Off-grid system for a restaurant

[Popeye]

Hi everyone,

First of all please excuse my english as it is not my native language.
I hope you will understand everything I write. I hope I understand everything I'll write haha.

I need some Help for an off-grid project.

This project is about powering a restaurant that cannot be reached by the grid.
At the moment, it is powered by a generator of 45 kVA. Very interested in a PV system because:

- when generator fails, the food in the fridges can rapidly be lost (thousands of dollars). It generally takes 1 to 2 days
to get it fixed. Waiting for a smaller back up gen.
- Cost of fuel
- Environnmental concerns
- Noise

The minimum I would like to achieve is to turn off the generator at night and run a battery bank instead,
or when the generator fails the battery bank takes the place of the gen.

Here are general datas I gathered:

- on a working day, the general consumption of the restaurant is 230 kWh average (opened from tuesday to saturday)
- While in service, the nominal power is 16 kVA and 20 kVA peak.
- Inactivity periods are of an average of 10 hours and the power needed at these moments is 5-6 kVA.
- Three phase electrical circuit

Please see graphic below. image_7151.png




15 to 20 kWp of solar panels can be installed on roof.
It looks like the power delivered by the Gen isn't constant enough so that it will damages the electrical devices in the long term.

I already have ideas in mind but I don't know if I can give brandnames of products here. If yes i will expose it.

So what are your thoughts about this project? possible? Impossible? Too expensive? ROI too long because of battery cost?
What do you reckon?
Any advice/idea is more than welcomed

I have some questions too:

- I wonder if an uninterruptible power supply can be used with PV power and gen at the same time.

If I can give more infos to help you guys answer please don't hesitate to ask me.

Thank you and best regards

Popeye

[DanKegel]

Hi!
Solar can cut your diesel bills, and possibly let you run during the day when generator is busted.
That might be worth it.
Turning off the generator at night will require energy storage... lots of it. That's the hard part.

Others can suggest battery systems. Another farther out option is using blocks of phase-change material in the fridges to keep them cool while the power is out; this might let you cut the generators at midnight, or get by with smaller batteries. The technique has been tried commercially in a few markets, eg India, where LG tried selling fridges called Powercut EverCool.
Good luck!

[Sunking]

- on a working day, the general consumption of the restaurant is 230 kWh average (opened from tuesday to saturday)

Sorry Popeye it will never work. First thing it would take is a large brand new building just to hold your $280,000 USD, 70,000 pounds of batteries you get to replace every few years.

Second point is there is nothing environmentally friendly about off-grid battery systems.

It would bankrupt you.

[solar pete]

Hi everyone,

First of all please excuse my english as it is not my native language.
I hope you will understand everything I write. I hope I understand everything I'll write haha.

I need some Help for an off-grid project.

This project is about powering a restaurant that cannot be reached by the grid.
At the moment, it is powered by a generator of 45 kVA. Very interested in a PV system because:

- when generator fails, the food in the fridges can rapidly be lost (thousands of dollars). It generally takes 1 to 2 days
to get it fixed. Waiting for a smaller back up gen.
- Cost of fuel
- Environnmental concerns
- Noise

The minimum I would like to achieve is to turn off the generator at night and run a battery bank instead,
or when the generator fails the battery bank takes the place of the gen.

Here are general datas I gathered:

- on a working day, the general consumption of the restaurant is 230 kWh average (opened from tuesday to saturday)
- While in service, the nominal power is 16 kVA and 20 kVA peak.
- Inactivity periods are of an average of 10 hours and the power needed at these moments is 5-6 kVA.
- Three phase electrical circuit

Please see graphic below. [ATTACH=CONFIG]n305757[/ATTACH]




15 to 20 kWp of solar panels can be installed on roof.
It looks like the power delivered by the Gen isn't constant enough so that it will damages the electrical devices in the long term.

I already have ideas in mind but I don't know if I can give brandnames of products here. If yes i will expose it.

So what are your thoughts about this project? possible? Impossible? Too expensive? ROI too long because of battery cost?
What do you reckon?
Any advice/idea is more than welcomed

I have some questions too:

- I wonder if an uninterruptible power supply can be used with PV power and gen at the same time.

If I can give more infos to help you guys answer please don't hesitate to ask me.

Thank you and best regards

Popeye

Hi Popeye and welcome to Solar Panel Talk, what you want to do may be achievable, however its going to be very expensive and will probably require a complete re think as to the way you currently use electricity. R U saying the property consumes 230kWh per day or is that 5 days worth Tuesday to Saturday??? What are the open hours of the restaurant ?? Does anyone live onsite when restaurant is closed, if so how many kWh does the property use then?

If your really only wanting to run off batteries at night while the guests are there you will need to do a loads analysis of the night time draw, you will need a kilowatt meter.

At the end of the day it sounds like you will need a system like in the link below, a complicating factor is running 3 phase equipment its doable but its going to cost you big $$$

https://www.solarpaneltalk.com/forum/solar-panels-for-home/solar-panels-for-homes-with-solar-batteries/20101-30kw-hybrid-solar-pv-system-in-australia/page2

Good luck you will need it.

[Mike90250]

Sadly, solar is not a cure for this much power. It could help, but it would cost a lot, and still need generators.

My suggestion is to get 2 efficient generators, and alternate running them on alternate days, But that is still a lot of fuel and oil changes ! You can look into upgrading appliances to more efficient ones, but that also has a large up-front cost.

[DanKegel]

Yeah... solar can cut fuel consumption (see e.g. http://cdn.intechopen.com/pdfs/12530.pdf ), but you can't shut the generators off at night without one of two big things:

a) a crazy number of batteries -- so expensive it wouldn't be worth it, or

b) big increases in the efficiency of your refrigerators -- which could take lots of time, effort, and/or money but might pay off in the end.

Option b) has the advantage that, if you take sensible incremental steps, you end up with lower fuel bills instead of a wasted fortune in dead batteries.

[Sunking]

Yeah... solar can cut fuel consumption (see e.g. http://cdn.intechopen.com/pdfs/12530.pdf ), but you can't shut the generators off at night without one of two big things:

a) a crazy number of batteries -- so expensive it wouldn't be worth it, or

b) big increases in the efficiency of your refrigerators -- which could take lots of time, effort, and/or money but might pay off in the end.

Option b) has the advantage that, if you take sensible incremental steps, you end up with lower fuel bills instead of a wasted fortune in dead batteries.

How would you know? You have no biz answering any questions.

MOD NOTE: Sunking we know you do not agree with Dan but I will ask you to please stop making these type of posts against him.

[DanKegel]

You can look into upgrading appliances to more efficient ones, but that also has a large up-front cost.

One of the mantras of this message board is that people should look at improving efficiency before going solar. This is especially important for off-grid systems.

Have you measured what appliances and lights are using how much energy?
Have you switched to LED lighting yet?
What model, year, and size of air conditioners, refrigerators, and freezers do you use?
- Dan

[jflorey2]

15 to 20 kWp of solar panels can be installed on roof.
It looks like the power delivered by the Gen isn't constant enough so that it will damages the electrical devices in the long term.

I already have ideas in mind but I don't know if I can give brandnames of products here. If yes i will expose it.

So what are your thoughts about this project? possible? Impossible? Too expensive? ROI too long because of battery cost?
What do you reckon?
Any advice/idea is more than welcomed

I have some questions too:

- I wonder if an uninterruptible power supply can be used with PV power and gen at the same time.

OK Popeye some notes.

First if you are damaging devices with your current generator you'd benefit from either a generator support inverter or a double conversion UPS (which can be implemented with an inverter/battery system.)

But even before that - start getting your power consumption down. If the generator is damaging your compressors for your refrigeration units it is very likely that replacing them with more modern compressors would both improve efficiency and make them more immune to transient damage from the generator's poor power quality. Lighting/heating loads - same thing, If you eliminate heating loads, get better motor drives and go to more efficient lighting then you'll reduce sag and turn-on transients, which in turn will improve power quality.

So step one is to become as efficient as possible. That will improve reliability and increase generator run time.

Next step if you want to take it is a UPS/inverter system. Three Outback Radians would give you a 24 kilowatt 120/240 volt system with generator support. The battery pack required will be large, but provided you can shut down most loads at night (like freezers, if they will retain cold long enough) you can significantly cut down on generator run time. Run it only when the restaurant is open, and rely on batteries at night or during "slow" times. Batteries are expensive of course so make sure that financial tradeoff makes sense to you.

Next step, if all that works out, is to go solar if you still want to. You can get charge controllers and directly feed the inverter's 48 volt battery bank with the output from the solar array. It is unlikely you'll be able to stop using the generator but it may reduce run time further.

[Logan005]

dan Foss makes some smaller 24 volt DC compressors, and HotSpot makes a variable 48 volt outdoor condenser that can be configured to run ice maker and walkin, still need lot's of batteries for night run. appliance efficiency is most important, on many islands they use chest refrigerator/freezers to further reduce the run time.

[Sunking]

dan Foss makes some smaller 24 volt DC compressors, and HotSpot makes a variable 48 volt outdoor condenser that can be configured to run ice maker and walkin, still need lot's of batteries for night run. appliance efficiency is most important, on many islands they use chest refrigerator/freezers to further reduce the run time.

Dan Foss makes great equipment, but absolutely cannot work in a commercial operation where the unit is opened/closed hundreds of times a day. It would never get cold enough with the compressor running 24 x 7 before it burns up.