Jestersix

Electrical cost of running a reef tank in SF

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sfsuphysics

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While this is reef related I thought I'd drop it in here, because it's long, rambling, and mathy.

Recently after talking to a guy over on RDO about moving to SF from NY, I started playing with the idea of installing solar panels on my room, yes even in San Francisco. So I started running numbers, both cost and electricity and came to some interesting conclusions. Now those of you who are hitting $300 a month on your bills then this might not be that much of a surprise but those who have nano tanks and are thinking of a monster setup... could be insightful.

I'll start by keeping things simple, and only count one of my tanks, my 100g stony tank. Over the past few days I've been using my kill-a-watt meter to test various parts of it to get an idea for how much juice it really uses, not wanting to rely on my PG&E bill for a number of reasons... here's one, I don't know how much of that power usage is tank power! So what I came up with with a power usage was.
Heaters (3 - 650 labeled watts total) - 7.62 kWh per day average (granted this can very easily change as it gets colder/warmer)
Lighting (2 - 250W, electronic MH) - 0.51kW x 8hours = 4.08 kWh per day
Pumps (2 vortec, 1 QuietOne4000 return, 1 sedra 5000 on skimmer, 1 rio 600 to keep carbon tumbling) - 168 watts x 24 hours = 4.03 kWh day

And that's all the electrical usage of that tank, granted your mileage might vary depending upon your actual usage. So that adds up to 15.73 kWh per day, and over a 30 day billing period, that translates to 471.9 kWh. Now I'm going to make the big leap and go on the under-estimate side of things and assume that's the only power that I use at all in the whole house, no tv, no lights, no refridgerator, nothing.. and this is a BIG underestimate.

PG&E rates for standard E-1 service (what most people have) are as followed.
Baseline Usage...............$0.11556
101% - 130% of Baseline..$0.13139
131% - 200% of Baseline..$0.22708
201% - 300% of Baseline..$0.31555
Over 300% of Baseline......$0.36190

It tickles me pink to see that calculate dollar amounts to the 5th decimal place too :D Forget any of that Superman 3 "they round every half cent down" bit :). Another interesting thing is if you use 2x the "baseline" power you start getting charged 3x the baseline price! (more on why this is important later)

Now here again is where your mileage might vary as the "baseline" usage does vary depending upon your area, and can do so GREATLY. Because we don't "need" A/C in the city we get screwed for total electrical usage, which looking at my last PG&E bill during this time of the year my baseline is set at 9.8 kWh per day. So 15.73kWh puts me over that limit. Math stuff next.

The first 9.8kWh costs 9.8 x 0.11556 = $1.13 (luckily they have to round down here because I can't pay in millicents!)
The next 2.94kWh (up to 130%) costs 2.94 x 0.13139 = $0.39
Now luckily the next tier is where I stop, with about 2.99kWh left but at 22.708 cents per or $0.68 per day.

So over all $2.20 per day to run electricity on my reef tank, with this GROSS underestimate, or an additional $66 per 30 day billing cycle.
Now lets assume my daily electrical needs outside of tank, brings me up to the baseline, so reef related is beyond that.
So the first 2.94kWh of tha 15.73kWh is $0.39 cents.
The up to 200% gets you 6.86 kWh @ 0.22708 per = $1.56
The next 5.93 kWh (which is where I'm done) is @ 0.31555 = $1.87
So the total cost $3.82 per day, which translates to an additional $115 per month on your bill!

So you see, a relatively "light" reef setup, that's a little on the large side can be a significant investment, and this is simply electricity!

End Part 1
Part 2 - Solar
 
Next up is the solar aspect of things.

My electric usage is 15.73 kWh per day, so in SF the average winter sunlight, nets about 4 hours of sunlight per day. (Now you might think this is low, but in fact it's not really THAT low, besides this is "peak" hours, so you might trickle some later etc).
So to figure out how much solar power output I'd need, assuming grid connected to sell power back to PG&E and buy it back later. 15.73 kWh / 4h = 3.9925 kW of panels.. almost 4000 watts worth of panels.

Now fortunately the cost of a setup doesn't increase linearly, because a huge chunk of change goes into the inverter to change DC power from solar panels, to AC-pure sine wave @ 60Hz that PG&E will accept, so a 1kW system might cost you $10k, however a 4kW system can be anywhere from $20k to $30k dependent upon parts. Lets stick with the pricier version just for kicks and giggles though. And this is assumed a DIY install, except maybe last step of connecting to the grid, so $30k gives wiggle room both ways. Now lets say you have my usage, and you have the cash to buy a system without getting loans (lets not make this too complicated!)

$30k / $115 per month of my tank = 260 months Which translates to 21 years to pay it off! (yikes!). Now here's where it gets good, incentives! Currently the feds give a $2k tax-credit (free money, not a deduction!), and PG&E gives $2.50 per watt (real watt too, so your system has to work :D) which for a 4000 watt system translates to $10000 off! So your $30k investment just turned to $18000 ($8k if you went with the cheaper system!). Now this would only take 13years to pay off (6 years for the cheapy... assuming it still works :D). San Francisco is also arguing giving rebates for solar, however due to the current cluster fuck of an economy we have you can most likely see that first to go on the chopping block. And the best bit of all of this, this all assumes the cost of power stays this way for the next 13 years, now it's true the cost could go down... but honestly when has power EVER gone down?

Now the great thing going here is that the solar power that you use to sell/buy from PG&E takes the energy usage on your bill from the top, because you're simply are paying the difference in power from beginning of month to end. So you're actually getting more investment for your panels. If you happened have go up to 200% with just your normal electrical needs, your tank costs could be double what they are, FOR THE SAME POWER YOU USE! So the "payback" time for those panels will be chopped in half! And to make matters better, in California if you switch to an E-7 rate, which is "time of use" PG&E by law has to buy back power from you during peak times at the going rate, which for baseline is almost 3x the cost as off peak! So if you don't mind having your tank on a night-cycle for lighting and all that you can sell back power at higher rate than it costs you to buy back! (granted higher tiers of usage have a much smaller return so you'd need to run some numbers).

Other options I've seen, is some companies will install solar panels on your roof FOR FREE! What you end up paying is for how much power you actually use, and last guy I talked to who ran one of these companies it was 11 cents per kWh, so you pay the baseline rate regardless of how much you use! So you don't need any investment on your part.

So while it is true solar panels don't last forever, most companies guarantee to 90% output at 10years, and 80% output at 25 years, and if you buy panels from a company that's been around, where you know they will be there in 25 years then it's not much of a worry.

Bottom line, is in the club we talk about this saving the reefs, etc. Yet our power consumptions for reef tanks typically is the usage of a whole other house worth of power (or more!). And if we're going to worry about stuff that gets thrown into our air, into our oceans, and all of the place, all the aquaculture in the world can't make up for the amount of pollution we put into the air simply by keeping stuff alive.

Didn't mean to sound all soap-box like, just ended up turning out that way :)
End part 2
 
Now I have been told that PG&E only gives credit for extra power and does not pay for KW you generate by connecting to the grid. I have about a $270 a month bill just for the electric portion of my bill at about 1300KW a month use ( I think ) and I have 3 tanks set up a 75 SW, 29 SW + a 10 gallon fresh tank. Still it would be nice to put that money toward paying off your Solar instead of having to pay PG&E every month. You would be one step closer to having no power bill at all.

But then again not too many people stay in one house for that long before moving up.
 
Correct, PG&E doesn't pay you money for power "sold back" but it does credit you, and those credits do last a while, being connected you pay something like 14 cents a day if you happen to break even (or exceed selling back), so you will have a minimum bill. But a $270 bill every month would get me researching solar in a hurry.

As to the moving bit, unless you have a small place and have kids coming I can't see why people would want to move from house to house, California has awesome property tax laws based upon how long you live at a place. But hell if I moved I'd get the ratchet set and take my solar with me! :D Or at the very least add that onto the cost of the house when I sell it. Obviously solar isn't a viable option for those who rent.
 
Steinhart did not go with solar panels simply because it was only sunny less than sixty days out of the whole year in SF. Do you get that many sunny days where you live? I know I don't. Just food for discussion.

Jim (Jimsar) has solar panels on his home in Vallejo, but I don't think it made a huge enough dent into his past reefkeeping hobby.
 
Ok, I might sound like a solar panel salesman for the remainder of this post, just note I am not, I'm still an Physics & Astronomy teacher :D

As much as I love the Steinhart guys I think their non-solar decision was more of an aesthetics thing, either solar panels, or plants on the roof. Not to mention Steinhart is a pretty dense place so I don't know if they really have the sq.ft space to run that whole place, I mean just look at the reef tank! IIRC from Matt's discussion they had 2 or 3 68hp pumps, each one of those MFers are on the order of 50,000 watts each! So I doubt solar would have put much of a dent in their power usage, however the plants probably could help by doing something or other reflecting sun, etc :D

But there doesn't need to be a sun shining down on your panels for them to work, that bright white sky we're very used to, what that is mostly doing is diffusing the light, so instead of a yellow spotlight in the sky, we get a white glow all over, it'll lower your power production no doubt, but only by 10-20% depending on how thick the clouds are, obviously dark and gloomy days not-so-much power either.

Here's an article from a year ago, it doesn't mention size, however it mentions price which seems like it's in the same ballpark of what I"m talking about, and this guy lives in the sunset! (oh it's kind of a long article too btw :D)
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/04/21/HOGAQPAJBS1.DTL

Can't speak for Jim's setup, as I don't recall what he had, 2.5kW? Of course living in Vallejo, he may have been a heavy A/C user as well which could explain why it didn't help his reefkeeping much, but I'm sure it put a sizable dent into his bill had he not had the panels.
 
If you've driven by steinhart, you can see that they did do some solar. They are special clear solar panels that wrap around the exterior of the building. Granted, its not going to power the whole place, but they did do some.

PS. Great writeup Mike!!!
 
Really? Hmm I'll have to take a closer look at Steinhart the next time I do my stroll through the park. I'm curious though about clear solar panels, seems like that kind of defeats the purpose.

But thanks for the kind words. Just had a sudden thought of self-realization that us reef tank owners can be using enough power to power a normal (non A/C'd :D) home or more just with our tanks
 
From my understanding they were actually thinking about using something like sky lights in the Steinhart. Eileen I think that may be what you were talking about that wasn't very feasible.
 
[quote author=sfsuphysics link=topic=3627.msg41803#msg41803 date=1209320408]
Really? Hmm I'll have to take a closer look at Steinhart the next time I do my stroll through the park. I'm curious though about clear solar panels, seems like that kind of defeats the purpose.

[/quote]
Mabe not the right word, the solar cells inset in clear glass panels. It was on the roundabout side(north i think)? The last time we went there they still had the job fencing up so we couldnt go in, but we were tempted to grab our hardhats, vests, and a clipboard and blend in!!
 
[quote author=Raddogz link=topic=3627.msg41782#msg41782 date=1209264967]
Steinhart did not go with solar panels simply because it was only sunny less than sixty days out of the whole year in SF. Do you get that many sunny days where you live? I know I don't. Just food for discussion.
....

[/quote]

Not for Steinhart but at the SFO Airport, they have these Solar Power Trucks and they were wondering why these don't work well like the one they have in Dallas ;D :D ..
 
Actually, I heard it from hisself Bart Sheppard at a Seabay presentation. Someone asked why there were no plans on putting up solar panels on the roof in mass quantity.
 
I kid you not, my electricity bill for April was under $11. Total kwh was under 200, way within baseline. Ah, the joy of having no reef tank. My solar panels, by the way, went online Jan 03. Total out of pocket was ~$12,000 if memory serves me right. No regrets for making that decision.

May 1 to Oct 31 is primetime! Between noon to 6:00 PM is peak period, and time-of-use metering is .28xx per kwh up to 130% of baseline. Since nobody's home at that time, most of the power generated gets sold back to the grid for that price. I buy it back at .08xx after six pm. My biggest electrical consumer right now is the plug-in Porsche.

I'm out of town, I don't have the bills in front of me right now, but I think the numbers are accurate.

Reefers should buy carbon credits! ;D
 
Here's one thing to consider if having Solar. I have a big system that made sense as I have a fairly large electric bill. Now, after loads of issues with my Tank, I considered downsizing to a nano or getting out completely. Then I realized, I'd be generating way to much electicity and giving away a substantial amount to PG&E while still having to pay them a minimum for electricity and for all my Gas usage. The thought is just to depressing, so I'm locked into reefing so that I can use enough electricity.

The other thing that PG&E are doing is discouraging you from moving to gas appliances that would be more efficient than electrical ones because you cant get credit toward your GAS.

Personally, I think you should get credit right down to Zero for both Gas and Electricity. They'd do that if they were honest in their supposed drive to greener sources of energy.

-Adrian
 
Have you thought about converting some of your gas usage equipment into electric? Stoves, Clothes Driers, Space heaters instead of central heating (I mean really when its cold does the whole house need to be warm vs just you?), water heaters (although if going this route I'd propose a solar water heater as they're much more efficient than using solar power to power an electric heater), or a tankless electric water heater in conjunction with solar heating.

As to PG&E, they still need to to maintain all the lines, and while yeah they're pretty tight fisted about some things, I think they really get the short end of the stick by being forced to buy back excess power at your cost vs. their cost during the day. Granted for a user of solar energy that's a godsend, ask Jim :D However if you're connected to the grid they still give you power as well.
 
Mike, your excellent analysis is going to be expensive for me, as it just pushed me over the fence. I don't think I want to mess with solar panels on my two story roof, so anyone have good suggestions for a good solar company? The only one I know is Solarcity, and am pretty sure there are many more out there.
 
Heheh Tong, I'm happy/sorry I'm going to cost you this money, but in the long run it should actually save you much more than it'll cost you, unless of course we find a new power source and then power drops to 4 cents per kWh :D

Occidental power is another fairly large company that does installations.
oxypower.com

I tried using one website findsolar.com but man there's almost too much information in available contractors in this area, that being said, if you don't mind the grunt work of getting a bunch of estimates, could be good thing.
 
[quote author=tonggao link=topic=3627.msg43553#msg43553 date=1211172192]
so anyone have good suggestions for a good solar company? The only one I know is Solarcity, and am pretty sure there are many more out there.
[/quote]

I used RealGoods (www.realgoods.com). They've been in business since 1978, which is one reason I used them. Back then, your choice was a bit limited; either go with a cheaper newbie, or pay a bit more with an established company. There are lots of good vendors out there now, so approach it the same way you would if shopping for a contractor. Compare panel & inverter equipment, because I noticed from some ads that installers are "married" to certain brands. It may or may not be the best or most efficient. Do some homework first; there are a few good forums in the net where you can pick up invaluable information.

Lastly, if you should use RealGoodsdotcom, please tell them I referred you (Jimmy Sarmiento @ Vallejo). Frankly, I don't know what their referral program is, maybe I'll get a propeller cap, LOL!
-Jim
 
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