a computer and a few portable LED lamps for 48 hours. That I understand. Panel + Regulator + Inverter + Load. That will do the job for now Perhaps someday the PUD will work with Solar Companies to automate their switching technology and change the law. Although, I still feel the PUD will not concede willingly so long as they can harvest my power for free.
Well done to those who contributed to my education.
Denny Carroll
 
@den19420
If it makes you feel any better, the PUD probably doesn't want your power from your solar panels. For a variety of complex electrical reasons that I barely comprehend, they hate us home solar users and we make their job more difficult, far beyond what the electricity they manage to get from us is worth.

I don't know if you have an agreement where you get paid for the electricity you generate, but if you do, bravo, you're sticking it to them.

If not, just be sure to try and use as much electricity as your panels are making through whatever means you can come up with. Example, run a bitcoin miner or etherium miner, but only up to the point of what your panels produce and then shut it down when your production drops. That way your generated electricity is not leaving your home and going to the grid.

Maybe someday prices will drop on properly permitted UL1741SA compliant equipment and batteries.. if so, you could get AC coupled then. Your equipment on your roof/wall is really high quality stuff.. it's not going anywhere and should still be perfectly AC coupleable down the road.

Building your own small solar system as a backup for your fridge and computer and led lamps is a good way to learn. You will then also have a better grasp of what's going on your with grid tied system and can make educated decisions about it in the future.


back to the crazy stuff..
The panels on your roof are completely functional with other solar systems using string inverters, you would just have to not use the enphase microinverters by diconnecting the MC4 connectors from the panel to the inverter and run an mc4 cable down to your own traditional inverter instead. Because each microinverter operates independently of the others, it shouldn't even cause the whole enphase system to stop working. Be absolutely sure the panel isn't HOT while you do it though, cover it with something so it sees no light, and turn off all the panels at that "rapid shutdown for solar PV" box. You might also want to make sure power to/from your utility grid is off at the main breaker as well, but that's probably not necessary as I would think that rapid shutdown is supposed to sever the AC connection from the microinverters/panels to the rest of the system.

Taking some of your panels offline might flag your system (through Enphase built in monitoring) to your installation company though and they might ask about your panels being down and want to come service it, I don't know how reactive they are to detected equipment failure.

Messing with it like that will be frowned upon though and if not reversed back quickly will open you up to liability if something bad happens, but if in a power outage or something, and you want extra power, you could do that and hook them up to a string inverter down below, say your custom portable system. It would need to be a long power outage to justify the work though.. like end of the world length of time power outage in my mind.
 
It is a legit safety issue, your micro-inverters are "only" producing 240v but that will go through your nearest transformer backwards and become 11,000v and hence is a serious safety issue for linesmen as you can imagine. Also you will be trying to power the neighborhood !!!! Its called Anti-Islanding.
Now all is not lost, simple solution is to get an inverter and batteries sized for the loads you want to run during a power outage and connect it's input to your house, then you are charging your batteries with your own power !!!! In a round about sort of way.
 
It is a legit safety issue, your micro-inverters are "only" producing 240v but that will go through your nearest transformer backwards and become 11,000v and hence is a serious safety issue for linesmen as you can imagine. Also you will be trying to power the neighborhood !!!! Its called Anti-Islanding.
Now all is not lost, simple solution is to get an inverter and batteries sized for the loads you want to run during a power outage and connect it's input to your house, then you are charging your batteries with your own power !!!! In a round about sort of way.

Can you install a generator port and cut off switch at the main breaker on a house with an enphase system and couple with the enphase equipment using an fuel based inverter generator or regular old inverter and battery? I thought I saw something around here saying the microinverters might overwhelm the inverter or generator in some way.
 
NO, a conventional generator has no way to manage the power fluctuations from the microinverters, you will most likely produce a large puff of smoke and destroy the generator. AC coupling with a suitable UL1741SA battery-inverter that has an internal transfer switch is the proper way to use grid-tie inverters when there is no grid.
 
NO, a conventional generator has no way to manage the power fluctuations from the microinverters, you will most likely produce a large puff of smoke and destroy the generator. AC coupling with a suitable UL1741SA battery-inverter that has an internal transfer switch is the proper way to use grid-tie inverters when there is no grid.
That's what I thought, bummer. Lousy microinverters. :cry:
 
Back
Top