small system for charging phones and other small items?

Ron_in_NC

Very new to solar, would love to put a huge array on our house in central North Carolina (Durham) but we're surrounded by large trees and the house doesn't even face the right way (roughly east-west facing roof facets with the east side well blocked by a large oak). So scaling down to what might be possible. I think I have room for 4 panels or so that would get reliable mid-day and afternoon sun over the garage. Any suggestions for a simple system that I could set up to charge our phones and other devices inside the house? Family of 5, we charge phones most nights and misc other devices on occasion. Would feel good to run those all off solar power.  Should I just get a Goal Zero type device and run a line into the house to charge it?

BB.

There are apps for phones that can do a better job of estimating "hours of sun per day" (i.e., 3+ hours of "noon time equivalent" sun per day is, at least, is "decent sun"). Using a "simple" solar harvest estimating link:

http://www.solarelectricityhandbook.com/solar-irradiance.html

Durham (East or West facing array)
Average Solar Insolation figures

Measured in kWh/m2/day onto a solar panel set at a 54° angle from vertical:
(For best year-round performance)

Jan	Feb	Mar	Apr	May	Jun
2.86	3.18	3.85	4.03	4.18	4.13
Jul	Aug	Sep	Oct	Nov	Dec
4.08	3.89	3.88	3.85	3.10	2.80

Durham (South facing)
Average Solar Insolation figures

Measured in kWh/m2/day onto a solar panel set at a 54° angle from vertical:
(For best year-round performance)

Jan	Feb	Mar	Apr	May	Jun
3.58	3.97	4.81	5.04	5.23	5.16
Jul	Aug	Sep	Oct	Nov	Dec
5.10	4.86	4.85	4.81	3.87	3.50

On an East or west facing array, assuming 1,000 Watts of panels in December, blocked 1/2 the day:

• 1,000 Watts * 0.52 off grid AC system eff * 1/2 blocked by trees * 2.80 hours of sun E/W = 728 WH per day
• 1,000 Watts * 0.52 off grid AC system eff in full sun * 3.50 hours of sun E/W = 1,820 WH per day

Just an example of how to estimate your harvest for an average December day with 1/2 of sun vs the "ideal" south facing/no tree harvest.

Some days will be more, some will be less...

You can use a Kill-a-Watt meter to estimate the energy usage of your AC appliances:

https://www.amazon.com/kill-a-watt-meter/s?k=kill-a-watt+meter

For USB devices, you can get USB Watt*Hour meters:

https://www.amazon.com/s?k=usb+power+meter&sprefix=usb+power+meter

And generic DC power meters:

https://www.amazon.com/s?k=DC+power+meter&crid=1H4YE57TIL5BD&sprefix=dc+power+meter

Gives you some ideas of what the math looks like... And meters that can measure your daily energy needs before you start spending $$$ for solar.

And there are options, especially if you are looking at larger solar power systems. The larger systems, you can install the panels/arrays 100's of feet from your home and run the wiring back to the charger/power system at higher voltages (100 VDC to 400 VDC).

Or if you are just looking at saving money, you can run Grid Tied Inverter(s) and connect that to your AC main panel (solar panels -> GT inverter(s) -> main panel). These can save you money (need to review your utility's rate plans). But they will not give you emergency backup power (unless you design a battery backed system)....

Depending on your energy/system needs, the answers can vary. GT solar can give your "cheaper" solar power (and save you money on your power bill). Off grid/Hybrid solar power systems (+Battery banks)--Are generally not cheap (looking at $1 to $2+ per kWH--First pass guess).

-Bill

Ron_in_NC

Thanks Bill! Sadly not any room for an array off the house either, we're on a suburban lot with a swamp behind us. Lots of trees! Good leads on measuring usage, that would help me get a better idea of what size. At this point I don't aspire to run any AC appliances, I just don't think we have the sun for it. But recharging 5 smart phones every night plus cameras, etc now and then, that seems possible.

BB.

Ron,

One of the things you have to watch for... Trees grow and today's sort of useful sun could be "gone" 5-10 years down the road if you cannot "maintain" the trees (and the expense of arborist/trimming--And in our location, the city likes to have a say too).

-Bill

garynappi

Hi Ron, my house has a similar east / west roof orientation, added to that my roof is barrel tiled and I did not want to crash through them to mount solar panels. 

I solved the issue for low powered DC devices by mounting my panels and charge controller (CC) on a south facing wall which is mostly unobstructed. 

My mistake(s) were going too small with the panel wattage and not anticipating the expansion my curious mind eventually wound up fleshing out. Even so my modest system wound up with LED yard perimeter lighting, yard charging station with DC fans under my mango tree, gable attic fans for house venting (they work GR8) and two water fountains. 

The issue(s) you may need to think about is charging at night. If they are close to the house, you could easily run a cable from your batteries at night and gen up a DC powered USB charging station. 

Then depending on how many devices you want to charge you may need to scale it up from something like the second pic I supplied. Of course if your mind is curious like mine, an indoor LED USB table lamp would come in handy as a night light, as would an outdoor wall mounted LED spotlight connected to your CC's load. In case you lose power. Oh, Malibu lighting is also cool as is, the... See how I think?