How much Solar Power we would need for 5 Dell Servers to run 24x7 ?

[soamz]

Exactly.
Its less than 3700w even.
Thats why.

[SunEagle]

Hey guys, first post here.
I thought I'd look for a forum on solar panel discussions and this seems to be a popular place.

I however have noticed that some regulars here sure seem quick to deter people from going solar.
I know that some people who have no idea and who have crazy pipe dreams of free energy with little investment and maintenance need correction and the sooner the better for their own good. That is understandable.

But how does a question like this:

"5 Dell Rack servers / Dell Servers Power Rating are 750w, 2 power plugs for redundancy."

Become this???

"Panel Wattage = 34,000 watts. Roughly $50,000 USD, higher outside USA
•8 x 80 amp MPPT Controllers. Unit Cost $700 each x 8 units = $5600 USD higher outside USA
•Batteries = 675 Kwh capacity. 48 volts @ 14,000 AH. That is a battery that weighs 40,000 pounds/ 18150 Kg and cost you $140,000 every few years. You will need a dedicated large room with enforced floor to hold the weight with air conditioning year round. The room and mechanical systems wil cost more than the batteries. Who cares right?
•50 Kw Diesel Generator, 500 gallon Diesel tank, 48 volt 800 amp Rectifier, concrete pad another $40,000 out of your pocket.
•Misc hardware Inverters, wiring, shipping, and all the other crap to make it work another $40,000 USD"


Where on earth did that 34,000 watt number come from?

I'm new to Solar but not to electronics.
5 servers would need 3,750 watts when running at full load plus a litte bit for the routers and switches (maybe a few hundred watts max).

I'm sure you design the system a little over for unforeseen things and for some upgrades but dang, being told he needed a system that is enough to power three houses was a little excessive, don't ya think?


I've seen some similar replies in some other threads and I don't want to step on a bunch of toes as I just found this site but I just think this response to the question was a bit out there. .

First off welcome to Solar Panel Talk

Hopefully I can explain where that 34,000 watt number came from.

You are correct that 5 servers will total 3750 watts but that is an instantaneous load and you need to calculate how many watt hours they will use in a day. If they are being run 24 hours then the amount = 3750w x 24h = 90000wh or 90kWh.

With a solar / battery system you need to put back more watt hours then you take out. So if you use 90kWh you should put back about 1.20 % or ~ 110kWh. With an average amount of sunlight isolation at say 3.2 hours (more in the summer and in most places less in the winter) you would need about 34kw of panels (110kWh / 3.2h ~ 34kw).

It is a matter of physics and science that solar can save you money but requires a lot of up front investment to build a system that can power high wattage loads. Adding a battery system just raises the cost by 2 - 3 times of a simple grid tie system.

So it is not that some of us are trying to push people away from solar. We are trying to teach people that maybe solar is not as cheap as you are led to believe and you should not go out an purchase anything until you understand the true costs.

Best plan to use solar is a legal grid tie system without batteries. That has a chance of paying for itself in a few years. A battery system (using today's' technology) will never pay for itself.

[cebury]

Yeah I'm always shocked to see how high the costs and hardware skyrockets, but from reading so many of the experts posts here it makes sense mathematically. You account for peak load, otherwise they shutdown or otherwise don't operate correctly. Then recharging and max operating time on battery and up it goes. Gets far far worse for completely off grid, as you have to account for the relative short recharge time during sunlight when you are also using the most draw. Just from the little I've learned here...

[cebury]

A battery system (using today's' technology) will never pay for itself.

. Here is where I disagree. It could pay for itself the very first time the system goes down. Just depends on what is running on the servers as it could be an online commerce system or could serve expensive hourly employees. Lawsuit avoidance, reputation destruction, etc are other reasons. But once get that far you usually aren't askKing for help on a forum but hiring a data center designer or Sunking.

[SunEagle]

. Here is where I disagree. It could pay for itself the very first time the system goes down. Just depends on what is running on the servers as it could be an online commerce system or could serve expensive hourly employees. Lawsuit avoidance, reputation destruction, etc are other reasons. But once get that far you usually aren't askKing for help on a forum but hiring a data center designer or Sunking.

I will clarify myself. A solar/battery system that is used daily will cost you many times more to generate the same amount of kWh that you can purchase from a POCO.

As for emergency backup, a UPS has been very instrumental in saving computer systems from crashing causing loss of revenue. But those batteries are not used very much or very long. A data center will always have the battery as a short term backup followed by a generator for extended backup.

It just comes down to economics and right now batteries cost too much to run standard home loads but has a justification to run critical loads for short periods.

There is a big difference in both those uses.

[TrueMetalGeek]

First off welcome to Solar Panel Talk

Hopefully I can explain where that 34,000 watt number came from.

You are correct that 5 servers will total 3750 watts but that is an instantaneous load and you need to calculate how many watt hours they will use in a day. If they are being run 24 hours then the amount = 3750w x 24h = 90000wh or 90kWh.

With a solar / battery system you need to put back more watt hours then you take out. So if you use 90kWh you should put back about 1.20 % or ~ 110kWh. With an average amount of sunlight isolation at say 3.2 hours (more in the summer and in most places less in the winter) you would need about 34kw of panels (110kWh / 3.2h ~ 34kw).

It is a matter of physics and science that solar can save you money but requires a lot of up front investment to build a system that can power high wattage loads. Adding a battery system just raises the cost by 2 - 3 times of a simple grid tie system.

So it is not that some of us are trying to push people away from solar. We are trying to teach people that maybe solar is not as cheap as you are led to believe and you should not go out an purchase anything until you understand the true costs.

Best plan to use solar is a legal grid tie system without batteries. That has a chance of paying for itself in a few years. A battery system (using today's' technology) will never pay for itself.

I'm in the Arizona desert and I'd hope to have more than 3.2 hours of good generation even in the winter. LOL
I guess you were sizing that thing for off grid and charging batteries for off solar production hours based on winter daylight hours.
Batteries do cost a ton and it's weird how slow battery technology, and solar technology for that matter, has advanced in the last 30 years compared to everything else.
Being on grid would be way cheaper for sure. Unless he's in the boonies with no utility power and is online via some sort of microwave transceiver. HA


As for my home I've got a quote for a solar system, on grid, that is a 6.2 KW which is too small for me. I am thinking more like 10kw or more.
But I have a 2 story home with a 4 sided roof and I guess that triangle shaped sides kills the square footage to mount them things.
They are quoting about $145 monthly to buy it over 20 years. Seems kinda high for only 6.2kw
A guy at church has a lease where he is paying $110 a month for a 11kw system that was actually more than he needs as his house is half my size.

I am an electronics geek and contemplated doing DIY a few times but it still costs some money and research especially in something you don't do on a regular basis.
If I can't get a large system I have considered building some home brew microprocessor based load controller to only allow one A/C to run at a time etc during the day and then no limits at night when on the grid when it don't matter.
And I might add some VFD's to my A/C compressors which could provide a soft start function as well so you don't need a large amount of current to start the compressors. Which is about 140 amps per A/C @230VAC for a brief second and then 20 amps each max to run. 6KW would barely run one of those. I'd like 10KW so I could run the water heater etc. Which I also plan on modifying some day by installing a 2 ton water source heat pump I could use to heat it at less power. Like 10 amps rather than the 20 amps that a heating element needs.

[SunEagle]

I'm in the Arizona desert and I'd hope to have more than 3.2 hours of good generation even in the winter. LOL
I guess you were sizing that thing for off grid and charging batteries for off solar production hours based on winter daylight hours.
Batteries do cost a ton and it's weird how slow battery technology, and solar technology for that matter, has advanced in the last 30 years compared to everything else.
Being on grid would be way cheaper for sure. Unless he's in the boonies with no utility power and is online via some sort of microwave transceiver. HA


As for my home I've got a quote for a solar system, on grid, that is a 6.2 KW which is too small for me. I am thinking more like 10kw or more.
But I have a 2 story home with a 4 sided roof and I guess that triangle shaped sides kills the square footage to mount them things.
They are quoting about $145 monthly to buy it over 20 years. Seems kinda high for only 6.2kw
A guy at church has a lease where he is paying $110 a month for a 11kw system that was actually more than he needs as his house is half my size.

I am an electronics geek and contemplated doing DIY a few times but it still costs some money and research especially in something you don't do on a regular basis.
If I can't get a large system I have considered building some home brew microprocessor based load controller to only allow one A/C to run at a time etc during the day and then no limits at night when on the grid when it don't matter.
And I might add some VFD's to my A/C compressors which could provide a soft start function as well so you don't need a large amount of current to start the compressors. Which is about 140 amps per A/C @230VAC for a brief second and then 20 amps each max to run. 6KW would barely run one of those. I'd like 10KW so I could run the water heater etc. Which I also plan on modifying some day by installing a 2 ton water source heat pump I could use to heat it at less power. Like 10 amps rather than the 20 amps that a heating element needs.

The OP started out by asking for a solar "off grid" system for his servers. It was later that he mentioned "grid tie" which got confusing because going grid tie solar would be the first step followed by whatever is needed to mitigate a short term power outage. As you stated batteries is still not the most economical way to run loads for long term but work well for short "ride through" power issues using a UPS.

It sounds like you are looking at a large pv system to power everything in your home. I might suggest that you go with a Thermal solar water heating system instead of an electric one. That might allow you to reduce your panel wattage a little.

While I understand your ideas of using solar and some type of controls to run an A/C load, I will tell you that like the batteries system running A/C loads directly from a pv system has it's obstacles. Efficiency is a killer as well as the weather. Without the proper amount of sunlight you would still see a need to run the A/C but not have the enough sun's energy to do so.

Over all a solar grid tie system will reduce your electric bill and pay for itself (even if there isn't any Net Metering payback from the POCO) in a reasonable time period. As long as you don't make it too complicated which tends to drive up the initial cost and string out the payback period.

[TrueMetalGeek]

While I understand your ideas of using solar and some type of controls to run an A/C load, I will tell you that like the batteries system running A/C loads directly from a pv system has it's obstacles. Efficiency is a killer as well as the weather. Without the proper amount of sunlight you would still see a need to run the A/C but not have the enough sun's energy to do so.

Yeah naturally there will be days that you need to tap into the grid when their are clouds or weather but in my area those days are far and few in between.
Also when overproducing you get a 1 to 1 credit ratio with the utility company so you can bank those kw of power to use later, at night, etc. Which is another reason I want more like 10KW vs the system they proposed so far.

As for the A/C units, they are the original piece of junk units that came with the house.
I am a commercial HVAC tech so I will eventually replace them.
However, the geek side of me has me imagining maybe setting up something more custom as far as the outdoor units go. We use heat pumps. But I only need heating when we get a cold snap. Otherwise the use of TV's, computers and lighting keeps our home plenty warm. Often we have windows open during the day as we are doing now to keep it from being too warm.

I have a few VFD's that might be good that we took from equipment at work a few years ago that could run A/C compressors but I'd have to install 3 phase compressors to do so. The soft start function of the VFD would get rid of that inrush current typical to a compressor startup that a solar panel alone would have no chance of providing.
Plus I could stage my A/C units to vary the capacity. In Arizona the A/C are sized for the really hot days and then are grossly oversized for nights and mild weather times of the year.

[TrueMetalGeek]

You mentioned having a UPS for emergencies. I also have a server grade UPS that I took home from work and was able to fix for myself. It is a 2200 watt RMS UPS.
I seriously ran a circular saw on it and cut a 2x6 to test it. HA. It isn't made to run inductive loads like that but it did.
It takes ten 12v batteries in series. I was able to slow charge them for a few days and get them to work again.
It can run 300+ watts of my large PC and monitor plus accessories for an hour or two.
For an emergency I can plug other household things into it.
It weighs a ton though. One person can barely move the thing.

[Sunking]

. Here is where I disagree. It could pay for itself the very first time the system goes down.

You are comparing apples to oranges. SunEagle and I are talking about a Off-Grid Solar system to run critical operations which is just plain nuts. Heck still foolish for anyone to do. Off-Grid systems should be avoided if there are other alternative and no alternative is less expensive, efficient, or as clean as commercial power. People do not understand Off-grid is extremely expensive and horrible for the environment. Nothingg green about it except the cash leaving your pockets.

You are talking about Emergency Stand By Power. Every critical mission system like a Data Center, Telephone Switching Office, Cell Sites, 911, Military, etc uses batteries for Emergency Power only when there is a COMMERCIAL POWER FAILURE. It can either be in the form of a UPS, or from 48 volt DC Power Plant. 99% of the time the batteries sit there, collect dust, and never ever used. Only used when and if ever needed. But they would never be charged from Solar.

Secondly the batteries are sized to run the data/communications equipment for a very short period of time in something like a UPS, and up to 12 hours in a 48 volt DC plant remotely located in a unmanned facility. That do not have to be large because most critical systems have large generators (some even use 2 for redundancy) on site that start up automatically and take over until commercial power comes back on. So the batteries are only on-line for just a few short minutes, then recharged as quick as they were discharged in a few short minutes.It is all done with reliable commercial and deisel power for emergencies.

The OP stated he wanted Off-Grid Solar which is nucking futz. Here is a piece of information no one has even though about. A Data Center, Switching Office or whatever communication facility we are talking about the large power user IS NOT the data and communication equipment. Nah that is peanuts. The big user is the HVAC system trying to keep the place from melting down. No communication system facility has heat, not even if they were located on the Poles. They need massive amounts of cooling 24 x 7 x 365.

The only two data centers I know of that use Solar to supplement their energy needs is Google and United Parcel Service and Wall Mart. But do not go postal it is not because they believe in it or economical because it is not. None of those 3 companies paid for it, you did and it was stolen from you and you never knew it. It was all paid for buy electric rate payers and your tax dollars. It saves those companies thousands of dollars a day in electricity or about 10 to 30% on their electric bill. They do it because it saves them money and allows them to say they are Green and care about the environment. Don't believe one word of it. They could care less, it is about green, but in the form of money. Very simple business decision. They used your money to make them money, and to make themselves look good.