Ivor O’Connor

December 13, 2009

Lowes, Akeena, Enphase: DIY Solar Panels

Filed under: Clean Renewable Energy, green, Solar PV Panels — Tags: , , , — ioconnor @ 6:46 pm

This week Lowes started selling DIY solar panels at 21 locations in California. Each panel can plug directly into a 120V household socket thanks to Akeena integrating in Enphase inverters. However things need to be installed properly. So to assure warranties, safety, and maximum tax rebates Lowes now has help desks at each of these 21 stores to get you through all the steps.

So I’m thinking the price tag, $893 or 625 after fed tax rebate, can be cut down to something reasonable with tax rebates. Then compare the costs to the various price tiers Southern California Edison charges to figure out how economical this solution really is. Maybe it would only be economical to buy enough to keep the electrical bill from reaching a particular tier. So the first steps are to get the tier pricing, the past electric bills, and to locate one of these Lowes stores and pay them a visit to get more details.

So what I want to learn:

  1. SCE tier pricing.
    I’m assuming the panel costs $625 and produces 112 watts at an average of 5.5 hours a day for the following calculations:
    Tier 1: $.12 <100% (Less than 24 year payoff = 2.9% annual return)
    Tier 2: $.14 <130% (Less than 20 year payoff = 3.5% annual return)
    Tier 3: $.23 <200% (Less than 13 year payoff = 5.4% annual return)
    Tier 4: $.27 <300% (Less than 11 year payoff = 6.5% annual return)
    Tier 5: $.30 <400% (Less than 10 year payoff = 7.1% annual return)
  2. Bills for the last year or more
    This months bill comes out to about $0.16/kwh or a 4.4% annual return.
  3. Location of Lowes selling solar panels
    The local Lowes store has no idea, they’ll call me back tomorrow after talking with corporate.
    A day has passed and they never called back. Big surprise. I’ll call them again later this week.
  4. Determine expected tax rebates.
  5. Determine exact components.
    1. Enphase power converter w/15 year warranty instead of 25 year warranty like the rest of the product. Then there is a 119 year mean time between failure claim here http://www.enphaseenergy.com/products/moreinfo/howitworks.cfm. (Don’t circuits go bad in 40 to 50 years?)
    2. Enphase Enlighten software? The software doesn’t seem to be much more than fluff. http://www.enphaseenergy.com/products/moreinfo/enlighten.cfm. Can the data be downloaded automatically so something more serious can be done with the data. Do they allow the software to be viewed using somebody elses panels? Do they charge for this software?
  6. Determine warranties
    Will probably be 25 years with qualifications and the Enphase inverter might be something much less…
  7. Enphase Enlighten
  8. Put it all together?

What I currently know:

  1. $625 after federal tax rebates
  2. 175 watts per panel
  3. 7.1 hours max sunlight during summer in southern California
  4. 3.9 hours max sunlight during winter in southern California
  5. 7 percent loss due to soiling
  6. 12 percent loss due to heating
  7. 5 percent loss due to wiring
  8. 6 percent loss due to inverter
  9. 20% drop off at some point in time is acceptable probably
  10. With all the losses the 175 watts will come to only 112 watts…

What I think I know:

  1. I could put 13 panels on one 20 amp circuit. Probably should only put 10 on for safety.
  2. A laptop uses about 100 watts with a large external display. So I’d need about 5 panels in winter to run one laptop 24×7. Or 20 panels to run 4 laptops. Printers, faxes, routers and such would probably take another 5 to 10 panels. So I’m probably looking at 30 solar panels on three circuits.



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