Grid Down, Battery Dead

[Damn Yankee]

I appreciate all replies. I think a few understood what I was saying but I think many do not get the point if the grid is down for any time more than a month, there will be no gasoline pumped, no stores will be open or will already be raided due to the anarchy that will ensue - THAT MEANS NO BATTERIES.

Mattb4, once again thanks for your input. That is exactly where I started - collecting from every downspout from our metal roof. The cons of that system led me to a mechanical pump (which won't work) to running the current well pump with Solar even if it was only when the Sun allowed. Unfortunately, that led to why not heat and why not hot water, and why not... Suddenly, it became whole house.

MurphyGuy, I discovered the IQ8 about 1/2 hour ago as well as a few other solutions. I think the secret sauce was Googling "what hybrid inverter will not destroy itself without a battery and no grid". There were several solutions (brands) offered. Thank you.

To Zwy, yes. Unfortunately, my pump is at the end of 750' of galvanized.

To those who offered run the batteries till they are dead and maybe they will offer some protection, I agree with that position. Open or dead short will be my only enemy, otherwise even dead batteries with no capacity present a load. In the case of having battery backup, I would probably not do lead-acid, rather a used electric car battery and charger for it. The price for used batteries is surprisingly reasonable, and certainly my nightly and Sunless days demand would be curtailed if the SHTF. In that case there is a high possibility that battery would outlast any other solution especially since I can circulate coolant through it. After all, heat is the biggest enemy to batteries.

Thank you all for your thoughts and ideas. They make me think.

John

 

[Mattb4]

I appreciate all replies. I think a few understood what I was saying but I think many do not get the point if the grid is down for any time more than a month, there will be no gasoline pumped, no stores will be open or will already be raided due to the anarchy that will ensue - THAT MEANS NO BATTERIES.

Mattb4, once again thanks for your input. That is exactly where I started - collecting from every downspout from our metal roof. The cons of that system led me to a mechanical pump (which won't work) to running the current well pump with Solar even if it was only when the Sun allowed. Unfortunately, that led to why not heat and why not hot water, and why not... Suddenly, it became whole house.

...

Never let the perfect be the enemy of the good.

BTW, there are several battery types that have rather long life spans. These new fangled LiFePO4 are rumored to be upwards of 10 years or more. If you survive the end times for ten years before the lights die I would call that a win. If civilization has not returned by than you should have had sufficient time to come up with new ways of living.

 

[OzSolar]

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.

That does not agree with what I've read on Enphase.

Enphase recommends your backup loads do not exceed 30% of the total rated AC output power of the IQ8 Microinverters on the roof. For example, the rated power output for a system with 24 IQ8 Microinverters is 5.7 kW AC. The backup loads should not exceed 1.7 kW AC (30% of 5.7 kW AC).

 

[MisterSandals]

I think many do not get the point if the grid is down for any time more than a month, there will be no gasoline pumped, no stores will be open or will already be raided due to the anarchy that will ensue - THAT MEANS NO BATTERIES.

To me, if all these things happen, that means batteries are king. Especially long lived LiFePO4 batteries.

 

[SparkyJJO]

I appreciate all replies. I think a few understood what I was saying but I think many do not get the point if the grid is down for any time more than a month, there will be no gasoline pumped, no stores will be open or will already be raided due to the anarchy that will ensue - THAT MEANS NO BATTERIES.

You buy the batteries (and all other equipment) before said apocalypse. Then if that does happen, you DO have the batteries already.

 

[peufeu]

By the way, are there any inverters that will actually blow up if the battery is disconnected?

 

[MisterSandals]

By the way, are there any inverters that will actually blow up if the battery is disconnected?

An inverter with a battery connected, going to an inverter with nothing connected seems pretty safe.

 

[MurphyGuy]

That does not agree with what I've read on Enphase.

Enphase recommends your backup loads do not exceed 30% of the total rated AC output power of the IQ8 Microinverters on the roof. For example, the rated power output for a system with 24 IQ8 Microinverters is 5.7 kW AC. The backup loads should not exceed 1.7 kW AC (30% of 5.7 kW AC).

Good point. Still better than the Secure Power Supply options offered by companies like SMA.

Battery-less backup systems are a waste of effort anyhow. No battery = bad experience.

 

[peufeu]

An inverter with a battery connected, going to an inverter with nothing connected seems pretty safe.

I mean they all recommend to install a battery disconnect switch, so it would be quite unfortunate if that also acted as a self-destruct...

When I turn off the battery switch, my Solis shuts down the backup output, even if there's enough solar to actually power it. The firmware is a bit dumb. I don't see any reason a hybrid inverter couldn't run without batteries besides the firmware being dumb. The only thing that could break would be the output relay due to too much cycling on and off when it doesn't have enough solar to power the load.

Grid tied inverters can't run without grid, of course.

 

[MisterSandals]

When I turn off the battery switch, my Solis shuts down the backup output, even if there's enough solar to actually power it.

My understanding is that this is bad, and sometimes will kill an inverter. Not sure it would blow up as you were asking.
Consult your manual an see if they recommend against disconnecting battery while solar charging.

 

[OzSolar]

To me, if all these things happen, that means batteries are king. Especially long lived LiFePO4 batteries.

So I have a 23 year old flooded lead acid battery bank that is still pretty stout. 2V Surrette cells. We're grid tied now so it's in float mode most of the time but I when I do cycle it down and charge it back up all of the cells behave very well. Volts and SG's are spot on all the way around. I recently installed a Victron Smart shunt so when longer days get here I'll attempt a capacity test but I suspect it's around 75% capacity.

My case is an outlier I know but what % of LiFEP04 banks are going to make it to 15 years? 20? I would love to know.

I seem recall that very knowledgeable folks on this forum and elsewhere have mentioned that calendar much past 10 years is going to be pretty tricky due a variety of factors. Something about dendrite growth? Way over my head of course.

People talk a lot about active cell balancing and not storing LiFEP04 at 100% for maximum life but what else are going to be the keys to getting a long life from LiFEP04.

 

[Zwy]

To Zwy, yes. Unfortunately, my pump is at the end of 750' of galvanized.

Start here. https://diysolarforum.com/threads/best-inverter-for-deep-well-pump.5388/post-273078

850 feet of head is possible.

 

[OzSolar]

Start here. https://diysolarforum.com/threads/best-inverter-for-deep-well-pump.5388/post-273078

850 feet of head is possible.

The pump may be 750' but what is the static water level? Something less than 750' I suspect.

We just did a Grundfos SQF so I had this chart handy. You can run this pump directly off solar. No batteries required. It would take ~1.4 kW of modules.

 

[Damn Yankee]

Sorry for the tardy reply; work, you know...

I have continued my research. Much confusion and time revolved around a Hybrid/Off-Grid solution with no batteries. The stance on so many forums was unused potential of the array had to go somewhere, therefore you needed batteries. I railed against that notion for This mindset went against all my training, experience, and Physics. Now, fully confident that the only danger of damage comes from the Open Circuit Voltage of the array vs the inverter input, I've realized most people haven't a clue, only a keyboard, and I can continue.

I am looking at a worst-case scenario - no grid forever. Living in rural East Tennessee, even if the grid was hobbled-up in three months, I doubt very much us hicks would be top priority. What my requirements are:

1. Water
2. Microwave
3. Hot water heater (even tepid water)

In that order. My pump is the only device to support a 750' head. It is 1 1/2 HP = ~1,119 W. Allowing for start-up I figure 2K W total is required without batteries. Rather than push the inverter I would upsize by 1.5 making it 3.5 KW. And because I want to run some other conveniences, I am thinking a 5 KW system is the target. Space is no object, the panels will be mounted on the ~45-degree hill, facing due south in front of the house. As water is my primary need, I consider the pump may fail so rain barrels would be water back-up off the steel roof.

So, what inverter? There are very good ones out there. I like Sol-Ark, but the price makes me gag. Even Caddies and Teslas break down. If that bad boy dies, so do I, therefore a back-up is required. What does the Forum think about 2 (or 3) cheapies from China?

Thanks, All.
John

 

[Mattb4]

I would suggest you have a dedicated solar setup for your well. I would also suggest that you pump from the well to a storage tank on the surface instead of a pressure tank to reduce load requirements. From this tank you can use a DC on demand water pump to supply your home.

In terms of what inverter for your home needs (not the well) I would suggest you decide on what you can spend and also on what minimum loads you need to supply. Supplying any form of electrical heating, water or other, is going to require a great deal of wattage. There are many passive solar water heating designs that can give you hot water. All it takes is some black pipes in the sun for a few hours to get water hot enough to scald. I really suggest you price in a few batteries to smooth out the PV interruptions.

 

[Damn Yankee]

I would suggest you have a dedicated solar setup for your well. I would also suggest that you pump from the well to a storage tank on the surface instead of a pressure tank to reduce load requirements. From this tank you can use a DC on demand water pump to supply your home.

In terms of what inverter for your home needs (not the well) I would suggest you decide on what you can spend and also on what minimum loads you need to supply. Supplying any form of electrical heating, water or other, is going to require a great deal of wattage. There are many passive solar water heating designs that can give you hot water. All it takes is some black pipes in the sun for a few hours to get water hot enough to scald. I really suggest you price in a few batteries to smooth out the PV interruptions.

Thanks Matb4,

Your previous thoughts have been helpful. Regarding the solar heated water, I though about that and the cost of copper pipe. I would have to do an analysis of copper/reflector vs PV. But I have geothermal. Both hydronic and forced air. The forced air would shut the panels down immediately, but the floor unit would probably start with enough panels. I have the area for as many panels as I can afford. I need first analyze how quickly the slab will give up its heat and how long the heat pump must run to heat it back up.

I hope I'm not labelled as a nut-job here, but this is a solution for never having a grid again (man, they are experimenting already to take it down). A transformer is custom and takes months or more to build. It is made with Electrical Steel - to my knowlege only available from China. Then it has to be transported by rai and truck to the substation. In the time it takes, this country is in full anarchy and it will not get done. No electricity means no gasoline, no batteries - thus the no battery configuration.

Just your local nut-job...

 

[SparkyJJO]

I get it, crossed my mind too. But trying to do it totally without batteries may be more difficult than it is worth. Even having a worn out battery that has 10% of capacity is better than none at all, and can help smooth things out and at least make things work through a brief cloud passing by.

 

[Damn Yankee]

I get it, crossed my mind too. But trying to do it totally without batteries may be more difficult than it is worth. Even having a worn out battery that has 10% of capacity is better than none at all, and can help smooth things out and at least make things work through a brief cloud passing by.

I thought about that too. But let us say I live another 30 years and it happens in the next year or so. Best I can expect from tending over brand-new batteries like a mother hen is 5 - 10 years. Then use them until they have no capacity at all. Full open or worse, full short. Can't have spare new batteries for dry, shelf life is what, 3 years? Flood them and then they sulfate as they sit around. No win...

 

[Mattb4]

Thanks Matb4,

Your previous thoughts have been helpful. Regarding the solar heated water, I though about that and the cost of copper pipe. ...

Black plastic pipe or even black painted galvanized steel pipe could be used.

Decades back when I was working on my first homestead and living on unimproved rural property I had no means of heating water for showering. Once the well was drilled and water was pumpable (at first with generator power) I ran two 100ft 3/4" black garden hoses to a quickly 2 x 4 framed, tarp sided, shower stall that I connected the hoses with two butterfly disconnects, a Y, and than a shower head. Using this I had a hot shower by carefully running enough water out of one hose to get cool water to mix with the hot water from the other hose. The shower was open on the one side and I used a simple plywood floor to stand on.

It worked for me and avoiding driving into town and paying for a shower many days.

ETA: Digging out my USABluebook Operator"s Companion Book I see that there is .023 gallons per ft of 3/4inch pipe. So my 2 hundred feet of garden hose would give me around 4 and 1/2 gallons to use.

 

[Doggydogworld]

I thought about that too. But let us say I live another 30 years and it happens in the next year or so. Best I can expect from tending over brand-new batteries like a mother hen is 5 - 10 years. Then use them until they have no capacity at all. Full open or worse, full short. Can't have spare new batteries for dry, shelf life is what, 3 years? Flood them and then they sulfate as they sit around. No win...

Nickel iron batteries last 20 years and can be refreshed with new electrolyte.

Solar panels degrade. Inverters blow every decade or so. Your well won't last forever. Your microwave could die after 17 years, like mine. If you really want long-term reliability choose rain water collection and wood heating.