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2750w Solar Panels, I Made It...

Posted 12-12-2017 at 08:01 PM by CountryFit
Updated 05-25-2019 at 11:50 PM by CountryFit

How big is too big? In terms of solar systems, in my mind, it'll never be too big.

I started in 2013 with 5 Sunpower Grade B, 240w panels; a year later I added 4 Sunpower Grade A 240w panels. In summer time, it output a decent amount of electricity to charge my C-Max Energi, a plug-in hybrid as my toad, and the batteries. But in winter time, it's merely able to catch up with the demands from the house batteries for daily use, let alone with the toad.

The system had been good, but not "good enough" to my standard. I believed the under-performance was attributed by 5 Grade B panels. When I bought those B panels they were cheap. I measured their outputs, in the same light conditions, they were about 10% less than the Grade A panels' though both had the identical specifications.

Recently, I acquired 11 Sunpower 250w panels, model no. SPR-X20-250, premium grade, 20% efficiency, very hard to find. I measured my rooftop spaces, 11 was the maximum number of panels I could install without affecting the access to all equipment/devices on the top.

It's a painstaking job - moved down the old and brought up the new, by this one man with two ladders. I was no hurry and patiently kept it going, got it done in 2 weeks.

Now the new system looks great! At this time of the year, December, I am seeing 80A charge rate to the batteries at noon in Las Vegas; charging my toad year round may not be a problem. I am expecting 100-120A at 12v nominal downflow in summer time.


Edit on 5/5/2018
The following photos were taken on 5/2/2018 at 12:30 in a sunny day in San Jose, CA. Two solar controllers - The Midnite Classic 150 reached at its limit of 96.1a, another showed 770w (equivalent to 55a at 14.1v). Combined I got 151.1a charge rate.

Now I know that I can expect higher charge rate when summer comes that the sun is hitting the panels at nearly 90 degrees....

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  1. Old Comment
    how did you attach brackets to roof
    Posted 01-28-2018 at 08:50 PM by Reka Reka is offline
    Updated 03-26-2018 at 08:29 AM by CountryFit
  2. Old Comment
    CountryFit's Avatar
    i made the brackets out of 2" x 2" x 1/4" right angle aluminum structural and screwed them onto the roof, covered by plenty of dicor self leveling sealant.
    Posted 02-12-2018 at 08:02 PM by CountryFit CountryFit is online now
    Updated 04-11-2018 at 11:55 AM by CountryFit
  3. Old Comment

    Solar Controller

    Real nice setup, but what is the make and model of your other controller???
    Posted 05-22-2018 at 10:45 PM by beach house beach house is offline
  4. Old Comment
    CountryFit's Avatar
    beach house - sorry for the late response as i just read your question...
    the "other" controller is a non-branded chinese mppt 60a controller. being honest, i didn't expect it to last this long since 2014, and it does a good job...
    Posted 06-03-2018 at 12:10 AM by CountryFit CountryFit is online now
    Updated 05-26-2019 at 12:02 AM by CountryFit
  5. Old Comment
    Hi Steve - Finally found your blog info. Do you help out other RV Forum Members? I'm not looking for a free hand out in any way and would help a much as I can, I just wanted to know?
    Ed Rairie
    Posted 12-26-2018 at 08:45 PM by OCREF OCREF is offline
  6. Old Comment
    CountryFit's Avatar
    Thanks for visiting Ed! I am helping follow members on solar related info if I know, unfortunately I am retired and unable to provide physical assistance on install and set up. Regards.
    Posted 12-26-2018 at 09:21 PM by CountryFit CountryFit is online now
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