4 responses to How many solar panels do I need for my house? Power company says I used 20 Kwh per month.?

• scott

  Comment on How many solar panels do I need for my house? Power company says I used 20 Kwh per month.? (February 13th, 2010 at 00:12)

  20kwh = 3 dollars and forty cents. Check your electric bill and it will tell you how many you really use. You probably use 20kwh per day that would make your bill around 100 bucks a month.
  References :

• Fixit

  Comment on How many solar panels do I need for my house? Power company says I used 20 Kwh per month.? (February 13th, 2010 at 00:53)

  One panel should be sufficient if your systems is set up correctly. However, the panels are usually 4×10. If you are going to DIY, please let me know. I have plans for a DIY solar collector. I am going to be selling them in Central Florida
  References :

• Amy

  Comment on How many solar panels do I need for my house? Power company says I used 20 Kwh per month.? (February 13th, 2010 at 01:18)

  Double check your electric bill, if you have a fridge, there is no way that is correct. A fridge would use around 60kwh / month. Once you are sure of your actual monthly usage, put it in a calculator like this http://www.altestore.com/store/calculators/on_grid_calculator/ to determine how many watts you need.

  If 20kwh/month is correct, you’d only need one solar panel and a micro inverter. http://www.altestore.com/store/Solar-Panels/150-Watts-Up-Solar-Panels/SolarWorld-SW175-175W-24V-Solar-Panel/p6107/ and http://www.altestore.com/store/Inverters/Grid-Tie-Inverters-On-Grid/2000W-and-Under/Enphase-Energy-Micro-Inverter-190W-208VAC-MC4/p7303/
  References :
  AltE Store – http://www.altestore.com/store/

• Solarmandan

  Comment on How many solar panels do I need for my house? Power company says I used 20 Kwh per month.? (February 13th, 2010 at 01:35)

  I’m going to assume a couple of factors here;
  1. That your electric kw consumption is probably closer to 20 kWh a day rather than 20 kWh a month.
  2. Thar you will be using pre manufactured solar panels which are a lot closer to 3ft by 5ft in size and produce around 220w ea.

  Here’s the formula;
  1. Go to www.pvwatts ver1 and get the average available sun hrs for your area ( where I live in no California this is around 5.5 hrs a day).
  2.Add your kWh consumption for1yr (from 12 utility bills) and then divide that total by 365 (days of the year). This will give you your daily kWh consumption.
  3. Divide your daily kWh total by your daily average sun. This will give you your D/C system size.
  4. Divide your D/C system size by .77 (derating factor) and you will have your total size needed.
  5. Divide your total from line 4 by the number of watts per panel to get the quantity of panels needed.

  EXAMPLE: 20kWh (daily use) divided by 5.5 ( average daily sun hrs) = 3.64kw (D/C system size)
  3.64kw divided by .77(derating factor) = 4.72 (actual system size needed)
  4.72( system size) divided by 220 (watts per panel) = 21 panels needed
  Hope this helps. feel free to post any further questions at http://www.solarmandan.com
  References :
  www.solarmandan.com

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