How can I disconnect from utility in event of power grid melt down?

System

I stumbled onto this site when I Googled, "How can I bypass utility?"

I live in Tucson and had a 6k solar system installed 18 months ago. I don't have battery storage so the system only produces electricity when the sun shines - which is most of the year. One thing I have wanted to know:

Because our system is tied into the utility and is equipped with a shut-off in the event of a power black-out, is there some way I could circumvent this shut-off in the event of a "major," long-term power outage (such as the grid goes down completely)?

I have virtually zero technical/electrical skills, so I'm looking for something like, "Bypass the Utility for Dummies" instructions.

I would only do this is a worst case scenario but I don't want solar panels sitting on my roof and NOT be able to use them to power our house at least during the daylight hours.

So, is this possible? Thanks.
~SKWright

icarus

Re: How can I disconnect from utility in event of power grid melt down?

It can be done,, but it is very expensive. Special inverters,, plus a very expensive battery bank (that will sit idle 99.9 % of the time. Your money is generally much better spend buying a good back up generator. (Unless your particular grid connection is really unreliable).

Question is, how many times in the last say 10 years has your grid gone down,, and for how long? How much are you prepared to pay to have the lights on during those times?

Tony

PS Welcome to the forum. There are some very smart folks here who are all too willing to help,,, folks that forgotten more about PV than most of us will ever know.

PPS. the short answer on how to bypass the grid for dummies is,, don't.

T

BB.

Re: How can I disconnect from utility in event of power grid melt down?

Your best bet is to decide what the minimum use of power you can live with... No A/C? No central heat? etc...

If you can get your power usage down to were you can live with a 1,600 watt genset (i.e., fridge, possibly freezer, some lights and small tv/laptop computer, use natural gas for heating, cooking, hot water, etc.), then a genset becomes a pretty easy and inexpensive way to have 5-10 days of backup power.

That was my choice--Every way I looked at a power outage--Our power was too reliable and the maintenance costs of a battery, extra charge controller, off-grid inverter, etc. just did not make economic sense.

Instead, I bought a (now) $1,000 Honda eu2000i (1,600 watt peak) and 25 gallons of gas + Fuel stabilizer. Have not had to light the thing off ever (in 7+ years at this house). I also put a small/less expensive manual transfer switch in my home that I can use to power a few circuits (fridge/freezer/lights/couple of outlets). And I put the fuel back in the car and refill the cans once a year (lately, that has been my best investment--buy fuel at $2.85 a gallon and today it is worth $3.60 a gallon:roll:).

Figure I can live pretty nicely on ~2 gallons of fuel per day--or almost two weeks (+siphoning car). Plus, if I need to bug out (earth quake country here)--I have 25 gallons of backup fuel for the car and I can even haul a 50lb genset with me to the next location. Cannot take my 3.5 kW of solar panels and the 1-2,000 lbs of batteries I would need if I had hybrid/off grid solar. Plus, for us, there is always the chance that the house gets condemned from the earthquake. Which would make the off grid solar a questionable deal too.

As Tony/Icarus says--You really need a good reason to put your home on a whole house solar UPS. And need (very roughly) to replace the battery bank and all the electronics every ~10 years.

Not saying that your needs for off grid/hybrid solar are the wrong choice--just that I made a different one with my home.

-Bill

niel

Re: How can I disconnect from utility in event of power grid melt down?

as to a grid meltdown you are talking a long term outage that you want to prepare for. the generator will work as long as you have gas, but those gas stations will not be pumping gas as they won't have power either so once your supply is done so is the generator power.

what i think could be done is a backups type arrangement so you have some key critical things being power by a sine wave inverter and batteries. the problem here is once the power is gone the countdown on the batteries has started and you don't want to deplete them farther than 50%. what you might do is tap your pv system at a suitable point to feed a high voltage mppt controller that goes to the batteries. this will not power your whole house or the few critical circuits 24/7 either, but may prevent food spoilage if power usage is spaced out. add to that a generator and you could survive fairly well for some time.

for those that would yell about efficiency, the backups would still be maintained by the solar as long as the sun shines. when it doesn't shine the excess that went to the grid is now starting to be used, but it most likely won't take much back from the grid as the float charges would be fairly small.

there are a few high voltage mppt controllers out there, but the only one that is in line as far as costs go is the classic. the inverter on most gt systems can get fed in the area of 300v to 500v from pvs and the classic 250 can go to 250v. this would mean a tap at the point where the pvs total voc is less than 250v would suit fine (for classic 250 model), but be sure the outputted current won't be exceeding the controller's cutoff current after downconverting as it would then be wasted power. the tap can go lower in voltage and if low enough it could fit into another category of classic controller and would gain a tad of current output capability.

this can get complicated to implement, but would be doable if no certification violations would be breached in doing it. one would have to leave the tap disconnected as long as the grid is active and when an outage is present a break in the gt inverter connection might be advisable too as power may come back on in the meantime.

GreenerPower

Re: How can I disconnect from utility in event of power grid melt down?

An option is to move all critical loads to a sub-panel. This sub-panel is connected to the main via transfer switch like the Iota so that it would be disconnected from the main when the grid goes down. The existing grid-tie would connect to this sub-panel. A battery-based grid tie like the SMA inverter could power this sub-panel in an event of a power outage. PV power still can be used this way and the SMA inverter would "throttle" the PV inverter according to loads. A standby DC generator or AC generator+DC charger for long term outage.
My settings are basically this way except the PVs are to charge battery or to sell via the battery-based gid-tie inverter instead of grid-tie. My battery bank is small (48V 100AH). My generator is standard AC generator (5KW from HomeDepot) with adaptor installed to make it tri-fuel - gasoline, natural gas and propane. Proved to be handy during Ike hurricane where power was gone for 2 weeks.

GP

Blackcherry04

Re: How can I disconnect from utility in event of power grid melt down?

I have to agree with the Generator. I bought one 15 years ago after a couple day power outage. I installed a backfeed Breaker a 240V outside waterproof receptacle. I left the generator in the box and never started it for 9 years. Then we had a Ice storm that took down the Power lines. I got out my untested Generator out, filled it with gas and it started on the first pull. I cut the main breaker and plugged up my adapter cord and plugged the generator in and after qualifying the voltage, I energized the backfeed breaker and had all the power I needed. I had enough Gas in my cars and trucks Plus 10 gal in cans to keep it going for 5 days. I didn't run it 24/7 and never planned to, I'd run it for about a hour every 2-3 hours.

When I de-engerized it, I drained the tank, lines, took the carb apart and removed all the gas completely , blew it all out with air. Pulled the plug and put a teaspoon oil in the cylinder and turned it over changed the oil and re-filled it.


Total cost= $500 at the most in 15 years for a 5000w no-name with a B&S engine and the receptacle and cord.

solar_dave

Re: How can I disconnect from utility in event of power grid melt down?

If you are worried about Armageddon then spent your money on Smith and Wesson. If it is a few day outage problem get a generator, store and rotate some gas or used LP/Nat Gas.

In the end of the world scenario the likely hood of staying put is pretty slim, use up your local resources like perishable food and get ready to move to someplace more sustainable. Stock pile canned and dry items. Balance staying put with using up possible fuel for a move.

Personally I am looking at using the 2 Chevy Volts as a temp generator for the short term outage scenario by wiring up a TSW inverter to the 100 amp accessory fuse and saving the small truck for the end of the world deal. I think I can make a Volt last about a week on a tank of 9 gallons of gas just keeping the fridge and freezer running with some small loads like radio or small TV.

solarvic

Re: How can I disconnect from utility in event of power grid melt down?

Bill. I think with the gasoline now having alchohol in it I wouldn,t want to keep the gas over 3 or 4 months. Tell you why. My brother has his johnsereds chainsaw burn a piston. He traded it in on a new one and it burned a piston within a couple months. The company did replace the piston and cylynder ubder warranty but is blameing the gasoline for the meltdowns. I have a jonsereds chainsar that I used the gas left over from winter wood cutting in my huskvarna weed eater. It melted down too and the dealer blamed it on the gas. There are lots of sawmills in my area and there is a gas station about 10 miles from me that sells gas that he claims is alchohol free. A lot of the chainsaw users get thier gasoline there. Most high quality chainsaws run around 12,000 to 14,000 rpm. Don,t know if that is the reason the reason for the meltdowns. My huskvarna weed eater runs high rpm too. Maybe the little honda generators can take the low quality gas as they probably run lower RPm. :Dsolarvic:D

BB.

Re: How can I disconnect from utility in event of power grid melt down?

I am not happy with them putting in Alcohol either--And what they used before was MTBE, which was killing ground water wells with huge amounts of contamination by service station gas plumes (the MTBE acted like a solvent between the gasoline (which was just floating on the water table) to vastly expanding plumes of pollution).


The fuel stabilizer I use claims to work with alcohol fuel mixes too... I have been doing this for ~7 years now and fill my car/pickup with the fuel once a year for recycling and find it is working OK in the cars.

Propane is probably not a good thing here (large tank may be prohibited by code--not sure) and natural gas is not something that I would expect to survive an earthquake (although, so far, except for the places in SF and Oakland that actually had gas line failures are probably the only folks that lost natural gas service). Diesel would be interesting, but I have nothing else to recycle the diesel into so I now have another issue (again, plus the cost of double wall tank if I go with a bigger genset and tank).

If push comes to shove, I can use fresh gas from the car/pickup and only use the stored fuel in the genset when I run out.

I have been using the same fuel (5 gallon can with Stabilizer) for decades for my old push lawn mores without issue (B&S and Honda powered)... Not sure the genset is going to be that much different.

Don't have any great answers, and I hope I never have to find them out the hard way.

-Bill

Ralph Day

Re: How can I disconnect from utility in event of power grid melt down?

I seem to recall that premium gas has no methanol in it's formulation. I use it in any small engines, chainsaws, trimmers etc. My Husqvarna chainsaw manual calls for it's use, some others don't (Echo).

Ralph

Cariboocoot

Re: How can I disconnect from utility in event of power grid melt down?

As a general rule, do not use gasoline containing alcohol in any 2-stroke engine. Alcohol is a great solvent, and it ruins the lubricating ability of the gas/oil mix. Methanol is particularly dangerous for this, followed by ethanol, propanol, and lastly butanol (which can be used as a gasoline substitute in some cases). Most blended gasolines use ethanol. Bad news for 2-strokes.

solarix

Re: How can I disconnect from utility in event of power grid melt down?

I recommend a small battery backed system to complement your GT solar system. SMA has the Sunny Island system that can keep your GT inverter running but is maybe $7,500 installed. My solution is the Xantrex PowerHub 1800 system ($2000 incl. batteries and CC) that can keep your critical loads (fridge, lights, computer) alive during an outage. Connect it to your GT array either with a high-voltage charge controller ($1000) or rewire the array so that during an outage you can flip a switch and reroute a lower voltage to a regular charge controller to the PowerHub and keep it going indefinitely.

oil pan 4

Re: How can I disconnect from utility in event of power grid melt down?

skwright wrote: »

I don't want solar panels sitting on my roof and NOT be able to use them to power our house at least during the daylight hours.

Irony can be funny like that some times.
It helps to know what kind of system you have inside and out, this is one of the pitfalls to having them put together and installed by some one else.
You will likely need one of those gridtie/stand alone inverters. At this point it may be cheaper and a better idea to just have a stand alone inverter a few batteries with charge controler ready to stick in place of the inverter you already have after the power goes out. What takes out the power grid could fry your regular inverter so having a backup stand alone inverter isn't a bad idea.

Want to isolate your house from the power grid?
That is the easy part, its so easy any one can do it.
All you have to do is find your circuit box, open it and flip your main 100 amp circuit breakers off and you are now disconnected from the power grid.

tmarch

Re: How can I disconnect from utility in event of power grid melt down?

I also have a 6K system installed, and was thinking of this.
Going to check on a few panels and another inverter to back feed my current inveter and make it think the utility is up if the utility goes down.
From what my installer told me this will work and be up to code.
Now I do have a generator interface at my meter that allows me to run my generator without exporting any power to the grid.
Not unusual to have minor outages here and week or longer outages can happen.

waynefromnscanada

Re: How can I disconnect from utility in event of power grid melt down?

Since inverters intended for off grid use don't like having power reversed and forced back into their output circuits, I expect you'll very quickly see smoke coming from your proposed new inverter.

Cariboocoot

Re: How can I disconnect from utility in event of power grid melt down?

Getting power from grid-tie inverter systems when the grid is down by "fooling" them with a small off-grid inverter has been discussed on this forum numerous times.

In short form, it doesn't work.

Basically, there's no place for the power potential of the GT system to go except into loads, and if there aren't sufficient loads it will back-feed the OG inverter and charge the batteries. If there's not enough battery "load" to take the power ... the magic smoke comes out.

There are ways to get power without the grid, but it's not easy or cheap or as simple as "tricking" a big GT system with a little OG system.

erne

Re: How can I disconnect from utility in event of power grid melt down?

If you use knife type transfer switches in the panel system you can break your system down into useable sections that are wired to a normal off grid battery system. you need a controller, inverter and batteries. (not cheap) I have done a few of these for different people. the generator is a easier solution. if you go to the airport and by aviation gas you wont have the problem of alcohol and it will store for 6 years without any additives. (cost more though)

oil pan 4

Re: How can I disconnect from utility in event of power grid melt down?

erne wrote: »

if you go to the airport and by aviation gas you wont have the problem of alcohol and it will store for 6 years without any additives. (cost more though)

Or you can get a diesel generator.
This fall I finished off a barrel of diesel I had filled and left sitting since 2006. My truck ran great off that pre-ULSD fuel.

techntrek

Re: How can I disconnect from utility in event of power grid melt down?

erne wrote: »

if you go to the airport and by aviation gas you wont have the problem of alcohol and it will store for 6 years without any additives. (cost more though)

NO!

Sure, it has high octane so all of those volatiles will help maintain its shelf life for a long time, for use in non-high-octane engines like a generator. But there is one big problem with avgas...

LEAD

You try to run leaded fuel in an engine designed for unleaded fuel and eventually you'll have problems with the valves. Run it in a vehicle, one with a catalytic converter, and you'll fry the converter as its insides get coated with lead. Not to mention the lead is bad for the environment - the only reason it is still used for airplanes is it keeps the fuel stable at high altitude (prevents vapor lock).

Besides, it will be much cheaper to buy premium mogas (automobile gas), then add Stabil or Sea Foam to it. I just looked up 100LL avgas and the cheapest price around me was $5/gallon. Most airports were over $8.

Lee Dodge

Re: How can I disconnect from utility in event of power grid melt down?

techntrek said:
"You try to run leaded fuel in an engine designed for unleaded fuel and eventually you'll have problems with the valves." I believe this is not accurate. The reverse is true, and was a problem when unleaded fuels were first introduced. It was determined that the lead deposits had been acting like a dry lubricant on the valve seats, and without the lead in the gasoline, the valve seats showed excess wear, requiring redesign with harder seat materials. (Remember that graphite, a form of lead, is used as a lock lubricant.) Engines designed for unleaded fuel should not have valve problems when operated with leaded fuel.

Lead deposits will not "fry" a catalytic converter like the overheating due to a misfiring spark plug that will allow unburned fuel and air to enter the catalyst. However, lead will deposit in the converter and deactivate it, making it useless, but not due to overheating. As techntrek said, lead is certainly bad for the environment.

It is used in Avgas to achieve very high octane numbers; 100 octane is the standard high-octane aviation gasoline, while high-octane automotive fuels are typically around 93 ((R+M)/2). Since those engines do not have catalysts, there is not catalyst damage. Vapor lock has to do with the volatility (vapor pressure) of the gasoline and the fuel system design, and I don't think that there is any relationship to lead additives.

The lead could make deposits on the piston and head faster than unleaded fuels, but this would be a very long-term issue. To keep lead out of the environment, it seems like a better idea to use fuel stabilizers and occasionally refresh the gasoline by using it in a car, but NOT if it has lead in it since that would ruin the catalyst.

Lee Dodge

Re: How can I disconnect from utility in event of power grid melt down?

oil pan 4 wrote: »

Or you can get a diesel generator.
This fall I finished off a barrel of diesel I had filled and left sitting since 2006. My truck ran great off that pre-ULSD fuel.

Diesel fuel has different storage problems from gasoline, but it certainly has its own problems. Gasoline is much more volatile than diesel fuel (i.e., much higher vapor pressure), and gasoline can lose its light ends (most volatile components) during storage. It can also form gums. As the Army has found out, stored diesel fuel can grow biologicals, and they use an additive in their fuel to reduce this problem. I think the diesel fuel can also form gums. It is safer to store diesel fuel than gasoline, since the volatility is so low that leaked liquid fuel or vapor will not form a flammable mixture.

Hopefully your diesel truck did not have an oxidation catalyst on it when you ran your high sulfur content diesel fuel through it, as it will deactivate the oxidation catalyst or catalyzed particulate filter. Fuel filter plugging can be a problem when using old diesel fuels, so you might want to pour it through a filter on the way into the fuel tank on the truck.

vtmaps

Re: How can I disconnect from utility in event of power grid melt down?

Lee Dodge wrote: »

It was determined that the lead deposits had been acting like a dry lubricant on the valve seats, and without the lead in the gasoline, the valve seats showed excess wear, requiring redesign with harder seat materials. (Remember that graphite, a form of lead, is used as a lock lubricant.)

Graphite is NOT lead, it is a form of carbon. Perhaps the confusion comes from the so-called 'lead pencils' which may be graphite but certainly are NOT lead.
--vtMaps

oil pan 4

Re: How can I disconnect from utility in event of power grid melt down?

Lee Dodge wrote: »

Hopefully your diesel truck did not have an oxidation catalyst on it when you ran your high sulfur content diesel fuel through it, as it will deactivate the oxidation catalyst or catalyzed particulate filter. Fuel filter plugging can be a problem when using old diesel fuels, so you might want to pour it through a filter on the way into the fuel tank on the truck.

My diesel is a chevy 6.5 with a mix of later and earlier year parts. The 6.5L engine line ended long before DPF was even thought of.
I also added a fuel filtration system of my own design, it can take still hot used motor oil poured into its fuel tank and run fine.

From what I have been able to find the biologicals that get into diesel storage tanks live in water at the bottom of the tank and feed off diesel at the water oil boundry.
So no water, no problem.

oil pan 4

Re: How can I disconnect from utility in event of power grid melt down?

I have run 100LL AVGAS in my car plenty of times.
It still runs fine.

My car does not have a catalytic converter.

Lee Dodge

Re: How can I disconnect from utility in event of power grid melt down?

vtmaps wrote: »

Graphite is NOT lead, it is a form of carbon. Perhaps the confusion comes from the so-called 'lead pencils' which may be graphite but certainly are NOT lead.
--vtMaps

Yep, my bad. Lead is soft and malleable, so it is reasonable that lead deposits could help lubricate valve seats.