Solar Data Center

System · January 2008

Hey folks,

Kicking around the idea of having one of our rooms being supplemented by solar. We have 24 racks and let's say each rack is going to use 40Amps of power at 120volt.

I'm trying to get a ballpark figure on the amount of panels I would need to power these racks for a few hours during a nice sunny Colorado day. Along with this, any other items such as inverter,etc.. (granted, I've done a few hours of research on what is needed but I'm very far from knowing what I'm talking about..) Also, I'm looking for cost for each item as well.

Thanks for any help you can provide,
Eric

BB. · January 2008

Re: Solar Data Center

Eric,

If you are looking for supplemental solar power (as opposed to off-grid and/or battery backed power), you will want to do this with a grid tied inverter.

Problem is that solar power is not cheap... However, utility power may be more expensive, depending on where you live...

Some basic assumptions, $10 per watt for installed grid tie system ($5/watt for panels, $2/watt for inverter, $3/watt installation+permits---just a real rough guess).

From this link, and guessing you are near Boulder CO, a 3 kW PTC rated system ($30,000 list price for 3.5 kW STC rated of panels) would generate about 5,105 kW*Hours of electricity per year (chose this size as a typical installation for a home that uses ~400 kWhrs per month as a rough reference point)...

($30,000 / 20 year life) * 5,105 kWH per year = $0.29 / kWhr (no interest costs, maintenance, taxes, etc.)

Base power for your area is $0.084 per kWhr... (do you have tiered pricing that raises your rates?)

How much power you use per year:

24 racks *40 amps * 120 VAC * 24 hours * 365.25 days / (year*1,000W/kW) = 1,009,843 kWH/year

How much in solar panels would you need:

(3.5kW / 5,105 kWH per year) * 1,009,843 kWH/year = 692 kW of panels

692 kW STC *3.0PTC/3.5STC * $10,000/kWatt = $5,931,000 list price grid tie solar installation to offset 100% of your yearly load...

The above numbers are very rough estimates for a fixed south facing array, no tracking, Grid Tied (assuming your utility allows grid tied arrays). For a system that large, you may be able to cut the price somewhat (volume pricing). But, as you can see, it is not a trivial task.

The nice thing with grid tied solar, it is the cheapest and most efficient use of solar electric PV panels... And you can add it in stages to offset as much (or as little) power as you can afford to install.

It is late--so I may have misplaced a decimal point somewhere--but I think the formulas and assumptions are OK.

The STC and PTC correction factors--STC is the Mfg Name Plate Rating and PTC is the (derated) rating used by California as a more realistic power output number (real world vs lab conditions for solar PV panels.

-Bill

Roderick · January 2008

Re: Solar Data Center

Wow, about 5000 watts a rack!

Well, you can make a start, but it's unlikely that you can power everything from solar.

Companies such as Google, Cypress, and HP have put in, or are planning to put in, solar panels. In each case, it supplies but a small fraction of the electricity the building uses.

HP got some kind of financing arrangement whereby they would not own the panels, but would pay slightly less for the electricity than they would have from the grid (projected costs). I'm sure a project of that size has publicity value, too, though, so I don't know if just anybody can get such a deal. If my figuring is right, your system would be on the order of 120 kW, an order of magnitude smaller than the three listed above. I note also that all 3 above are in California, where rebates make this feasible.

mike95490 · January 2008

Re: Solar Data Center

natter wrote: »

Hey folks,
Kicking around the idea of having one of our rooms being supplemented by solar. We have 24 racks and let's say each rack is going to use 40Amps of power at 120volt.
Eric

5Kw per rack, you will never have to repair your roof again. All the cars in the parking lot will never bake in the sun. You will need a lot of panels ! Does this come out of the IT budget ?

System2 · January 2008

Re: Solar Data Center

This is all just an idea at this point. Our power company doesn't have any solar rebates so either we fund a portion of this or look for a grant of some sort. 5million bucks is a lot of cash but doing maybe 20% of this might be a good idea. Thanks Bill for the great info.

Another idea I had was to do some sort of company partnership. ie. a company buys X amount of panels and we somehow tie that right into their racks. Pipe dream but it migh be worth the PR for that company to spend the money.

niel · January 2008

Re: Solar Data Center

that kind of power requirement is huge for each rack and you will probably want a gridtied type pv system without battery backup to do that of course. the cec rating of the pvs you go with in watts at the efficiency % of the inverter used and minus any other losses like wire resistance will yield the savings in power you have reaped. during sunny periods a rough guess would be working backwards 5000w/.9=5555w cec in needed pvs.
if you've got the large amounts of land area to do this you will need to pay for the system and if you check the store for northern arizona wind and sun you'll see the prices for the pvs with their stc ratings there. for stc to cec(it does vary per module) figure about another 10% needed making this a 6,250w gridtied system roughly needed to power 1 rack. the wires, breaker boxes and disconnects, inverters, etc. will also be needed along with the labor to install all of this. there may still be tax incentives going on the federal level. (not too sure of fed tax breaks so maybe somebody could update) there may also be some help from your state for some installs. check here for your state:
www.dsireusa.org
not to be a downer, but even if you go the mile to do all of this and go greener, you may find the greed of local governments present with a hefty property tax increase as you've now increased the value of the property in doing this. some areas do not tax such renewable energy efforts, but most will so keep that in mind for you to research prior to actually going through with it.

BB. · January 2008

Re: Solar Data Center

Yea, solar driving a data center is not cheap...

In reality, your best bet is to look at conservation first... Your A/C system, looking at ground sourced system (drilling wells, or other source, for constant temperature heat sink/source... usually much more efficient).

Monitoring customer's systems for power usage and sizing of system vs actual loads--installing and supporting green motherboards with power management (newest motherboards/systems have similar strategies to laptop systems for power management). Any power you save putting energy into the black box, you save again because you don't have to use A/C to move it back out side.

Look at co-generation possibilities... For example in some office/computer sites in the San Jose area had natural gas power plants built on property. The electricity is locally produced, and the "waste" heat is used for office heating...

Anyway--many of these solutions are based on very local conditions (that I would be guessing about here) and availability of partnerships for your installation. Your power bill appears to be in the $500,000-$1,000,000 per year range (is it?)... Perhaps it is big enough to attract somebody looking for a partnership (university, company looking for a place to showcase for new business, etc.)...

In the end, your main use of power--computer servers--may not even be in your control to conserve (customer gets what customer wants), leaving you at the fringes of managing your next highest power consumer--A/C. Certainly worth talking with a HVAC contractor to see if you can achieve, at least, a wash between monies saved on power bill being spent on "greening" your heating and cooling systems. You can probably get other "almost free" side benefits from an HVAC upgrade (like "free" domestic hot water)--but if you hardly use any in your office (no cafe, no showers, gym, on-premise other businesses), those co-conservation projects would have limited usefulness per dollar.

-Bill

System2 · January 2008

Re: Solar Data Center

Great points. I failed to disclose that adding solar/wind is the last step in our plan.

Getting rid of our A/C system is our first priority as this is twice the amount of energy as our servers right now. We have this underground tunnel system that NASA put into this place and we plan to pull air from here during the very hot days and outside mountain air during the rest of the year. The hard part is to find something that can blend the hot server air with cold outside air without. We can't obviously have 25 degree air blown in the data center floor.

From here, we offer incentives to new/existing customers to move to virtual private servers instead of colocating lightly used servers. Generating our own power was one of the last things on the list because it costs the most.

If anyone of you have an idea on how to build some sort of regulator that can open a valve/duct from the hot server air and mix it with outside air, I would be all ears. This air has to be 68-73 degrees at all times so this regulator/valve would have to constantly work at it. If the outside air is too hot, then it would just shut down until the proper temperature can be reached. Really, there are 3 air flows. Hot server air, outside air and air from this underground tunnel.

I think it's going to be a fun project. I cannot pay anyone to help as our revenue isn't there yet but starting to think about this is challenging and looking to others for their great ideas is where I'm starting. (sorry, I'm changing the topic from solar to heat exchanger but you guys/gals really seem to know what you are talking about..)

BB. · January 2008

Re: Solar Data Center

Well, you want "Free Consultants" huh....

A couple of ideas--to exchange heat, the ground sourced heat pump is probably the best technological way to make standard A/C systems more temperature efficient.

A big issue with bringing in outside and below ground air for ventilation is that you have nice office air (humidity, quality) and are mixing it with air of questionable quality (humidity, dust, spores, mold, etc.) to extract/transfer heat energy...

A better bet to start with may be to look at Air to Air Heat Exchangers. They are wonderful for home to bring in fresh air but keep the warmth (or cool) of the home in the home instead of dumping conditioned air outside and having to fresh air then condition it (spending ca$h on A/C).

In your case, you might take these type of units and connect your inside air in one loop and your cool air in the other loop--not the traditional use of bringing outside air and dumping stale inside air. This would provide cooling without upsetting your other A/C parameters.

Regarding how cool your air flow--I am surprised a bit that you want such tight regulation... In many places I have worked, the coolers dumped much colder air than 68 degrees. In some data centers I had to work in a jacket because it was literally a refrigerator in the equipment cabinets (granted, this was a government job on a former naval vessel converted to oceanographic research. But the floors typically had cold air vents which vented into the base/front of the equipment bays... Got the cold air where you needed it and the rooms could be pretty normal temperature. When it got hot, then you had the fans stirring the air and spot coolers...

The usual problem we had with getting the cold air--basically, if it was a "normal office style A/C pack", if you tried to run the room cooler than about 68 degrees, then the they would ice up...

You might talk with a few different HVAC vendors and get references from friends/vendors for HVAC vendors that work with Green Projects... Problem is that if you get too far off of the beaten path, you my end up with some expensive problems to fix.

-Bill

Solar Guppy · January 2008

Re: Solar Data Center

well off the top of my head, you can't just use outside air, has to be hudmid/dehumidifed and filtered ect.

Also, one can't just slap something together for commerical building, for many reasons of safety releated, you can't duct tape or 14 gauge some thing together in such a building ..

I also suspect this is an office park building that you lease, you can't touch the building mechnaicals and what ever you do will have to be inspected and approved by the building department

But to your first thought, PV is DOA as you have indicated you don't have resources to do such a project

nigtomdaw · January 2008

Re: Solar Data Center

What does DOA stand for ? sorry thick Hillbilly here !

Is it
Dead Obvious Anwser ?
Dead on arrival
or what ?

BB. · January 2008

Re: Solar Data Center

Dead On Arrival would be my guess... If you don't have the land/money/etc. for solar PV--there is no other (easy/cheap/affordable) way of generating RE power for your company.

-Bill

System2 · January 2008

Re: Solar Data Center

All great points. I understand you can't just blow air into a data center without filtering it, etc...

Our site is out among the hills and we can do whatever we want. The previous owners, NASA, had built exchangers on 3 sides of the building. Their satellite equipment was more tolerable to cold air than our servers are.

As we get closer to building some stuff, I'll see if I can find some local engineers that can help us. Thanks for all the information.

Solar Data Center

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