solar system forming and need help

Godsprovision
Godsprovision Registered Users Posts: 8 ✭
in Solar Beginners Corner #1
Hello. I am new here and in search of help designing my solar system. My monthly average usage has been 940kWh over the last year so I was hoping to be able to produce enough to cover that. I wanted to go off grid with batteries, but I may have to start with grid-tied or grid-interactive. I have learned that I may have trouble getting a permit from my city as I am not a licensed installer. I found out I may also have trouble getting a net meter from my utility company for the same reason. I purchased 14 Sharp 250W solar panels 60 6 x 6 solar cells that are enphase ready. I realize now that I should have designed the system before making this purchase. I am not opposed to selling these and going with different panels instead so they all spec match. I may see if I can get help from a licensed install company to handle the permits and the approvals for the meter. I am going to look at some of the stickies to see what is there along with other areas of this forum. Thank you for your help.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: solar system forming and need help

    Welcome to the forum.

    Let's do some fast math: 940kW hours / 30 days = 31kW hours per day.

    Off-grid? Forget it. Imagine paying $1,000 a month for electricity. How does that compare to your utility bill?

    Grid-tie may be doable because you may qualify for tax credits which would effectively reduce the cost base, but you mention some built-in reluctance on the part of the utility and local authorities. That could be a problem.

    Now you've already bought 3500 Watts of PV. Okay the cart is in front of the horse but you could probably resell them for not too much loss. Gosh, aren't I full of good news? :D

    What would 3500 Watts get you? Grid-tie you can run the numbers through PV Watts and see, but it's not likely to be grand. Perhaps 13kW hours per day? Or about 1/3 what you use. Off-grid it will be far worse: about 7kW hours per day, perhaps a bit more.

    I suggest you invest $30 in a Kill-A-Watt meter and start looking at everything you've got plugged in. Find the parasitic loads and inefficient items. Conservation is your best investment no matter where the energy comes from.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,590 admin
    #3
    Re: solar system forming and need help

    Welcome to the forum Jeremy and Michelle,

    Grid Tied solar really depends on the utility's billing/rate plans as to how best to make for a Cost Effective installation.

    If you have not yet checked with the utility, do it how (perhaps they have a website). For me, in California, our utility has 1 year net metering and Time of Use billing.

    Basically, I pay a minimum charge of $4.50 per month, and any excess power I generate, gets turned into $$$ which is credited to an account. In winter, when I use more power than I generate, the money is deducted from the account. At the end of the year I either pay the negative balance, or the positive credit is zero'ed out.

    Regarding the $/kWH charges... I pay (it is complicated) around $0.09 per kWH for off peak power, and pay around $0.30 per kWH for on peak power (weekday summer afternoons from noon-6pm). So, for me, I get paid 3x more money for summer afternoon power I generate. And I can by "cheap power" off peak (cook, do washing, etc. during off peak--And winter billing is $0.12 or less per kWH).

    Other utilities have different polices--Some of which can make GT Solar power difficult to justify (i.e., you buy power at $0.20 per kWH and they pay you $0.05 per kWH). Other utilities have a high monthly charge ($48 to $96 per month connection fee) and "cheap power" (0.10 per kWH).

    So--figure this out. In many places, paying a licensed contractor to install your system is not bad (some are well under $5.00 watt turn key systems). In some cities and with various utilities, they may make it very hard for a DIY install.

    Power wise--It is pretty simple to estimate the amount of power your system will generate. Use a web site like PV Watts. For Fort Worth Tx, fixed 3,500 array, facing south, tilted to your latitude (and $0.097/kWH):



    Month
    Solar Radiation
    (kWh/m2/day)
    AC Energy
    (kWh)
    Energy Value
    ($)


    1
    4.32
    351
    34.05


    2
    4.77
    349
    33.85


    3
    5.50
    433
    42.00


    4
    5.98
    447
    43.36


    5
    6.02
    457
    44.33


    6
    6.25
    446
    43.26


    7
    6.39
    462
    44.81


    8
    6.31
    456
    44.23


    9
    5.83
    413
    40.06


    10
    5.56
    424
    41.13


    11
    4.43
    343
    33.27


    12
    4.10
    332
    32.20


    Year
    5.46
    4912
    476.46



    So, if your usage has been ~940 kWH per year, in raw numbers, this will offset around 1/2 of your power.

    But, if you do have a "good" time of use power plan, it could work.

    Power wise, you are around average power usage for the US (around 600-1,000 kWH per month). If you have never done much in the way of conservation before (and moving from electric heat to gas/propane/etc., lots of attic insulation, wall insulation, double pane windows, new energy star appliance, etc.), it can be possible to save upwards of 50% of your electrical usage.

    However, as I understand, for folks from the South West, if you use A/C--That is a very low average monthly bill (especially during summer).

    In general, going off grid is not going to save you any money. Typical off grid costs (including battery replacement ever 4-8 years, electronics replacement every 10+ years, and original installation costs) for power run in the $1-$2+ per kWH range... A few people here have gotten it towards $0.50 per kWH--But compared to your (guessing) $0.10 per kWH power costs--It does not fly.

    If you need emergency/backup power, we can talk about a smaller system (say 3.3 kWH per day/100 kWH per month or even down to 1 kWH per day) if you have longer term power outages (months)... If your outages are 2 weeks or less, a genset (natural gas/propane/diesel/gasoline) is usually a better "investment". And for a full time off grid system, you probably would need a backup genset anyway (sun does not always shine).

    In general, pure Grid Tied Systems (no batteries) do not do "backup power". Utility power fails, the GT system shuts down.

    If you are really interested in a "hybrid" power system (Grid Tied + Off Grid power + Battery bank + etc.)--It can be done, but is still will not be cheap.

    Starting with analyzing your current power usage and looking at conservation is usually the best place to start your solar journey. It is almost always less expensive to conserve (and buy more efficient appliances, etc.) than to build a larger solar power system.

    A Kill-a-Watt type meter is a great tool to start looking at your power usage. Outside of Air Conditioning, electric hot water, etc., Your refrigerator is usually a top power user followed by computers and home entertainment systems.

    Your thoughts?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Godsprovision
    Godsprovision Registered Users Posts: 8 ✭
    #4
    Re: solar system forming and need help
    Cariboocoot wrote: »
    Welcome to the forum.

    Let's do some fast math: 940kW hours / 30 days = 31kW hours per day.

    Off-grid? Forget it. Imagine paying $1,000 a month for electricity. How does that compare to your utility bill?

    Grid-tie may be doable because you may qualify for tax credits which would effectively reduce the cost base, but you mention some built-in reluctance on the part of the utility and local authorities. That could be a problem.

    Now you've already bought 3500 Watts of PV. Okay the cart is in front of the horse but you could probably resell them for not too much loss. Gosh, aren't I full of good news? :D

    What would 3500 Watts get you? Grid-tie you can run the numbers through PV Watts and see, but it's not likely to be grand. Perhaps 13kW hours per day? Or about 1/3 what you use. Off-grid it will be far worse: about 7kW hours per day, perhaps a bit more.

    I suggest you invest $30 in a Kill-A-Watt meter and start looking at everything you've got plugged in. Find the parasitic loads and inefficient items. Conservation is your best investment no matter where the energy comes from.

    I appreciate your input and help. I want to install myself, but the roadblocks seem to be the city and the utility company. They may only want to play nice with the licensed install companies. I do not want to go too far down the road of DIY and then have a system I cannot even use. I have some local companies who have quoted systems for a pretty penny. They claim to pay for themselves over a period of time. They also offer financing. I may have to go that route.

    We try to conserve and I mostly have concerns about our older and not efficient electric central air/heat unit. The system will have to be able to handle that current draw unless we leave those on the grid. We really do not use those much. Otherwise, we have just a few other appliances. Electric water heater(possibly being replaced with a hybrid electric unit for higher efficiency), refrigerator/freezer(X2), chest freezer, range/oven, washer and dryer. Yes, I need to put a KillaWatt unit on these to see just how inefficient they are.
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  • Godsprovision
    Godsprovision Registered Users Posts: 8 ✭
    #5
    Re: solar system forming and need help
    BB. wrote: »
    Welcome to the forum Jeremy and Michelle,

    Grid Tied solar really depends on the utility's billing/rate plans as to how best to make for a Cost Effective installation.

    If you have not yet checked with the utility, do it how (perhaps they have a website). For me, in California, our utility has 1 year net metering and Time of Use billing. ...

    Your thoughts?

    -Bill

    Bill,

    Thank you for your help. The chart is helpful. I am much closer to Dallas. Yes, I need to talk to the city and to the utility company if I want to move too much further to DIY. We would like to go to higher efficiency on our appliances. That may be further down the road. It would be nice if it was sooner. We try to only use our central air/heat when absolutely necessary. We definitely should look into double panes windows. Our insulation in the attic is good and we have radiant barrier. The house is well insulated with the exception of the windows. Certainly a weak point. The KillaWatt needs to be one of the next things we do to record how our appliances are doing. I agree there. I really want DIY as it would be less expensive. I want to design a full system and look at the cost vs financing or leasing to own a system.
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #6
    Re: solar system forming and need help
    Godsprovision wrote: »
    Bill,

    Thank you for your help. The chart is helpful. I am much closer to Dallas. Yes, I need to talk to the city and to the utility company if I want to move too much further to DIY. We would like to go to higher efficiency on our appliances. That may be further down the road. It would be nice if it was sooner. We try to only use our central air/heat when absolutely necessary. We definitely should look into double panes windows. Our insulation in the attic is good and we have radiant barrier. The house is well insulated with the exception of the windows. Certainly a weak point. The KillaWatt needs to be one of the next things we do to record how our appliances are doing. I agree there. I really want DIY as it would be less expensive. I want to design a full system and look at the cost vs financing or leasing to own a system.

    Really you have it the wrong way around, do the conservation first so you know how to size your solar system. I think if you run the numbers and get you load profiles you will find you can use considerably less solar if you spend first on energy star appliances, CFL or LED lighting, and if that old AC unit is 10+ years old it is probably time for it to go as well. Mini Splits are much more efficient. Good insulation and double pane windows will drastically reduce you AC consumption. I bet you could cut your solar size in half doing those things first, making your ROI much faster.

    Talk to your utility, they many times have programs to help you conserve energy. Also you have to understand how the net-metering plans work intimately.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
    Re: solar system forming and need help
    Godsprovision wrote: »
    Otherwise, we have just a few other appliances. Electric water heater(possibly being replaced with a hybrid electric unit for higher efficiency), refrigerator/freezer(X2), chest freezer, range/oven, washer and dryer. Yes, I need to put a KillaWatt unit on these to see just how inefficient they are.

    That is quite a heavy electric load. Off-grid you don't want this.
    Electric range/oven = big power demand.
    Electric dryer = big power demand.
    Electric water heater = big power demand.
    All three of these have not only heavy demand on use but also will run up the kW hours quickly. Unfortunately the Kill-A-Watt can not be used on 240 VAC loads.

    Two refrigerator freezers and one chest freezer = about 3-4 kW hours per day right there. Perhaps worse depending on how old they are and how hot the weather.

    The central air/heat unit: is this all electric? Electric heating elements? Or just a heat pump? If not used it probably isn't as big a load contributor as you might think.

    In short the best way to conserve electricity is to not use it at all, and that means employing NG or LPG for heating anything (cooking, clothes drying, hot water, warming house).
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  • Godsprovision
    Godsprovision Registered Users Posts: 8 ✭
    #8
    Re: solar system forming and need help

    solar_dave,

    Thank you. I will look at that. We have been changing over to CFL. Not sure I can afford to change over all of our appliances. The central air/heat would be a lot. I am looking at the mini splits as an alternative. Thank you for bringing this to my attention.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #9
    Re: solar system forming and need help
    Godsprovision wrote: »
    Not sure I can afford to change over all of our appliances. The central air/heat would be a lot.

    It will probably be cheaper to change out every inefficient load you have than to pay for a solar power system that will run them. Consider that at your current level of 32kW hours per day you would be looking at investing something around $30k-$40k for an off-grid system, about half that for grid-tie. You can buy a lot of high-efficiency appliances for that kind of money.
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  • Godsprovision
    Godsprovision Registered Users Posts: 8 ✭
    #10
    Re: solar system forming and need help
    Cariboocoot wrote: »
    It will probably be cheaper to change out every inefficient load you have than to pay for a solar power system that will run them. Consider that at your current level of 32kW hours per day you would be looking at investing something around $30k-$40k for an off-grid system, about half that for grid-tie. You can buy a lot of high-efficiency appliances for that kind of money.

    You may be right about that and that makes perfect sense to me. I would be starting with a grid tied system with the possibility of moving to off grid later.
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #11
    Re: solar system forming and need help

    If you plan to switch later on , you want to know what you will need for OG before going GT, not all pieces are able to just 'change over ' to the other side... ie you need to plan this out...
     
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