PV Vs. Diesel

[Talal]

Hello,

I am looking to replace a 50KVA diesel generator with a off-grid 40KW Solar PV system.

I have a few questions, and I am hoping to get some advice from the helpful folks here:

1. Regarding the system, is it better to buy separate components and customize the systems, or is it more cost effective to purchase from a single solution provider?

2. Regarding cost of the system: I realized that ~ 1$/Watt is a standard price for a PV panels, what about a balanced system including battery banks?

3. What is the best path to pursue such system?


Any response is much appreciated.
Thank you.

[SunEagle]

Hello,

I am looking to replace a 50KVA diesel generator with a off-grid 40KW Solar PV system.

I have a few questions, and I am hoping to get some advice from the helpful folks here:

1. Regarding the system, is it better to buy separate components and customize the systems, or is it more cost effective to purchase from a single solution provider?

2. Regarding cost of the system: I realized that ~ 1$/Watt is a standard price for a PV panels, what about a balanced system including battery banks?

3. What is the best path to pursue such system?


Any response is much appreciated.
Thank you.

Without getting into details the cost for a off grid battery system is very very expensive. My recommendation is if you go with a solar pv system do not to get rid of your diesel generator or upgrade to an LPN generator which would be cheaper to run.

[inetdog]

... upgrade to an LPN generator which would be cheaper to run.

LPN?
LPG may not be cheaper than diesel or gasoline but will be safer to store than gasoline.
Piped NG (from the utility) will be cheaper in any area where it is available. CNG and LNG are more exotic.
In the case of a major disaster NG is as likely to be shut off initially as the grid.

[SunEagle]

LPN?
LPG may not be cheaper than diesel or gasoline but will be safer to store than gasoline.
Piped NG (from the utility) will be cheaper in any area where it is available. CNG and LNG are more exotic.
In the case of a major disaster NG is as likely to be shut off initially as the grid.

You are correct LPG. Funny how the mind and hands don't work after a few beers.

I believe LPG is more efficient fuel to run in a small generator. And it is cheaper than either gasoline or diesel if you purchase it from a tank truck to fill up say a 100 gal tank.

[Talal]

Without getting into details the cost for a off grid battery system is very very expensive. My recommendation is if you go with a solar pv system do not to get rid of your diesel generator ....

Assuming I will not get rid of the diesel generator. But knowing that the operational costs of it is ~ $15,000/month, and the need to install a 40KW is essential. What cost range would you think I will be looking at, for the battery banks?

[russ]

How many kWh are you wanting to generate in a day?

Consumption - Around the clock or certain hours?

Largest single consumer?

Type of consumers - lighting or motors for example?

[Mike90250]

You are looking at quite an extensive PV system. Also keep in mind, that the installed panels only produce 80% of their nameplate power, and even that is only for 20 minutes at solar noon, with
1 axis tilt adjustment. You will need to keep a generator for cloudy days, as there are no battery banks that will easily cycle 40KWH. That's HUGE !! You may be able to install a "tiny" battery to run some lights and essentials, but this is a huge project.
Other questions, 240VAC or 480VAC ? 3 phase? The inverter package alone, will likely be about the size of a 20 foot shipping container.

[peakbagger]

Bump your system cost to $10 to $15 per KW. Your load profile is critical to figuring out how to proceed. Generally a Diesel generator is purchased to cover the maximum load required. If you need a constant high load, the system is going to look far different than if you have a typical load which is farily low most of the time with occasional surge loads.

[Talal]

How many kWh are you wanting to generate in a day?

Consumption - Around the clock or certain hours?

Largest single consumer?

Type of consumers - lighting or motors for example?

1. I am looking at an average of 160-170 Kwh per day.
2. Consumption is among uncertain variable hour (day and night)
3. Largest single consumer are machines
4. Lights are in the facility needed to operate most of the day + several medical machines + computers chargers etc.

[Talal]

You are looking at quite an extensive PV system. Also keep in mind, that the installed panels only produce 80% of their nameplate power, and even that is only for 20 minutes at solar noon, with
1 axis tilt adjustment. You will need to keep a generator for cloudy days, as there are no battery banks that will easily cycle 40KWH. That's HUGE !! You may be able to install a "tiny" battery to run some lights and essentials, but this is a huge project.
Other questions, 240VAC or 480VAC ? 3 phase? The inverter package alone, will likely be about the size of a 20 foot shipping container.

Thanks Mike for your response.

Having in mind that I need almost a 5,000 KWh/ month, and around 160-170 Kwh a day, will other form of energy storage be suitable?
I presume its 240 VAC. Single phase would be sufficient. Would the inverter size still be of that magnitude with such power load?

[Sunking]

You are still going to have to keep the generator, and you want diesel at that power level. No way aroun dit, plus a nice large 48 to 120 volt commercial battery charger that will likely have to be 3-phase to handle 200 amp 120 volt battery charger.

You do know you are looking at a 48,000 pound battery that will cost you roughly $185,000 to $200,000 every 5 years for replacement don't you? It will need its own building with extensive spill containment and all kind of environmental permits, yearly inspections by local fire departments and environmental protection agency.

[peakbagger]

This might be an apllication for GE durathon sodium sulfur batteries, GE claims they are have a better DOD and longer cycles. Not real usuable for normal off gird folks as they need to be kept hot with case heaters but it might fit the load profile. GE claims to be selling them at a fast clip for remote telecom. Its older tech but they have upgraded it.

[Mike90250]

... around 160-170 Kwh a day, will other form of energy storage be suitable?...

Diesel fuel is a very good form of energy storage, it just takes a few million years to recharge.

It's good you are asking questions, because there is not a cheap, easy answer. To take solar to the
level you are asking, is a very major install, and there is no easy battery bank to suggest for you.

This scale of project will require Engineering, not a simple back of the napkin calculation.

[peakbagger]

The firm I used to work for built power systems for remote facilitites and oil pipelines. They were custom designs that were built to match specific loads and demands. Some of their systems ended up on unattended remote platforms in the gulf of mexico and bunchof them went to the former Soviet Georgia. Many were packaged in shipping containers and were bascially "plug and play". There were some standardized building blocks but each unit was different. Solar was occasionally used but the heavy work was done by diesels when there was high demand and a large battery bank the rest of the time. If you had higher demand the wind/diesel solutions used in remote Alaskan villages works well and substantially reduces diesel usage. The company got out of the system intergation but one of its offshoot s still does it.

As the previous poster suggested, its time to bring in specialized engineering firms as trying to assemble one from reading internet postings isnt going to work. Sure its good to ask general questions that allow you to make a justification for proof of concept, but get your checkbook out, search around for a few remote power systems firms and get a detailed feasibility study done. Then look at the economics and if they still look good make the next step.