Setup an off grid while on grid.

Yogie · August 2014

Re: Setup an off grid while on grid.

Yes agree with all you said.

Some other issues to be factored in (as if there were not enough already).

When it rains the grid goes off. You know when you see rain coming or see forecasts of rain that the grid will be down a while. Sometimes 15 minutes, sometimes 2 hours, sometimes half a day, sometimes all day, sometimes for 3 days...... the worst i saw was 3 weeks !!!

So rain comes from clouds. When its cloudy there is less solar to go with an grid outage. So when the grid is down from rain there will be little if any solar going on.

So cant get away from the generator.

I agree that separate systems makes sense. - in some ways. But if the big genset is running then all systems should be on the big genset so as to load it up and make it work hard thus efficiently.

What do you mean by "using the grid as an "opportunity" load source" Do you mean design the system so that it runs on solar/battery/generator and use the grid as a nice bonus now and then?

Cariboocoot · August 2014

Re: Setup an off grid while on grid.

Yogie wrote: »

What do you mean by "using the grid as an "opportunity" load source" Do you mean design the system so that it runs on solar/battery/generator and use the grid as a nice bonus now and then?

Yes exactly that. Just leave it to power up when it's there and don't try to depend on it. You'd need alternate charging such as the big gen because as you said when it rains the grid goes down and the panels won't work! Loading the gen up as much as possible will make it more efficient for sure.

This is looking like a system that should use the now discontinued Xantrex XW with its two AC inputs (which most units don't have), but there's way around that as well.

I'd design for critical load systems first, optional power on its own. That would probably mean one for each of those 2kW air pumps, one for the 15kW water pump (most expensive; needs a lot of research to see if you can reduce that demand somehow or else settle for using the gen only here - it could perhaps also supplement charging when pumping), and one for refrigeration/other life essentials. Perhaps a fifth system for casual use items? Or possibly 'borrow' some power from the others when it's available for that. I mean this is going to be majorly expensive as it is.

KenZ71 · August 2014

Re: Setup an off grid while on grid.

Very interesting discussion.

For the air tanks would a pressurized storage system make sense? That is when the grid is available "store" compressed air for use later.

What about wind power to complement solar and / or genset?

mike95490 · August 2014

Re: Setup an off grid while on grid.

I've got +300 fruit trees i water in the summer, but since today is cloudy, I had to shut off the pump. I have enough storage to go 2 more days before I have to pump up the hill to fill the tanks. Generally, I only pump 2-3 hours a day, and then there is enough sun to recharge the batteries with the remaining sun hours.

So, any energy conservation you can do, will be the cheapest step, watts you don't have to generate are the cheapest. Compressed air storage instead of batteries to run airstones all night. Can you pump water over a "bumpy" aerating trough to get air into it ? Just keep breeding tanks running, and let the other tanks "flywheel" overnight ?

With this being a "critical" application, you need hot spare inverters and generators. Lots of fuel storage. What about super sizing the tanks, to the size of a large swimming pool - less population density, more "forgiving". When you have a week of cloudy weather, it's all generator time, the PV does not give anything useable (<10% of nameplate).

Yogie · August 2014

Re: Setup an off grid while on grid.

Cariboocoot wrote: »

I mean this is going to be majorly expensive as it is.

Yeah it is. I'm braced for it. Not much i can do about it -i mean I'd prefer not to be sinking that kind of money into it, but it is what it is. If i want to make life bearable and things to actually work i have to build my own power system. The more i think about it the more i think that you are right - use the grid as much as possible when its there, but design for it not being there. When i have grid, i got off on the cheap that day. Even in the rainy season we generally get power back a few hours after a major down pour. But then we can get rain that goes the whole day and night without let up some days. The rain is 5 months of the year. But seriously, as soon as it sprinkles, the grid goes down.

My first thought on all this was to put in a lot of battery and use the grid and a big genset to charge it, but the more i look the more i see how little you actually get out of batteries.

The big pump is a must - i have to flush tanks for at least 6 hours a day. Full scale operation calls for 65 cubes per hour. 10 hours a day would be better. This is a massive amount of water. 15Kw 3 phase is a LOT of energy. I know i'll only ever run that on big gen or Grid. I need to do a deep dive into VFD pumps as i know zero about them. Not sure where that may lead or how it could help at this stage, but sounds interesting.

The 2Kw blowers are essential. This is to operate air driven filters. Filters are a living thing. More then an hour without water being pulled across the bacteria bed and the filter dies off. The idea of the filter is to keep water parameters good while there is no fresh river water flushing through the tanks. I have also thought about how else i could do this. I also thought about the idea of running a compressor to fill compressed air bank and slowly bleed that into the filters but this gets into a whole other area of knowledge (and danger).

Lifestyle is important. I've already spent too many years living rough out here. I've lived off ice blocks to keep things cold for years. Tired of this. I just got a TV and a satellite decoder - living it up now. Had the Hi-fi since forever - cant manage without music. Lights at night when the grid goes down and its pouring rain and lightening is cracking everywhere will be comforting. Got a freezer now and adding a refrigerator. Getting all fancy modern now (got a wife to take back there now so have to get civilized). Its 420 Kilometers to go to the shops so the freezer is important - such a drag to leave before the sun comes up and get home in darkness just to go shopping. Would very much like to keep fresh meat - that is, cow meat like T-bone and rump, pork chops, bacon etc.

So yes a lifestyle system makes sense. This is where i wonder if a 2000 amp/hr LifePo battery makes sense. Could use the battery for the lifesty;le items and the blowers - when the grid is down it could let us run the blowers for 2 or 3 hours on battery then fire up a smaller genset and run for 3 or 4 hours to charge battery and run the blowers then turn off for 2 or 3 hours and run on the batteries again - keep this cycle up. It cuts generator run time in half.

I def need to stack inverters for redundancy. In fact my policy is a min of 2 of everything. I get a headach when i think of the bottom line cost on all this.

Keeping a wife is expensive!

Yogie · August 2014

Re: Setup an off grid while on grid.

KenZ71 wrote: »

What about wind power to complement solar and / or genset?

Thought about air tanks but this would be pressurized and it scares the bejesus out of me to have high pressure air vessels around. Plus its a whole trade/industry in its own right which i know little about. Well OK i dont much about off grid power systems either...........

Yes we have wind. Pretty steady during the rainy season actually.....hmmmm there's a thought !!!! I looked at wind but everything i read said forget it. We get two major wind patterns per year. One wind pattern blows from the NorthEast to the South West. Starts in October and blows through untill about March/April. Starts about 9-10 in the morning and dies off around 16-17 in the afternoon. Gets to a pretty stiff breeze through the day. Hmmmmmmm. Could this be something to look at to fill in the holes when the grid is down and its pouring rain and thus overcast? Rainy season is from December to end of April.

Have to think about this.

Cariboocoot · August 2014

Re: Setup an off grid while on grid.

Wind:
Better than 10 mph average speeds?
Can you get a tower for the turbine at least 50 feet up?
What about lightning seeing it as an attractive path to ground?
Will the air speed reach hurricane force and damage things?
Can you afford a good brand like Bergey instead of some El Cheapo which won't come close to its rated power?
Is there enough over-all wind potential to make it worth the investment?

Put an anemometer up and find out first.

Yogie · August 2014

Re: Setup an off grid while on grid.

mike95490 wrote: »

With this being a "critical" application, you need hot spare inverters and generators. Lots of fuel storage. What about super sizing the tanks, to the size of a large swimming pool - less population density, more "forgiving". When you have a week of cloudy weather, it's all generator time, the PV does not give anything useable (<10% of nameplate).

yes a number of inverters - i was thinking of "Stacking" them to get more capacity and some redundancy. Also i believe inverters only last a max of 10 years and have to be replaced - so almost a consumable item?

Yes lots of fuel storage. Already thinking of this as theft is a MAJOR issue. Tanks are already super sized - hence needing 65 cuber per hour. Yes less densely stocked tanks is a major area to be on top of - its a balancing act.

Yep - in the rainy season when the grid is at its MOST FLAKY i have heavy cloud cover so little solar. But as i just realised, there is **WIND** all day 27 days out of 30 per month (guessing here but its most days - its a rare day in the wind season not to have a windy day). Its pretty steady and regular. I need to look into this again. Turbines were stupid expensive for what you get from them.

Yogie · August 2014

Re: Setup an off grid while on grid.

Cariboocoot wrote: »

Wind:
Better than 10 mph average speeds?
Can you get a tower for the turbine at least 50 feet up?
What about lightning seeing it as an attractive path to ground?
Will the air speed reach hurricane force and damage things?
Can you afford a good brand like Bergey instead of some El Cheapo which won't come close to its rated power?
Is there enough over-all wind potential to make it worth the investment?

Put an anemometer up and find out first.

Better than 10 mph average speeds? -> Not sure how to estimate it but it is a pretty steady wind all day - starts around 10am early in the season and cuts out around 4 in the afternoon, then as the months go on it starts earlier every day and cuts out later each afternoon until its over - then we have a month to 6 weeks with no wind then we get a trade wind from the other direction that blows for about 2 to 3 months. But this wind is a killer. It howls - usually starts early in the morning and keeps going till mid day then dies off - some days it goes all day - its a very uncomfortable wind - we all hate it. But its certainly there.

Can you get a tower for the turbine at least 50 feet up? ->> Yes no problem. But a tower is expensive. But in principle yes we can do that.

What about lightning seeing it as an attractive path to ground? ->> Major issue !!!!

Will the air speed reach hurricane force and damage things? - >> Not THAT big an issue but we do have our days when this can happen. Usually between Xmas and new year. Once we get through that period no more risk of such until next year.

Can you afford a good brand like Bergey instead of some El Cheapo which won't come close to its rated power? ->> Yes i could if i had too. Prefer not too of course but if this actually worked then yes its doable.

Is there enough over-all wind potential to make it worth the investment? ->> Not sure. I think so though. Its pretty steady in the various seasons. I can try to dig up records from UN as they did a biodiversity study on this area and i am sure it would all be there. You know how the pointy heads like to measure everything :-)

Put an anemometer up and find out first. ->> Yes this is the way to go,......AND the wind starts in about a month or so.

Yogie · August 2014

Re: Setup an off grid while on grid.

As i thought......... the pointy heads have had a field day......

"Abstract

Diel changes in wind speed, wind components, and evaporation at Lake Tanganyika were analyzed with several automatic sampling stations around the lake and meteorological buoys on the lake with high sampling frequency. Evaporation was calculated with aerodynamic and energy balance methods for the south and north ends of the lake. Winds of thermal origin blew from the lake during the day and land winds occurred at night. The onshore-offshore air temperature gradient during the day was highest, and winds were generally strongest, in the dry season. High evaporation was associated with south winds because wind speed at both ends of the lake was generally highest from the south, in part due to the southeast trade winds during the dry season. Evaporation was, therefore, influenced by the diel pattern of land and lake winds, highest at night in the south and highest during the day in the north. The annual evaporation rates increased by 43% from north to south. Mean lake wide evaporation was 1,821 mm/yr (range 1,536 to 2,022 mm/yr determined with three techniques), 120 mm more than previously estimated. Nocturnal mixing in the south is more dependent on wind forcing and evaporation while heat loss from the surface by sensible heat transfer and outgoing longwave radiation plays a more important role at the north end of the lake."

The strong wind they talk about in the dry season is the one that i mentioned that blows from the South East and is a killer wind. It blows in May, June and July then goes away. August is quiet and a little puff of wind starts up from the North East every day in September until October by which time its getting to be a fair wind all day.

Hmm could this possibly be the answer? Rather then panels, a turbine? Who would of thought !

http://gleon.org/sites/default/files/pdf/meetings/G9_presentations/G9_Pres-OReilly.pdf

So, wind speeds decreasing as global warming increases. Wind speeds decreased on El Nino years. Its all there.

Then this......

"In their analysis of Lake Tanganyika's ecosystem1, O'Reilly et al. claim that climate change, in the form of rising temperatures and falling winds, is causing a decline in the lake's productivity. However, their own data show that air temperatures were either steady or dropped slightly between 1952 and 1978, rising only slightly between 1980 and 1992, and that wind speeds have increased by 35% since 1985. These climate changes therefore have no correlation with either lake temperature or productivity, so it cannot be inferred from their data that climate change is the cause of the productivity decline."

So contradictory.

Need to do my own wind sampling.

Cariboocoot · August 2014

Re: Setup an off grid while on grid.

Yogie wrote: »

Need to do my own wind sampling.

Bingo.
Those numbers will be the only ones that matter.

mike95490 · August 2014

Re: Setup an off grid while on grid.

You need to be looking at the large, commercial 50KW wind turbines, like they use on wind farms, not 1KW homeowner turbines. Ouch, that's going to cost you.

Batteries. OMG. How about trying a couple forklift banks, before you spend $$ on Li banks ? Actually measure usage for a couple years. You might have to pay the battery company to drive a heavy truck out to your place, and need some tool/machine to unload the batteries and move them into position. But way cheaper to learn on them instead of Li*

And look into the VFD drives, you may be able to cut your power in half, with only a tiny reduction of material handling, by setting according to conditions, and not just hanging a way big motor on the gear-shaft.

CDN_VT · August 2014

Re: Setup an off grid while on grid.

Why not use wind to pump air & water ?? Like this :
http://t3.gstatic.com/images?q=tbn:ANd9GcSDLByH4dkOfeaYIWb_SnAqDdGCN8oFRdHrq5phuqtGY8WJKLbN0Q

Been done like this in NA since the 20's . And still to date , takes a huge load off the power required & can run all day if there's a breeze. They are built to self limit in storms .. I lived with one as a kid.

VT

Sorry I couldn't post a pix of a water pump wind mill .

BB. · August 2014

Re: Setup an off grid while on grid.

Not to scare you--But large/3 phase generators+motors and off grid solar power systems are a whole new level of "heck":

Is the system set up right

And sometimes, you just have to get a different engineer to find/fix the problems.

-Bill

Yogie · August 2014

Re: Setup an off grid while on grid.

mike95490 wrote: »

You need to be looking at the large, commercial 50KW wind turbines, like they use on wind farms, not 1KW homeowner turbines. Ouch, that's going to cost you.

Yes. I looked at turbines but very quickly moved on as it seemed to be a non starter. I'd really need to measure the wind speeds to know for sure whats going on. Wind seemed over expensive and maintenance intensive for what you get out of it. So i thought solar and batteries made more sense given we do have grid - 50% of the time.

mike95490 wrote: »

How about trying a couple forklift banks, before you spend $$ on Li banks ?

My first thought was Flooded lead acid. But i do have some unique challenges that LiFePo solves. I can only afford to to do this once. I cant afford to put in FLA only to ruin them in short order because that is what will happen. The single biggest issue is the bank being discharged a bit and not recharged while i am 1500 Klms away on the other side of the country and then trying to get my guys to get the bank charged back up correctly. With LiFePo that concern goes away. Another reason LiFePo works for me is given the split up of systems as suggested (which i think is the way to go) i can power the 2Kw motors and lifestyle stuff on battery for a few hours then when cycled down to say, 30% DOD, start the generator to take the loads and charge the batteries back up to 90% SOC. Once back to 90%SOC (have i got the terms SOC and DOD right?), the genset goes off andload transfers to battery for 3 or 4 hours, then back to genset. This halves the genset run time which saves $$$ in fuel. This savings, pays for the LiFePo price premium. If all the talk about the LiFePo is correct i could get 3000 cycles out of them at 30% DOD. Maybe more. No one seems to have a definitive answer on this though from what i have read. The concern about them seems to be longevity - its just not known i think. If i use them as described i will get my 3000 cycles before the calender time is expired, so this seems to be the right way to use them. please correct me if i have misunderstood this concept.

Agree on the VFD drives - i know zero about them so need to take a long look to see how this could help us. The reason i have the pump set i do is to move 65 Cubes per hour up a 13m high hill, 90 meters from the water through 110mm O.D pipe. The head losses were calculated for the volume needed. I am actually a little under the amount of water i need but we will rotate water around, so we are already in a position where we have tried to reduce inputs as much as possible.

\

stephendv · August 2014

Re: Setup an off grid while on grid.

Yogie wrote: »

Water pump - 15Kw motor 3 phase - need this for about 4 hours per day

Since it doesn't matter when the water is pumped, it would be easier on any system you install if this were an 8kW pump that ran for 8 hours, rather than 15kW for 4 hours. Easier on the batteries and you wouldn't need such a monster genset. Your peak loads would then be something like: 8kW + 2 x 2kW + house loads (2kW?) = 14kW.
If you wanted to keep your 3 phase power you'd need to distribute the loads more or less evenly across the phases, so could be done with 3 x 6kW inverters (which obviously must support being paralleled in 3phase).

mike95490 · August 2014

Re: Setup an off grid while on grid.

I can only afford to to do this once. I cant afford to put in FLA only to ruin them in short order because that is what will happen. The single biggest issue is the bank being discharged a bit and not recharged while i am 1500 Klms away on the other side of the country and then trying to get my guys to get the bank charged back up correctly. With LiFePo that concern goes away.

This is, in my mind, EXACTLY why you use a sacrificial set of batteries, better Lead acid, than Li. Until you nail down your power profile and needs, you stand a good chance of, through neglect or ignorance, destroying the first set of batteries. Read some of the Li threads about cell balancing and upper / lower voltage limits, and the consequences of a fast charge on a depleted Li bank.

If there was an installed system, just like yours, or 90% that same, then you can carry over a lot of assumptions. But you are on new ground with this, and will be making "discoveries" along the way.

BB. · August 2014

Re: Setup an off grid while on grid.

Regarding pumps, there are lots of options available--A pump that is designed to have positive pressure on the inlet (submerged, in a pit below water level) can be something like 20% more efficient (SWAG--I don't remember the details). And a PM Motor (permanent magnet motor) can also be something like 20% more efficient.

And if you use a VFD and can vary the pump RPM based on need (vs just running the pump at 100% RPM with excess water flow or a bypass/blocking restriction), you can save a lot of energy there too (i.e., run at 1/4 pour for much of the year and/or when grid is down, and run at "full power" for spawning/flushing filters/etc.--Based on your needs).

Getting a wide option of pumps and motors may not be easy in central Africa--But VFD's are becoming pretty common and are shipping around the world.

There are now (at least from China) VFD's that can connect directly to the solar array (single DC input, 3 phase variable frequency output). One of the links I give you, I believe the poster used a "standard" VFD and simply dropped the DC power past the AC input stage (or even fed DC through the AC stage--That is possible in some/many/few??? designs).

You probably don't want to deal with batteries on big pumping systems systems (at least at "full power")--It is expensive to maintain and somewhat inefficient (every voltage/power conversion is another 5-15% loss)... Since you can take the power cut (minutes to fire up the generator)--You can do some simple cost benefit comparisons:

Installation costs + solar panels + new batteries every X years + inverters + chargers every ~10+ years + interest + etc.) / (20 years of kWH energy "used") = battery power costs
Installation cost for genset + maintenance + 20 years of fuel / 20 years of kWH of power used = generator power costs.

Of course, you can trade out solar panel costs by using Grid + Generator power to recharge the banks between outages.

What will work out best for you--I really don't know.

-Bill

Raj174 · September 2014

Re: Setup an off grid while on grid.

Hi Yogie,
I recently found a good source for LiFePO4 batteries. Good prices also. They sell large banks around 48 volt 800 ah. They also custom build upon request. I believe their built in battery management will allow charging as if they were lead acid but I would speak to them about that. They are in Utah, but ship world wide. Here is their web site. Look it over and give them a call. http://www.electriccarpartscompany.com/Custom-Built--Special-Order--Lithium-Rechargable-Batteries_c_10.html
Good luck,
Rick

Yogie · September 2014

Re: Setup an off grid while on grid.

So this seems so unrealistic.

I went to visit some friends down country. They farm several thousand hectors of land. Turns out they run a 90Kw pump to pump from a river to the wheat fields they irrigate. While there they received a power bill from the power company. They consumed 30,000 KwHrs last month - cost = $850. !! Works out to about 3.2 to 3.4 cents per KWHr. This is agricultural rate - same as i qualify for. They have the same issues i do and also complain bitterly about the power situation. But 3.2ish US cents per KWHr ?? makes any other form of power so incredibly expensive. If only the power company could get its act together !

We also had long discussions about VFD pumps. My friend Rodger has tried VFD pumps but says they are not suitable for our grid as the frequency drifts all over the place and that this has some sort of detrimental effect on VFD controllers. Result is he has blown a number of VFD controllers. He says the only thing that works is a "soft starter" which is half way between a Star Delta starter and a VFD starter.

Also i saw the maximum demand charge on the bill - it was 36Kva and he runs a 90Kw pump. He says since he installed the soft starter the maximum demand charge has gone way down. I dont understand this.

This is so terribly complicated.

BB. · September 2014

Re: Setup an off grid while on grid.

Yogie wrote: »

So this seems so unrealistic.

I went to visit some friends down country. They farm several thousand hectors of land. Turns out they run a 90Kw pump to pump from a river to the wheat fields they irrigate. While there they received a power bill from the power company. They consumed 30,000 KwHrs last month - cost = $850. !! Works out to about 3.2 to 3.4 cents per KWHr. This is agricultural rate - same as i qualify for. They have the same issues i do and also complain bitterly about the power situation. But 3.2ish US cents per KWHr ?? makes any other form of power so incredibly expensive. If only the power company could get its act together !

Yep--Power companies are Ogers... Until you look at the bill for Ag/Large industrial users.

We also had long discussions about VFD pumps. My friend Rodger has tried VFD pumps but says they are not suitable for our grid as the frequency drifts all over the place and that this has some sort of detrimental effect on VFD controllers. Result is he has blown a number of VFD controllers. He says the only thing that works is a "soft starter" which is half way between a Star Delta starter and a VFD starter.

VFD's are not the end all yet--I think many VFD's have MSW (modified square wave outputs)--Which can be hard on motors.

Also i saw the maximum demand charge on the bill - it was 36Kva and he runs a 90Kw pump. He says since he installed the soft starter the maximum demand charge has gone way down. I dont understand this.

Industrial users may have "demand charges"--Basically the peak load in a 15 minute period (per month or last 12 months). Also known as a reservation charge--You pay for the right to pull X amount of power.

Also, there are different ways of billing for power. A residence typically pays for "kWH" (k Watt*Hours). We are bill for actual energy used.

However, when running large motors and other equipment, the current and voltage are not always in phase. For motors, it is easy for the current lag (power factor) to be in the range of 0.6 to 0.8 Power Factor (PF). Basically, the utility has to supply more current to make up for the poor power factor (think if peddling a bicycle--And instead of peddling "in phase" with the peddles on trike/non-coaster type bike--You "back peddle" during part of the rotation of the peddles--More or less, to keep the constant amount of power, you have to peddle "harder" on at the right time to make up for back peddling at other times).

So, the utility may charge for peak kVA (volt*amps) or pay for poor PF... Basically 1/0.8 or 1/0.6 * more on your kWH power bill.

It sounds like your friend's 90 kW pump is running at much less than rated load. That can save money (less heating losses running at lower loads), but also cost money (typically unloaded motors have worse power factor).

You can "fix" poor power factor with motors by adding capacitors (inductors lag current, capacitors cause leading current; Add the two together and you get near 0.95 Power factor--A good thing). While adding capacitors is a "good fix" for power power factor--There are some very series engineering rules that cannot be violated or some very strange/dangerous things may happen. Also, the PFC (power factor correction capacitors) need to be switched--Otherwise, the poor -0.6 PF becomes poor +0.6 PF -- Which can still cause excessive kVA charges.

For people/companies with large power bills--Sometimes hiring a Power Engineer or talking with a local pump/equipment dealer can improve the electrical efficiency of the installation--And save some $$$ on the power bill.

-Bill

solarix · September 2014

Re: Setup an off grid while on grid.

Hate to say this a solar guy, but maybe talk to the power company and see if they have a solution - with the money you are proposing to spend on your own system maybe they can give you preferential treatment or something if you pay double rates or more? Or is money spent on the authorities just a waste?

KenZ71 · September 2014

Re: Setup an off grid while on grid.

It seems reasonable that at least a few jobs will be created with this effort. Any chance you can get help with planning, funding, security, etc from ______?

Would either your suppliers or clients have support suggestions?

Maybe a local community group? Or even solicit help from a charity group that wants to partner with someone & create jobs. A few friends here in the US travel to Haiti and / or central America to help build schools, solar panels on farms, etc.

Setup an off grid while on grid.

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