What Impact Will 2.6 MW Solar Have On My Demand Charge?

It will have a negative impact on your demand charge. It should get smaller.

Now if you wish to know more, you will have to post your present usage, amount of daylight per year, a copy of your power distribution contract, the name of your lawyer and electrical engineer, your social security number, local business banking account number and pin number and somebody will get back to you.

Aw gee. I was hoping to at least get the OP to admit that he didn't post enough information for us to help first. I was wondering how much they might have revealed of my silly list.

But once again you are correct. There's a possibility that a very large solar array will not provide power at the needed time.

Sorry, I think ruined your plans...

I was a little afraid he may have actually thought he needed to provide all of that info... but then again, anyone with 2.6MW of solar power is not likely to be in the US, so he was probably still trying to figure out what a Social Security number is!

Actually we are in the US, and this is planned to be installed on the top of our building. Our demand varies from 5 to 8 MW depending on what is happening and the time of year. Our peak demand times are 1300 to 2100 with our peak hitting about 1500.

Well in the summer time the start of your peak demand time, 1300, will be the peak solar power delivery time of the anticipated 2.6MW. (I assume you're on DST and that your time references are local time and not Zulu.) So as I mentioned earlier the demand draw from the grid will be reduced during this time. Unfortunately as you continue to draw your peak power usage, the sun will slowly set over the horizon. So as JRaef predicted, you will not affect the peak demand at all unless you can somehow save and later release the power your solar array was capable of grabbing during the morning hours. You likely will be able to change the time of day for your peak demand but since part of the peak time will be after sunset the potential size of the peak demand will not change at all.

GA for you redfred. Couldn't have said it better myself.

Might easier to adjust your production schedule to match your solar farm peak output if a reduction in Peak Demand charges is the goal. Hopefully you are using a tracking system in your solar farm as well so that you can keep producing as long as possible.

A tracking system will improve the power captured but it will mean only that the captured power drop will more closely track a sine wave roll off instead of a sine squared roll off. The added power drain to get this slight improvement may not be sufficient to offset the power lost in moving the array and would considerably complicate the array. This kind of a detail choice selection would have to be done with complete plans in hand and not just a few paragraphs of discussion.

I don't disagree, for sure a tracker that consumes as much or more than it gains is pointless. But not all trackers are created equal, some actually do increase the output significantly more than they consume in doing the tracking. And that sine wave decremental approach can mean added output at the edges of the productivity cycle, which may help his peak demand. The main point I was trying to get across was that the real help towards using the solar farm to address peak demands is going to come from adjusting the timing of the peak demands.

And of course, this warrants a lot more detailed analysis that we are going to be able to do here. Hopefully, on a 2.6MW farm, someone has done that due diligence!

Good discussion.

What is a demand charge ?

You have a large system and I am jealous as you should never have to buy electricity from a supplier again unless you have a big factory.

You will need to supply much more information, such as what is your current load, peak demand, factory/foundry details (to help with load modeling) etc and more details on how you have (your companies own personal?) 2.6 MW solar farm connected.

Do you really have your own solar farm to provide your (factory/foundry, etc) base load or is this a theoretical (pricing?) exercise? What about peak demand energy storage or island-mode (off grid) operation, as these are not mentioned either?

Please provide as much detail as you can as the more information we have the easier it is to offer advise.

The odds of this having a significant impact on your demand charge are not good. At best the reduction would be 2.6 MW times your demand rate. Assuming you pay $10 per kW, then you would save $26,000 per month. At worst you would save nothing. Keep in mind, that most utilities base their demand charge on a single high peak, usually over a 15 minute window. If you have a totally overcast day and don't get any output that day, you have wasted all your efforts at demand control. You will still save money on energy, but not demand. Some utilities may not guarantee to make up the difference is you lose capacity or they will tack on a charge to cover having capacity available in case you lose your solar input. To answer your question requires a lot more data. I recommend you ask your utility company and they should be able to work with you on an answer.

Everyone who commented could be wrong. Your question is too vague. When is your peak demand and what is the utility schedule (TOU, Season, Tier Usage, etc.?) You might wipe out all of it or you could gain nothing. You would wipe out all of your non peak demand charges. What are those costs? 2.6MW multiplied 4 Peak Sun Hours (a guess) multilplied by 75% for losses would equal 7.8MWh/day for a yearly average. No can know unless you do cost analysis and see what the ROI truly is.