Grid Down, Battery Dead

[Damn Yankee]

Hi Folks, Newb here.

Big picture - grid is permanently down and my battery is dead with no possibility of replacing it.

From my research, it appears all Solar systems require a load - battery or grid or something. And I expect what kind of load depends upon what type of system. I am looking for a Hybrid as I want AC available when the grid goes down. But it seems all Hybrids require a battery, and besides backup, it seems to have to do also with voltage regulation. What happens when there is no battery, and the grid is down?

I get the simple - no power with no Sun. But what are the repercussions of a clear day, PVs have full power available, and my load is absolute minimum. What happens to the system's componentry?

With so many different manufacturers and proprietary features, it is literally head-spinning for a Newb to navigate. I've trolled the Internet for weeks for that answer. All sites presume a battery is present or generator or grid. I found only a couple sites that talked about off-grid, no battery and no generator but they were so full of typos and double-speak, I walked away with no clear answer. It seems the Solar Industry does not contemplate that the grid might go down for years or forever (thus halting battery production, oil pumping, gas refining, and everything else that relies on electricity of which we take for granted, which is pretty much everything). Either I missed a manufacturer's system with the answer buried in the hype, or this is experimental territory. Does the Danger Zone have advice, ideas, answers?

Thanks,
John

 

[OzSolar]

Welcome to the forum John,

This might be the huckleberry you're looking for. I don't have personal experience with this model or Watts247 but from what I can tell people on the forum have had good experiences with Watts247.

 

[DougfromdaUP]

A Sol-Ark 12k K works fine with no battery. I disconnect the batteries whenever I work in the box that has my bus bars.

 

[Mattb4]

Hi Folks, Newb here.

Big picture - grid is permanently down and my battery is dead with no possibility of replacing it.

From my research, it appears all Solar systems require a load - battery or grid or something. And I expect what kind of load depends upon what type of system. I am looking for a Hybrid as I want AC available when the grid goes down. But it seems all Hybrids require a battery, and besides backup, it seems to have to do also with voltage regulation. What happens when there is no battery, and the grid is down?

I get the simple - no power with no Sun. But what are the repercussions of a clear day, PVs have full power available, and my load is absolute minimum. What happens to the system's componentry?

With so many different manufacturers and proprietary features, it is literally head-spinning for a Newb to navigate. I've trolled the Internet for weeks for that answer. All sites presume a battery is present or generator or grid. I found only a couple sites that talked about off-grid, no battery and no generator but they were so full of typos and double-speak, I walked away with no clear answer. It seems the Solar Industry does not contemplate that the grid might go down for years or forever (thus halting battery production, oil pumping, gas refining, and everything else that relies on electricity of which we take for granted, which is pretty much everything). Either I missed a manufacturer's system with the answer buried in the hype, or this is experimental territory. Does the Danger Zone have advice, ideas, answers?

Thanks,
John

If I am understanding you you want a grid tie setup that works when the grid is down and without a battery or generator. The answer is you will not find such a creature. Grid tie inverters require a AC supplied sine wave to parallel with. Whether it is grid supplied or faked with a generator or even a battery inverter setup. No grid to parallel with means the micro inverters or string grid inverters simply shut down (anti-islanding protection.)

They do make off grid inverters that can work without batteries although they do work better with them.

ETA: PV does not need a load. However without a load you have nothing, just potential. Loads drive supply need.

 

[TacomaJoe]

Welcome John. I'll chime in with my two cents.

I get the simple - no power with no Sun. But what are the repercussions of a clear day, PVs have full power available, and my load is absolute minimum. What happens to the system's componentry?

No sun, no power. You can build a solar system without batteries to run your concrete mixer, but when a cloud comes by and your mixer stops, you're in trouble. Add some batteries and your mixer keeps running and you finish the new sidewalk. And also the system that you build won't work for me because I live further north. Batteries take up the slack in solar production to make the system useful.

A great solar application is an attic fan. When the sun is shining making my attic hot, the solar energy can run a fan to provide cooling. Don't need cooling on cloudy days or at night.

In my trailer I have some solar panels on the roof to charge my batteries, and an inverter to make power at night time to run my microwave.

With no grid, the best solar can do is light a bulb during the day time. Not too practical without a battery.

 

[NEpowerandlight]

Maybe you just want something like this, if AC when the grid is down is your biggest concern.

EG4 Hybrid Solar Mini-Split Air Conditioner Heat Pump AC/DC | 12000 BTU | SEER2 22 | Energy Star Certified | Plug-N-Cool Do-It-Yourself Installation

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

signaturesolar.com

 

[Damn Yankee]

Hi All, thanks for the replies.

MattB4, I don't think I said I wanted a Grid-Tie. I just wanted to be on the grid sorry for the confusion. But you said:
"They do make off grid inverters that can work without batteries although they do work better with them."
That was exactly one of my concerns. I thought the efficiency dropped so far all it did was produce heat and go belly-up.
And:
"ETA: PV does not need a load. However without a load you have nothing, just potential. Loads drive supply need."
And again, the same concern - the panels (say I did a whole-house), the DC potential could be hundeds of Volts.

To DougffomdaUP, I read those inverters had protection from that. Of course, I always pick champagne.

To most all others who replied I feel a bit better, but still worry about frying an inverter because there were no batteries. Just can't see them liking the no-load DC voltages or the output has to have some load to regulate itself. That is why I posted on this forum. You folks experiment with this stuff. I've watched videos of people starting Grid-Ties with another battery inverter, but freak out if the battery inverter would fry because it was too small a load.

Thanks,
John

 

[Mattb4]

Hi All, thanks for the replies.

MattB4, I don't think I said I wanted a Grid-Tie. I just wanted to be on the grid sorry for the confusion. But you said:
"They do make off grid inverters that can work without batteries although they do work better with them."
That was exactly one of my concerns. I thought the efficiency dropped so far all it did was produce heat and go belly-up.
And:
"ETA: PV does not need a load. However without a load you have nothing, just potential. Loads drive supply need."
And again, the same concern - the panels (say I did a whole-house), the DC potential could be hundeds of Volts.

To DougffomdaUP, I read those inverters had protection from that. Of course, I always pick champagne.

To most all others who replied I feel a bit better, but still worry about frying an inverter because there were no batteries. Just can't see them liking the no-load DC voltages or the output has to have some load to regulate itself. That is why I posted on this forum. You folks experiment with this stuff. I've watched videos of people starting Grid-Ties with another battery inverter, but freak out if the battery inverter would fry because it was too small a load.

Thanks,
John

There is a ongoing Thread from one Forum member in his journey to power directly from PV without the use of battery or AC input. https://diysolarforum.com/threads/n...olar-power-system-with-smart-switchers.48023/

Might provide some information for you.

 

[OzSolar]

The MP Solar LV6548 Inverter can do you're trying to do out of the box.

Edit:

Note: I didn't say it could do it well and I'm pretty sure it's not something I would be hooking up any loads to it that I cared about unless it was a dire situation and I was carefully monitoring things.

​

 

[Damn Yankee]

Thank you, Folks.

It is my interpretation that generally stated, inverters require a load (grid or battery) or they thermally run away.

If the system were Off-Grid, does anyone have thought as to replacing the battery with a capacitor? A charged capacitor would present as a battery that has been fully charged and forces the inverter into float mode. I think the question becomes for how long does the capacitor need to "fool" the inverter - several microseconds, a millisecond, less, more? One Farad capacitors have been around for a couple decades now for the car stereo buffs. It might be an interesting experiment to replace the battery in an Off-Grid system with one or more of the 1F caps. Thoughts?

Thanks,
John

 

[OzSolar]

It is my interpretation that generally stated, inverters require a load (grid or battery) or they thermally run away.

I know of no inverter that will self destruct if it doesn't have a load.

 

[Mattb4]

Inverters do not require a load. Grid or battery is a power source*. Inverters will not thermally run away unless the power source is unable to properly supply them. Loads on a inverter are loads on the power supply (plus inverter self consumption).

* Grid and batteries can be loads to inverter if it is a grid tie or there is a battery charger circuit.

 

[peufeu]

I get the simple - no power with no Sun. But what are the repercussions of a clear day, PVs have full power available, and my load is absolute minimum. What happens to the system's componentry?

It's really simple:

Suppose it's not a very sunny day and your panels produce 200W. That's enough to run a freezer, but it's not enough to start it.

So with a battery, the freezer can start then run. Without battery, it could run, but since it can't start, it's not going to.

If the purpose of the battery is just to power through transient high power demands for starting motors, it doesn't need to be large or expensive. It won't run the freezer at night, but a freezer should be fine with 8 hours of power a day if it is full enough.

It is my interpretation that generally stated, inverters require a load (grid or battery) or they thermally run away.

No, it's safe to run without battery. Runaway happens with wind power, if the wind turbine has nothing to brake it by drawing power, it will spin itself into pieces. It doesn't happen with solar.

However without battery, you can't use battery chargers, it has to be a hybrid inverter. And many hybrid inverters will not want to enable the backup power output without battery. But some will.

If the system were Off-Grid, does anyone have thought as to replacing the battery with a capacitor? A charged capacitor would present as a battery that has been fully charged and forces the inverter into float mode. I think the question becomes for how long does the capacitor need to "fool" the inverter - several microseconds, a millisecond, less, more?

It should work but it won't start your freezer. I mean you could get a capacitor big enough for that, but it'll be more expensive than a battery.

If you want to skimp on the battery, the safest option is to put a small one that will start your freezer, and setup the inverter for an appropriate maximum charge/discharge current so you don't overstress the battery. I've done that, it works fine, but it's not convenient. I have since then upgraded to the big Pylontechs.

 

[Doggydogworld]

It is my interpretation that generally stated, inverters require a load (grid or battery) or they thermally run away.

Off-grid inverters actively control the amount of power coming in.

They're generally designed to control power coming from a battery. Solar panels respond differently than batteries, so it's not usually a great idea to hook panels directly to an inverter without a solar charge controller in between. All-In-One units, like the MPP LV6548 mentioned above, have internal MPPT controllers with algorithms specifically designed to control solar panels. So if you want to run multiple household loads off solar you probably want an AIO instead of a simple inverter.

Some AIOs support battery-less operation, some don't. It comes down to the way the internal MPPT and inverter communicate and what size capacitors they have to handle transients like motor start surges and people suddenly turning things off.

If the system were Off-Grid, does anyone have thought as to replacing the battery with a capacitor?

Probably better to buy an AIO with sufficient internal capacitors, but people often hook external capacitors (aka soft-starts) to motors that draw high surge currents, e.g. well pumps, AirCon compressors, etc.

The bigger problem with battery-less operation is low input power due to clouds passing over or whatever. The AIO will trip every time solar output drops below your load. That can happen dozens of times per day in partly cloudy conditions. An external capacitor big enough to ride through clouds would cost a lot more than a battery.

 

[Damn Yankee]

Thank you for the additional information. Perhaps my seemingly stupid questions are because I have not been clear of the initial conditions.

Those conditions are:
1) Grid goes down either permanently or perhaps a year. It takes ~3 months to build a transformer and the laminations are a special steel called Electrical Steel available from China.
2) I live in rural Appalachia and will be close to last to get service should it be restored.
3) I have to have water to survive and my well is 750'. There is no mechanical device that has a 750' head - 300' max. So, I need electricity to run the well pump.
4) At some point the batteries die and cannot be replaced for reasons 1 and 2 above. That is, I have no batteries.

Under these circumstances, what are my options?

Hope that helped!

Thanks,
John

 

[Mattb4]

Your best option is to create a rain harvest collection system. I suply my water this way and have for over 25 years now. I live in rural Arkansas and get plenty of rain fall that is collected (after diversion and a sand filter) into 3 - 1500 gallon tanks and than pumped into my home with a 1/2hp surface jet pump and pressure tank. The tanks are buried up to their lids in the ground to prevent freeze damage. They are also at a higher elevation than the home even though buried so there is some flow even without pumping.

I also have a very deep well of over 800ft that I can use with grid power. I rarely do so.

 

[SparkyJJO]

You get batteries and you hope they are not totally dead at exactly the same time that the grid explodes. Odds of both are reallt not that high. Even if your batteries are degraded you have aome indication this is happening and could remediate, or if grid blows and you have degraded batteries they'll still be somewhat functional in most cases.

 

[MurphyGuy]

Enphase IQ8 will provide the full available power of your solar array when the grid is down without a battery.

But when the sun goes down, so does your power.

 

[peufeu]

Under these circumstances, what are my options?

I kinda built a similar system, but ended up changing it, for quite simple reasons:

If I don't use the thing often enough, I will forget to maintain it, so when I need it, it won't work. And a system designed only for blackouts absolutely fits this description. It's like a gas generator: when you need it, if it didn't have proper maintenance and regular starts, it won't start, or the gas that was left in it turned into mud.

Another problem with a system that isn't used often is sometimes breakdowns occur after a little bit of use, and these "early deaths" are not discovered until you need it and it breaks down.

So I realized there was no way the batteries would still be alright when I'd need them, and besides I wasn't monitoring their state because I wasn't using them. And the inverter was cheap junk.

So I'm going to sell all this stuff. I'm telling you this so you don't waste your money like I did! Instead I just put in 24 more panels and a hybrid inverter with big pylontechs. It's working right now. The nice thing about this is I use this system every day, as the batteries store solar energy during the day and feed the house at night. I'm not offgrid, that would need many more panels. When the batteries are discharged, it simply uses the grid.

So, as it gets used, I always know if it's working. The inverter displays battery state of health, so I can monitor them. And a system that has been running for a while has less chance of breaking down that one that's being used for the first time. Then of course, probability of failure increases as the equipment ages, but the typical failure rate versus time is a "bathtub" curve: early deaths, then it works smoothly, then it dies of old age. I still installed two inverters and two batteries, everything is redundant, just in case.

And it's going to substantially cut my electricity bill, so it is not an expense for a "what if" scenario, rather a mildly speculative investment, that protects not just against an unlikely blackout, but also against the inevitable rise of energy costs. I'm French, we're very concerned about that at the moment.

In the same spirit, I'm insulating the house, which also tackles both blackouts and rising energy costs.

 

[Zwy]

Thank you for the additional information. Perhaps my seemingly stupid questions are because I have not been clear of the initial conditions.

Those conditions are:
1) Grid goes down either permanently or perhaps a year. It takes ~3 months to build a transformer and the laminations are a special steel called Electrical Steel available from China.
2) I live in rural Appalachia and will be close to last to get service should it be restored.

No need for grid tie system, setup off grid.

3) I have to have water to survive and my well is 750'. There is no mechanical device that has a 750' head - 300' max. So, I need electricity to run the well pump.

Well can be 700 feet but where is the pump set at? A 700 foot head is quite a large head.

4) At some point the batteries die and cannot be replaced for reasons 1 and 2 above. That is, I have no batteries.

Under these circumstances, what are my options?

Some pumps can run entirely off solar. Storage required for days of low solar output. Much easier to handle all of this with batteries in the system.

Hope that helped!

Thanks,
John