Considering converting a gridtie system in NY to a hybrid/off-grid system, among other options

srk9 · December 2016

My current home in NYS has a gridtie solar system with some surge protection:

1. 30x Sunpower E20-327 panels each with a Solaredge optimizer
2. A SolarEdge SE10000A-US-U Inverter
3. A 200 amp panel, plus a small 80 amp subpanel for the solaredge, plus another load.
4. An Eaton CHSPT2ULTRA SPD2 surge protector (misinstalled on a 15 amp breaker by the electrician)
5. A Leviton 50240-MSA surge protector at the electrical meter
6. A Cyberpower 1350VA UPS for my home network gear equipment (with the fiber ONT in-doors, although the ground wire is questionably attached to an outlet)

I have the following goals in order of importance:

1. I want my internet connection and VoIP phone to work at all times.
2. I want to ensure that my house is protected against indirect lightning strikes and dirty electricity
3. I want to make certain that a recurrence of Hurricane Sandy, where we were without any power for 2 weeks, is impossible at any time during the year.
4. I want to stay in budget.
5. I want to minimize recurring costs from equipment failures or wear out / maximize reliability
6. I want a high level of energy efficiency. (e.g. a double conversion UPS that filters power from a generator would be only okay if the ~87% efficiency in double conversion mode is amortized by running in line interactive mode for 99% efficiency when the generator is not running)

Some ideas on my mind are:

1. A dedicated off-grid microgrid for the network. This would just be some additional panels, a small battery and a charge controller. No inverter is needed because I am modifying equipment so that the entire network runs off 48VDC. I could probably shoot for 12VDC if it were more practical though. I am already experimenting with different equipment with the goal of getting power consumption down to maximize the runtime of the existing UPS. I expect that will make it easier to power it off a small micro-grid.
2. A diesel generator powered by #2 home heating oil from the home heating oil tank, a transfer switch and a split-phase hybrid double conversion UPS for the entire house, with the solar panels on the grid side of the transfer switch (such that no generation occurs when the power goes out).
3. An AC coupled inverter + a large battery so that loss of grid power does not result in an outage. This avoids violating the solar contractor's warranty.
4. Replacing the Solar Edge inverter with something compatible with the optimizers while getting a compatible charge controller for a large battery.
5. Doing some combination of the above for added reliability. e.g. #1 + any of #2, #3 or #4. Perhaps even #1 + #2 + either #3 or #4.

Some of the problems with these ideas are:

1. It is incredibly hard to get good electrochemical cells / a good battery in NY, especially if I don't want to spend a small fortune. Tesla's stuff definitely isn't available and it is hard to find suppliers for nickel batteries that charge less than Iron Edison, which appears to be overpriced.
2. It is incredibly hard to find information on charge controllers.
3. It is incredibly hard to find information on reliable diesel generators or how to connect a home heating oil tank to one without replacing the oil heat.
4. It is incredibly hard to find an efficient UPS capable of doing split-phase operation for 200 amp electric service.
5. I have different cost sensitivities for each of these options. If I do #1, I would want to do it for $500. If I do #2, I would want to spend up to $10,000. If I do #3 or #4, I would only want to spend as much as $25,000. If I, for example, were to do, #1, #2 and #3, I would be willing to spend $500 + $10000 + $25000 = $35500.

I am new to the idea of becoming independent from the electrical grid. I have had plenty of trouble finding people experienced with these things to advise me. The solar contractors here are only interested in building the same gridtie systems everywhere and don't care if you want a hybrid system. I had some really bad advice on it from my contractor who could have sold me an even larger system had he just listened to my demand that the system should be energy positive on every day of the year. Instead, he ignored my requirements and told me that winter generation is half summer. That made me think I could cut back on usage to make a battery work during an extended fall/winter power outage when it was eventually installed. I later learned after the system was that my attempts to improve energy efficiency are insufficient to achieve even that much because winter production is more like 1/4 of summer production, rather than 1/2 as they claimed.

Ultimately, I want the ability to flip a switch and then ask the electric company to disconnect us should their talk of worsening the benefits of net-metering policy like other electric companies are doing in other states, in addition to being insulated from electrical grid outages. Whether I gain that ability that in the short term is an open question, but if I could achieve my goals today, I'd jump on it, even at a price of $35500.

Would someone advise me?

Photowhit · December 2016

I think I worked out that to provide an equal amount of used energy off grid compared to a grid tied system would require 3 times the array size with good solar isolation or 4 times or a generator in poor areas. No time to hunt it all up right now, needless to say if you have a 10Kw array you will need a huge battery bank, multiple charge controllers (about 1 per 4500 watts of array in a 48 volt system) and huge/multiple inverters.

srk9 · December 2016

I guess the battery bank is out for now then, but having a diesel generator seems feasible. I just need a way to pump fuel to a day tank from the home heating oil tank, a transfer switch and a reliable model that generates a clean signal (or runs it through something that does). Doing that would probably enable me to meet my goal of keeping the network up at all times if I leave the UPS in place.

Any suggestions on how that could be done with a typical 275 gallon heating oil tank?

cupcake · December 2016

Just STAY ON THE GRID! Your loads are simpy too much to practically do off-grid, UNLESS you want this overly-complex and expensive system.. What's the point if you are already grid connected... what's a Kwh there? 10 cents? Less? Just stay on-grid... I've lived off grid for years, the KEY is to 1) Size your system to the WINTER SUN and 2) Reduce/eliminate your loads as much as possible (ie LIFESTYLE CHANGE)

If you want to use tons of electricity and you are on the grid, it makes no sense to go off of it... winter sun IS ~50% of summer sun, more or less depending on your location.. $35,000 to live off the grid? Lol, I must have spent $2,500... it's all about balance, if you can't do that, then ON the GRID is where you will do best...

animatt · December 2016

Ac coupling seems like a okay solution to weather power outages.
I guess it depends on usage. But I would think something like a magnum pae4448 with something like 400 ah of golf cart batteries.
I would think this could be setup for maybe $3500 usd.
Would be inverter, control panel and batteries.
I would think it a robust system for backup.

For a little extra you would rewire breaker panels and run all important loads off the inverter.
I would not worry about going fully offgrid.

mike95490 · December 2016

Get a UPS for your internet router. $80 good for a couple hours

. I want to make certain that a recurrence of Hurricane Sandy, where we were without any power for 2 weeks, is impossible at any time during the year.

Same Hurricane that blew your neighbors lawn chairs into your solar array ?

200A service

That would take 4 of my 6Kw inverters to be able to supply that. Could you cut back a bit and manage on 12Kw in an emergency?

diesel generator powered by #2 home heating oil from the home heating oil tank

If you use heating oil, JP2, or kerosene, you have to add lubricity to the fuel, or the pump and injectors WILL Seize. Maybe not in the first hour, but they will. 200:1 Fuel:2stroke oil, will do the trick. Also heard ATF is a good lube for injectors but have not tried it. My gensets fuel pump really sounds bad if there is no lube in the fuel (today's low sulfur fuel is not what the 1930's engine was designed for.

It is incredibly hard to find information on reliable diesel generators or how to connect a home heating oil tank to one

Just ask. What does industry do? Look for 1800RPM gensets, aim for 2x your intended load, the engine is fine, but I think the newer alternators are too wimpy, they can't handle any poor power factor.
Heating oil, look for older gear, with mechanical fuel pumps, <10,000 psi injectors, and mix oil onto the fuel for lubricity. Modern gear with >20,000 psi won't work with less than pristine diesel.

BB. · December 2016

As mentioned above--Solar power tends to be much more expensive overall vs standard (in town) utility power... Somewhere between 5-10x the cost (very roughly) by the time you take panels+electronics+battery bank (plus replacement every 5-10 years or so, losses of efficiency, genset maintenance+fuel, etc.).

Also, many communications paths are not battery backed up (cable TV, cell phone towers, fiber lines, and such)--Or have only a few hours of battery backup. Not like our old phone lines which had a week (or more?) of diesel fuel for running the phone exchange.

Regarding genset+heating fuel--One Canadian website suggests that using Diesel #2 for home heating+genset fuel can be very cost competitive:

http://www.powertogo.ca/diesevslheating.htm

If you want backup power--Diesel (or other fuel) can make sense for 1-2 weeks of off grid emergency power (if your neighbors can accept the noise and fumes--Plus if your allowed to install in your neighborhood). Backup solar power for weeks/months of backup power can work out--But you probably are looking at 100 kWH per month for a "cost effective backup system" that can keep you relatively comfortable (like 3.3 kWH per day--enough for LED lighting, a fridge, well pump, washing machine, laptop computer). You might even get under your $35,000 limit (without genset).

But you will not run 1,000+ kWH per month (30+ kWH per day) for that low of cost.

-Bill

animatt · December 2016

animatt said:

Ac coupling seems like a okay solution to weather power outages.
I guess it depends on usage. But I would think something like a magnum pae4448 with something like 400 ah of golf cart batteries.
I would think this could be setup for maybe $3500 usd.
Would be inverter, control panel and batteries.
I would think it a robust system for backup.

For a little extra you would rewire breaker panels and run all important loads off the inverter.
I would not worry about going fully offgrid.

I am not seeing where he mentions his loads anywhere I see he has a 200 amp service but that means very little. What are actual loads he would need/ want to support.

I could have missed it though.

Anyway something to add to my above quote. On further thought if you had said funds and we're going magnum ac coupled method. You would probably want to pickup the acld model. It goes between magnum inverter ac output and your gridtie solar setup. it allows one to regulate battery charging properly and automatically.

Also forgot about gridtie array sizing it can support. Your gridtie system is LARGE and would overpower a single magnum inverter. You would need a way to trim back your solar output so when you are running decouple from center electric grid you do not overheat the magnums internal transformer and other components.

That or made sure you were using extra power and not back feeding it to the inverter. Not sure if the acld model could thow on opportunity loads quickly enough or not.

Again above solution would not be about saving money. But assuming your solar panels were still working after a serious event would keep you going for a long time with proper management of electrical loads.

srk9 · December 2016

> @animatt said:
> animatt said:
>
>
> Ac coupling seems like a okay solution to weather power outages.
> I guess it depends on usage. But I would think something like a magnum pae4448 with something like 400 ah of golf cart batteries.
> I would think this could be setup for maybe $3500 usd.
> Would be inverter, control panel and batteries.
> I would think it a robust system for backup.
>
> For a little extra you would rewire breaker panels and run all important loads off the inverter.
> I would not worry about going fully offgrid.
>
>
>
>
>
>
> I am not seeing where he mentions his loads anywhere I see he has a 200 amp service but that means very little. What are actual loads he would need/ want to support.
>
> I could have missed it though.
>
>
> Anyway something to add to my above quote. On further thought if you had said funds and we're going magnum ac coupled method. You would probably want to pickup the acld model. It goes between magnum inverter ac output and your gridtie solar setup. it allows one to regulate battery charging properly and automatically.
>
> Also forgot about gridtie array sizing it can support. Your gridtie system is LARGE and would overpower a single magnum inverter. You would need a way to trim back your solar output so when you are running decouple from center electric grid you do not overheat the magnums internal transformer and other components.
>
> That or made sure you were using extra power and not back feeding it to the inverter. Not sure if the acld model could thow on opportunity loads quickly enough or not.
>
> Again above solution would not be about saving money. But assuming your solar panels were still working after a serious event would keep you going for a long time with proper management of electrical loads.

Excluding large loads at >=500 watt, the draw of the entire house is 500 watts or less. The large loads would be:

* The central AC at ~7000 watts
* The ventless dryer at ~500 watts (the heating element is never used)
* The microwave at ~1200 watts
* The range at like~ 2800 watts for the oven and maybe ~1200 watts for the stove.
* The oil burner for heat and hot water has been said to use ~500 watts, but it is hard to get good data.

If the heavy loads are not powered during an outage, I could probably get away with something like 2,500 watts of capacity during the day and 1000 watts at night at any point during the year.

As for the ALCD, I assume that you mean this:

https://www.solar-electric.com/magnum-energy-acld-40-load-diversion-controller.html

I do not have a place for the energy to go. I'd rather scale back production to match what the battery can handle in an outage rather than try to send the power somewhere.

srk9 · December 2016

> @mike95490 said:
> Get a UPS for your internet router. $80 good for a couple hours

I already have one, but I want it to run indefinitely during grid outages. A microgrid could ensure that. A generator could too. Right now, I have neither.

> . I want to make certain that a recurrence of Hurricane Sandy, where we
> were without any power for 2 weeks, is impossible at any time during
> the year.
>
> Same Hurricane that blew your neighbors lawn chairs into your solar array ?

My neighbors do not have lawn chairs and I am on a hill. The roof has never been damaged by a storm and I feel it safe to assume that the solar panels will never be damaged either.

> 200A service
>
> That would take 4 of my 6Kw inverters to be able to supply that. Could you cut back a bit and manage on 12Kw in an emergency?

12kW is probably more than the house uses at any given point during the year. I do not want to limit peak draw under normal circumstances, but I am okay with limiting it during an outage.

> diesel generator powered by #2 home heating oil from the home heating oil tank
>
> If you use heating oil, JP2, or kerosene, you have to add lubricity to the fuel, or the pump and injectors WILL Seize. Maybe not in the first hour, but they will. 200:1 Fuel:2stroke oil, will do the trick. Also heard ATF is a good lube for injectors but have not tried it. My gensets fuel pump really sounds bad if there is no lube in the fuel (today's low sulfur fuel is not what the 1930's engine was designed for.

I can check with the distributor to be certain, but I pay for #2 heating oil, which should be free of kerosene.

> It is incredibly hard to find information on reliable diesel generators or how to connect a home heating oil tank to one
>
> Just ask. What does industry do? Look for 1800RPM gensets, aim for 2x your intended load, the engine is fine, but I think the newer alternators are too wimpy, they can't handle any poor power factor.
> Heating oil, look for older gear, with mechanical fuel pumps, <10,000 psi injectors, and mix oil onto the fuel for lubricity. Modern gear with >20,000 psi won't work with less than pristine diesel.

Even if the diesel engine is mechanically sound, I have no idea how to get an alternator that outputs a good signal and is able to handle poor power factors should they happen. My only thought on how to handle a dirty signal would be to put every non-major load on a giant UPS unit like this one, although the power factor is another issue:

https://www.tripplite.com/smartonline-208-240-120v-16kva-11.2kw-double-conversion-ups-8u-rack-tower-extended-run-snmpwebcard-option-usb-db9-bypass-switch-nema-outlets~SU16000RT4U/

bill von novak · December 2016

I have the following goals in order of importance:

1. I want my internet connection and VoIP phone to work at all times.
2. I want to ensure that my house is protected against indirect lightning strikes and dirty electricity
3. I want to make certain that a recurrence of Hurricane Sandy, where we were without any power for 2 weeks, is impossible at any time during the year.
4. I want to stay in budget.
5. I want to minimize recurring costs from equipment failures or wear out / maximize reliability
6. I want a high level of energy efficiency. (e.g. a double conversion UPS that filters power from a generator would be only okay if the ~87% efficiency in double conversion mode is amortized by running in line interactive mode for 99% efficiency when the generator is not running)

Here's what I would do personally:
1) Get an inverter like an Outback VFX type. (Or if you can find a used Trace SW series out there, grab it - they are old, but are great inverters and have both a grid and a generator input.)

2) Get a small battery bank that can power your critical loads for a short time (1 hour?)

3) Get a small reliable generator like a Honda inverter type.

4) Put your critical loads on a separate panel; wire the output of the inverter to that panel.

Now set the inverter to float the batteries indefinitely. When power goes out, start the generator. When you run out of gas, you have an hour to get more.

animatt · December 2016

I am with bill but get an inverter that allows battery charging thru it ac output. [Backfeed]. This way you get the solar benefit as well. I talk about magnum inverters as I know they frequency shift it's output to drop the gridtie inverter when battery voltage rises. But that is the last line of defensive. And something like acld is the primary way. I am not sure how outback line of products work.

A simple dump load could be a water heating element. Or air heater elements. Basically resistive loads. You can get a 1000w electric space heater for a few dollars. Since it is an ac load you would not be running load off the offgrid inverter. But actually running it off the gridtie inverter. Because as a dump load you use it only when you have surplus power.

All the posters loads look very doable except the central air.
A 400ah battery at 48v would support a fair load. And with that huge solar array should work well.

bill von novak · December 2016

animatt said:

I am with bill but get an inverter that allows battery charging thru it ac output. [Backfeed]. This way you get the solar benefit as well.

What you are talking about is AC coupling. And that can work but is difficult to set up, balance and run - and will likely invalidate any warranty he has on the system.

It's also just not needed. Most places in the US don't see regular long blackouts, which is the only time such a system makes sense. And since bad weather often coincides with blackouts, you need the generator anyway for reliability. Why add the extra expense/complexity/risk for a use case you will almost surely never see?

If it's really important to this guy (say, he's worried about a Super Sandy or the zombie apocalypse or something) then he can buy an appropriate charge controller, connect it to the battery bank and just have it sit there. If the zombies attack then get up on the roof, rewire for an appropriate voltage and connect to the charge controller. (Run generator in the meantime.) You void your warranty at that point but presumably with the world ending (or power being out for a month) you have more pressing problems.

Considering converting a gridtie system in NY to a hybrid/off-grid system, among other options

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