Where to start ? Newbie Question

System
System Posts: 2,511 admin
In a very few years I plan to retire in Northern Idaho, near Saint Maries. We will be living a rural setting, but will have power, phone, but that's about all. Water will come from a well. Heat will be propane (maybe). If possible, I'd like to completely produce enough power to avoid any electrical utility bill.

I'm interested in evaluating the possible use of solar electric power in my retirement home (not rest home). If I understand the basics, I need to do the following to have a fundamental understanding of the opportunity.

A) I need to understand what my electrical power use will be in the new
home, based on appliances, etc.
B) I needed to understand what the cost of the electric power, when
purchased from the local utility.
C) I needed to understand the potent average energy from the sun for that
location in kilowatts per meter per furlong per calorie in a lunar cycle (i.e.
some unique unit of measure)
D) I then need to determine the number of solar panels that would be required
to produce the necessary power for the new home, based on the potental
average energy from the sun in Saint Maries.
E) From that number, I can determine the basic cost of the panels and
mounting hardware. (This will require that I have some understanding of
efficiencies, etc.)
F) Assuming that I will remain tied to the grid; I will then need to determine
the cost of the necessary DC to AC converter/synchronizer, based on the
power generated by the panels.
G) I will also need to determine the cost of a power meter that monitors the
power that I am providing to the grid.
H) Then I need to determine the cost of point to point wiring, junction boxes,
circuit breakers, conduit, disconnect switches, etc.

Hopefully, by now I have a estimate of the basic material cost. Then I have to determine labor cost, cost of building permits, inspection fees, etc.

Once this is done, I can then calculate the point in time when I "break even" on the expense.

Did I cover the basic ? It is easier and perhaps more cost effective to use a good contractor (if one can be found) ? Is there a good book that I can read that will help me ensure that I've done all of my homework?

Thanks for putting together this forum. It's a great source of information.

Regards,
tucker1

Comments

  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Where to start ? Newbie Question

    Read all you can, on this site and others. Consider Home Power Magazine. Avoid the ready, fire, aim.

    Good luck,

    Tony
  • BB.
    BB. Super Moderators, Administrators Posts: 33,404 admin
    Re: Where to start ? Newbie Question

    Tucker,
    Tucker1 wrote: »
    ...Northern Idaho, near Saint Maries. We...have power...Water will come from a well. Heat will be propane (maybe). ...I'd like to...electrical utility bill.

    A) I need to understand what my electrical power use will be in the new
    home, based on appliances, etc.

    Yes! And you need to conserve as much as possible (insulation, energy star appliances, turn things off, etc.).

    You need to know in kWattHours (kilo-Watt*Hours or Watt*Hours... A 100 watt bulb * 10 hours of running = 1,000 Watt*Hours = 1 kWhr). Conservation would be replacing the 100 watt bulb * 10 hours with a 13 watt bulb * 10 hours = 130 WattHours.

    If you were off grid, then you would also need to know the peak energy usage--for example your well pump may need 2,000-3,000 watts--but only for a few tens of minutes a day. Very high usage for a short time (large inverter, less battery/solar panels required). For Grid Tied, just your monthly/yearly electrical usage.
    B) I needed to understand what the cost of the electric power, when purchased from the local utility.
    Electric power costs are around $0.10 per kWhr for non-east/west coast states. And for high usage in East/West coast states, upwards of $0.35 per kWhr (or more).... Shows you where you power costs can easily go to in the next few years.

    Also, there are Time of Use rate plans... Pay more for power during the day/early evening. Pay less for night. Can help with grid tied solar systems--you get paid more money per kWhr during day, and use the cheaper power at night (my summer noon-6pm rate is $0.27 per kWhr, my off-peak rate is $0.09 per kWhr--making my solar panels "three times bigger" rate wise). However, if you cannot shift to off peak times, then Time of Use plans may hurt you instead (pay more, rather than less).
    C) I needed to understand the potent average energy from the sun for that location in kilowatts per meter per furlong per calorie in a lunar cycle (i.e. some unique unit of measure)
    The sun peak/averages around 1,000 Watts (1kW) per square meter. So, solar panels are rated at 1kW/sqm. In round terms, it is easier to talk about "hours of sun". Your area may get "6 hours of sun" during the summer, and 2 hours during the winter... Meaning that you will get 3x as much power from your panels in the summer vs winter.

    But with the handy government web site--you can calculate your energy from your solar panels directly without going through all of the conversions.
    D) I then need to determine the number of solar panels that would be required to produce the necessary power for the new home, based on the potential average energy from the sun in Saint Maries.
    So, here are two handy places to look. One gives a PDF file for your state--and is much easier to read and understand the variables (fixed, tracking, winter/summer, and year over year variations). The other site--you plug in some numbers, and it gives you the "average" production from your system--quite accurate from my experience vs my system.

    Since you have asked for a grid tied system (not off-grid with batteries), which is the most cost efficient--using the second website and all numbers as default. 1kW of solar panels in Spokane WA (closest to your location?) will give you 1,181 kWhrs of electricity per year.

    Assuming you have 1 year net metering from your electric company (they add up all of the power you generate minus all the power you used over 12 months--if your generate=used, you don't pay anything other than a few dollars per month for the meter/minimum power bill), and you, for example, use 600 kWhrs per month or 7,200 kWhrs per year, then you would need:

    7,200kWhrsperyear/1,181kWhr per year per 1kW of panels = 6.1 kWatts of solar panels.

    Roughly, that would be a 5.2 kW rated solar system (in terms of rebates).
    E) From that number, I can determine the basic cost of the panels and mounting hardware. (This will require that I have some understanding of efficiencies, etc.)
    A turn key system will cost you, roughly $5 per watt for solar panels, $1 a watt for mounting, $0.50 per watt for a grid tie inverter, and $2 per watt for turnkey installation, wiring, and permits. Or, very roughly around $8.50 to $10.00 per watt for a full turnkey system (based on 5,200 watt system rating). Or $44,000 to $52,000 (very rough numbers--SWAG).
    F) Assuming that I will remain tied to the grid; I will then need to determine the cost of the necessary DC to AC converter/synchronizer, based on the power generated by the panels.
    Grid Tied is the best bang for the buck in terms of reliable solar energy... Remember that Grid Tied solar does not give you emergency back power--your utility line fails, you have no electricity. There are other hybrid and off-grid systems which can give you long term backup/off grid power--but they will triple (or more) your cost for electricity.

    If your power is reliable, a small generator just to power your minimum loads is a more cost effective way to go... If you have long runs of no power (say ice storms, heat waves), then a hybrid Grid Tied / Off Grid system may be worth the added costs to you.

    Also, if you have snow in your area--you should mount the panels higher off the ground (allow snow to slide off), and if you can tilt them towards vertical during the winter, it will help shed snow, and you will gain more power during the winter from the low sun and reflection off of the snow.
    G) I will also need to determine the cost of a power meter that monitors the power that I am providing to the grid.
    Should not be much.... My TOU (Time of Use) meter cost $277 and my monthly minimum charge is less than $6. Yours may be different.
    H) Then I need to determine the cost of point to point wiring, junction boxes, circuit breakers, conduit, disconnect switches, etc.
    Should not be a huge cost if you have modern 125-200+ amp service and the solar panels are close to your home/breaker panel. If not--well an electrician would have to give you a quote.
    Hopefully, by now I have a estimate of the basic material cost. Then I have to determine labor cost, cost of building permits, inspection fees, etc.

    Once this is done, I can then calculate the point in time when I "break even" on the expense.
    Very simple cost of power:

    $44,000 for system / (7,200 kWhrs per year * 20 years) = $0.31 per kWhrs

    Assuming no property taxes, loan interest, and nothing breaks (your Grid Tied inverter may not last 20 years--so you might need to buy a replacement 1 time--good quality mono/poly crystalline solar panels should easily last 25+ years).

    What is the cost per kWhr for your power (Idaho is listed in the program as $0.061 per kWhr).
    Did I cover the basic ? It is easier and perhaps more cost effective to use a good contractor (if one can be found) ? Is there a good book that I can read that will help me ensure that I've done all of my homework?
    Don't know of a good book, but Home Power Magazine would be an interesting read for you...

    By the way, for rebates/tax credit information, and details on solar laws/programs for your state, see this site. Idaho seems to offer some programs/tax breaks.

    Also, regarding heating... Solar Thermal heating (domestic hot water, domestic heating, etc.) can offer you better return on your money than solar electric... And, in the end, if you save more money on propane vs electricity--it is still money saved.

    The down side with solar thermal is that it requires more maintenance (water, antifreeze, leaking tanks, pumps that go bad, etc.) and there are issues with freezing climates (antifreeze/drain back systems, etc.)... I went solar electric because there is zero maintenance over the life of the system (plus I did not trust California with my electric rates).

    Check out SolarRoofs.com for hot water systems geared towards self installation.

    Hope this helps.

    -Bill

    PS: Regarding system monitoring... Most Grid Tied inverters (and most good quality solar charge controllers) include a simple panel meter where you can take daily/monthly readings to check your power generation. Take the reading on the same day your meter is read, and you can simple subtract one from the other to understand your power patterns.

    Xantrex has a very simple RS 232 interface for their GT systems... And there are a couple free programs out there that run an old PC if you want more data (or to dump on the web)... Other companies will over various options for monitoring--and may cost you a few hundred dollars (or a bit more)...
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset