More Solar for "Us"

[MrWizard]

Ok, I went off.the deep end?
Bought 3 used 37watt uni-solar panels and a blue sky 2000e controller for the hefty price of $400,
They were being listed as 75w panels, they are not

The tested open circuit voltage was 21+, short circuit amps 2.9
I tested each panel multiple times tilted into the sun and laying flat on the ground , got the same readings each way, that was the deciding factor, they appear to put out full power while laying flat, I will try to mount them tomorrow before it gets hot, right now 104°F
I will use the existing wiring until I buy & install the new wire

[MrWizard]

location and climate , time of year occupied ?

Don's estimates trend toward off grid solar home type use in far northern climate
our residential fridge is our largest power use ,followed by lighting

where we are
if we had a lp fridge the 300+ watts
on the roof would.cover most of our
use

the mw & coffee maker would still need the generator

not enough solar to recover the deep power drain from those items

to go without generator recharge using our residential fridge we need about 600watts of solar and eight batteries
I have the extra four batteries waiting for me to build the slide for them,
I don't have the extra solar

your power needs will be different

[pianotuna]

Hi MrMudstud,

That depends on what you want to run, and the time of year, so start with an energy audit.

If I avoid the use of my inverter and run my fridge on propane, I have more than enough to run my twelve volt side for probably 8 months of the year.

If you truly want to eliminate generator run time, the battery bank needs to be good for ten days total use. Some frugal RV's use about 50 amp-hours per day. That suggests a battery bank of 1000 amp-hours to keep above the 50% state of charge mark. To keep such a bank in good shape, solar wattage needs to between 600 and 1500 watts. Six hundred watts is quite possible but for 1500 watts there may not be enough "real estate" on the roof.

Costs for a 600 watt system run under $3.00 per watt for parts.

[MrMudstud]

MrWizard........If you had to guess/figure how big a solar panel watts would be needed to be self sufficient, what would the majic number be.........Thanks

[pianotuna]

Hi Mr. Wizard,

Thanks for the information.

That long term generator gasoline costs should prove interesting in the next year or so.

[MrWizard]

no spread sheets
no running total of energy
just watching for trends and daily increase or decrease
my total daily energy consumption is 2 > 3 times the avg daily solar input, so I'm still using my generator
I won't claim that solar has cut my generator fuel costs 33% , but it has made a recognizable reduction, I'm not calculating fuel costs, but I do record my generator gasoline costs

if we didn't have the electric fridge, I think the 321w of solar would cover 90% of my energy use, the inverter circuit fridge & residential lighting , TV etc.. is 90% or more of our electrical use

[pianotuna]

Hi Mr. Wizard,

Are you keeping a "running total" for the amount of energy gathered "for free"? I'm wondering how long it will be before the break even point on the cost of the solar panels etc is reached, in saved generator run time.

[MrWizard]

Thursday Jan 27
errands & doctors visits
very little generator time, mainly solar charging
totals
64.71 amphrs
878.1 watthrs
11.84 peak amps
148.4 peak watts

generator charging done after dusk during super hour

[bigfootford]

MrWizard wrote:
saturdays reading

58.32 AHRS
816.1 Whrs
10.42 peak amps
144.5 peak watts

Gotta love it!!!

Jim

[MrWizard]

saturdays reading

58.32 AHRS
816.1 Whrs
10.42 peak amps
144.5 peak watts

[MrWizard]

not to bad today, real sunny lots of wind

55.34 amphrs
756.2 watthrs
11.2 amps peak
149.7 peak watts

Jan 1st a few clouds was

48.01 amphrs
670.0 watt hrs
9.96 peak amps
139.4 peak watts

[mena661]

vcallaway wrote:
I think those suntech's have been discontinued. Can you post a link for someone that still has them for sale at that price?

Sure. Suntech 175W

[pianotuna]

Hi vcallaway,

There are lots of panels here:

low cost panels

vcallaway wrote:
I think those suntech's have been discontinued. Can you post a link for someone that still has them for sale at that price?

[MrWizard]

the two for $500 is long gone
looks like the current special is a 100w "solar cenergy" panel for $259

[vcallaway]

I think those suntech's have been discontinued. Can you post a link for someone that still has them for sale at that price?

[MrWizard]

overcast gloomy weather around 20+ amphrs (as high as 26 )
actual rainy days as little as 11amphrs

there were days in early Nov 60+ amp hrs
days in Oct over 70 amphrs

enough to provide for the fridge for 24 hrs

my hope is that during spring and early summer when I don't need to park in the shade and run the A/C there will be enough power to run the fridge and charge the batteries so I can eliminate the generator on a few days
right now the solar is mainly doing "top off" duty, after I run the generator in the morning for coffee and recharge, the solar keeps the batteries topped off so they are still full at sun down, which happens before super, I run the.generator for an hr at super, then everything is on battery power until the next morning