Power monitoring

booboobooboo Posts: 39Solar Expert
I am looking at installing a grid-tied system and am trying to figure out how much solar I need. Is there a way to monitor your daily power usage other than looking at your meter on occasion? It would be nice to have a device that willtell you how much you are using at any given time and keep a history.

I do have a Kill-a-watt device that allows me to check things that are plugged into a wall recepticle but it does not work for anything else.

Comments

  • BB.BB. Posts: 27,782Super Moderators admin
    Re: Power monitoring

    There has been discussions here before about T.E.D...

    The above meter looks fine and is relatively easy to install.

    However, if you install Grid Tied Solar--TED does not do "net metering"... So, if you meter spins backwards, TED will still be going forwards. Therefore, they are not very useful once you have your solar panels up and running.

    There are other devices out there too (like this), but finding one that works with "net metering" (power consumed, vs power generated on the same feed) look like they are not common.

    Using your utility meter and reading it once a day or once a week is probably how you will have to go (or just look at your bill).

    You can also time the meter dial and use the Kh factor (12 WH, 7 WH, etc. per revolution) and check your current consumption rate...

    i.e., meter takes 30 seconds to spin with a 12 Watt*Hour per revolution Kh factor (Kh factor should be on face of meter, revolution is the spinning of the metal plate--or sometimes LCD "spinner"--how many seconds for 1 full revolution)...

    12 WH * 3,600 sec per Hour * 1/30 seconds per revolution = 1,440 watts...

    Of course, if the meter is turning slow, you can count 30 seconds for a 1/4 revolution and say it is 120 seconds per revolution and plug it into the above equation.

    Some meters have a contact or IR LED that makes/breaks/blinks once every revolution. Again, this has the problem it will not matter if your meter is spinning forwards or backwards--the pulse is just a pulse.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • booboobooboo Posts: 39Solar Expert
    Re: Power monitoring

    My electric company does not do net metering and my meter is digital so it does not spin. Looks like Ted is a possible solution.
  • BB.BB. Posts: 27,782Super Moderators admin
    Re: Power monitoring

    How does your utility plan to manage Grid Tied? With a separate meter for your grid tied inverter. Or a reprogrammed digital meter where they will charge you (made up numbers) $0.10 per kWhr for consuming power and pay you $0.05 per kWhr for generating it?

    1 Year Net Metering is probably best for the consumer (certainly not best for the utility)--anything that reduces your return makes Solar Grid Tie a less interesting investment.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • booboobooboo Posts: 39Solar Expert
    Re: Power monitoring

    The deal is they will pay for half of your setup up to $4 per watt. But you give them any excess power for free. You are not allowed to have batteries or generators. I plan to talk to them tomorrow to get all of the details and contracts. If you are interested I will let you know the total deal.
  • BB.BB. Posts: 27,782Super Moderators admin
    Re: Power monitoring

    Thank you BooBoo,

    I don't live in Arizona--so I was more interested in having your information/experience posted here for others.

    Never thought about it before visiting this forum--but electric utilities and regulations/laws are very local (by state, county, city, utility). So--pretty much my interest is to let potential solar grid tie customers know about possible stumbling blocks so that they don't get blind-sided later with their projects.

    In many areas, it is pretty difficult for a first time customer/home owner to do their own engineering/contracting/design/permitting of a Grid Tie system themselves...

    Once a person has gone through one or two of them--you get to know the systems, local building department, and utility people--it makes the process easier as a do-it-yourself project (will normally still need find a licensed electrician and Professional Engineer for the paperwork and sign-offs).

    Best Wishes and Good Luck!
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • booboobooboo Posts: 39Solar Expert
    Re: Power monitoring

    My fathers house is off the grid completely, he has a pretty good handle on the stuff so I don't think installation will be a problem. I am in the real estate business so getting an electician to finish it up or sign off on it will not be a problem. I am not an electrician but know how to do the work and know most of the building codes.

    I am still confused on the tax credits though. Maybe someone here can clarify this. If I spend $6000 for a 1kw system and my electric company give me $3000 back as a rebate. Do I get 30% of the $6000 or the $3000 left after the rebate? I would get $1800 for the $6000 and only $900 for the $3000.

    The state of AZ also gives 25% up to $1000. If they give me 25% off the $6000 it would be $1000 if they give it off the $3000 I would only get $750
  • n3qikn3qik Posts: 741Solar Expert ✭✭
    Re: Power monitoring

    Can't say for state, but Fed is applied to what is left AFTER local and state rebates are subtracted from total cost.
  • booboobooboo Posts: 39Solar Expert
    Re: Power monitoring
    Can't say for state, but Fed is applied to what is left AFTER local and state rebates are subtracted from total cost.

    That is the oposit of what I was told by the solar store.

    I also got quotes $1200 for 170w pannels and $12,700 for a complete 1.5kw system installed.

    I was not able to get a hold of the sponser of this forum yet.
  • Solar GuppySolar Guppy Posts: 1,959Solar Expert ✭✭✭
    Re: Power monitoring

    $1200 for 170 watt is 7 dollars a watt, which is the most expensive I have seen anywhere

    Just about any retailer has them for under 5.00 watt

    http://www.ecobusinesslinks.com/solar_panels.htm

    If your into getting seconds ( cosmetic blemishes ) http://www.sunelec.com/ for "B" grade 4.22/watt or "A" grade for 4.50 watt

    As to the Fed 30% Tax Credit ( maximum back to you is 2K ), its on the Net Cost, you can't get a credit for something you didn't pay for ... if your getting advice otherwise its wrong
  • booboobooboo Posts: 39Solar Expert
    Re: Power monitoring
    $1200 for 170 watt is 7 dollars a watt, which is the most expensive I have seen anywhere

    The other solar store here in town just quoted me $1400 for a 170 watt pannel.
  • nielniel Posts: 10,311Solar Expert ✭✭✭✭
    Re: Power monitoring

    naws, our forum sponsor, has suntech 170s for $807.50 and mitsubishi 170s for $829 singly priced right now. you can get a better price for quantities.
    http://store.solar-electric.com/hiposopa.html
  • BB.BB. Posts: 27,782Super Moderators admin
    Re: Power monitoring

    As always, check shipping / insurance charges... Basically shipping big/thin glass windows around--takes good packing and a good shipper to get them to your place safely...

    Check ask around/many times shipping costs for 1 or 20 panels is almost the same--so sharing a panel purchase/group buy to the same area (or purchasing locally from a large installer and piggy-backing on their order) may end up saving some money.

    Solar panels are popular right now--so it is difficult to buy them at discounted rates right now.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • booboobooboo Posts: 39Solar Expert
    Re: Power monitoring
    The deal is they will pay for half of your setup up to $4 per watt. But you give them any excess power for free. You are not allowed to have batteries or generators. I plan to talk to them tomorrow to get all of the details and contracts. If you are interested I will let you know the total deal.

    I talked to my electric company again and they told me that when they decide to do net metering they will allow me to sell power back to them even if I take the rebate.
  • BB.BB. Posts: 27,782Super Moderators admin
    Re: Power monitoring

    Booboo,

    On the metering and "excess power" to the utility is for free...

    A) Will the meter turn backwards during the day and forwards at "night" (i.e., basically becomes 1 month net metering and any possible "excess" generated power is dropped from the bill--and you get the ~$5 per month minimum usage charge).

    B) is the meter setup to never turn backwards with a one way clutch--or setup electronically (or with some meters, they can be setup to turn "forwards" even when the current is flowing backwards--i.e., charging you for the privilege of giving them free power)?

    If A) then a small system will be OK--because the power you use over the 24 hour day / 30 day month, you will use more at night (and during the summer with A/C) than you will ever generate with a small solar system.

    If B) then, during the day when your not at home and the loads are very light (no A/C, no fans, maybe the fridge and such running--a few hundred watts vs the 1,000 watt pk output of your proposed system)--it is very possible that you will be generating much of your power when your loads are very low (at work, no A/C--especially during cooler weather)--so any solar system would be a waste with a home that uses little power during the day time (~9-3pm with nobody home)--and the meter will never turn backwards during this time (1,000 watt PV system - 200 watt load = 800 watt free to the utility). And your solar system becomes pretty much useless to you (unless you turn on more loads during the day).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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