Newbie ready to go off grid

I would also look at the value of the property with and without utility power... More or less, i would guess that $35k will increase the value of your property by ~$35k... Spend $20k-$40k on solar--more than likely, it will add little to the value of the property (especially 10-20 years out, or whenever you end up too old to manage the property and systems).

More or less, a "medium" size off grid power system that is able to give you a new normal electrical existence is around 100-300 kWH per month. In California that is ~$10 per month connection charge and ~$25 to $75 per month usage charge.

Say you want a 100 kWH pwer month system (~3.3 kWH per day). That is about 1/5 to 1/10 the amount of electricity the "typical" north American home uses (~500-1,000 kWH per month). You can run a full size refrigerator, LED lighting, Laptop computer, well pump, washing machine. Use other fuel for hot water/space heating.

Lets assume flooded cell batteries, 48 VDC bus, 2 days of storage and 50% maximum discharge (seems to be optimum costs and for longer battery life):

• 3,300 WH per day * 1/0.85 inverter eff * 1/48 vdc battery * 2 days storage * 1/0.50 max discharge = 324 AH @ 48 volts

Or, roughly, 8x 6 volt golf cart batteries (~200 AH) * 2 parallel strings would give you ~400 AH @ 48 volts (16x GC batteries total). Golf Cart batteries are a nice start--They are cheap and fairly rugged. And many people "murder" their first battery bank or two as they lean to manage their off grid power systems.

For calculating the solar array, two methods. One is based on the size of the battery bank (larger battery banks need higher charging current to "be happy"). The second is based on hours of sun and protected energy usage. For flooded cell lead acid batteries, suggest ~5% to 13% rate of charge as a start. 10%+ is recommended for a full time off grid home (can get away with 5% if weekend/summer cabin). I will use the 400 AH GC battery bank as a good fit for a smaller system:

• 400 AH * 59 volts charging * 1/0.77 solar panel+controller deratings * 0.05 rate of charge = 1,532 Watt array minimum
  
• 400 AH * 59 volts charging * 1/0.77 solar panel+controller deratings * 0.10 rate of charge = 3,065 Watt array nominal
  
• 400 AH * 59 volts charging * 1/0.77 solar panel+controller deratings * 0.13 rate of charge = 3,984 Watt array typical "cost effective" maximum
  

Using PV Watts for Lancaster PA, fixed array at 50 degrees from vertical, will give you "hours of sun" per day by season:
http://www.solarelectricityhandbook.com/solar-irradiance.html

Lancaster
Average Solar Insolation figures

Measured in kWh/m2/day onto a solar panel set at a 50° angle from vertical:
(For best year-round performance)

Jan	Feb	Mar	Apr	May	Jun
3.04	3.72	4.16	4.37	4.71	4.82
Jul	Aug	Sep	Oct	Nov	Dec
4.95	4.73	4.54	4.14	3.02	2.67

A 3.3 kWH system that will run from solar ~9 months of the year (use backup genset for dark winter stretches):

• 3,300 WH per day * 1/0.52 off grid system eff * 1/3.72 hours of sun (February "beak even" month) = 1,706 Watt array
  

So, the nominal solar array for your installation would be ~1,706 Watts to ~3,984 Watt array. A good mid point would be #,065 Watt array which would give you (in February) around

• 3,065 Watt array * 0.52 solar system eff * 3.72 hours of sun (Feb) =  5,929 WH ~ 5.9 kWH per day

A 400 AH @ 48 volt battery bank will carry you for two days of "no sun" (before running backup genset):

• 400 AH * 48 volts * 0.85 AC inverter eff * 1/2 days storage * 0.50 max discharge = 4,080 WH ~4.08 kWH per day of storage (for 2 days of no sun)
  

With a 400 AH @ 48 VDC battery bank, around a 2,000-4,000 Watt AC inverter would be a good fit.

Get an "off grid" power friendly well pump (not cheap, but they do not "surge" when starting--Something like 900 Watts maximum vs 2-4+ kWatts for standard AC well pump). Possibly pump to cistern and use a smaller DC (or AC) pump for water pressure works nice.

If you decide that you want more energy than 100 kWH per month (3.3 kWH per day), just multiply the above calculations by 2-3x for a moderate size system.

Price it out and include maintenance costs... Batteries will last ~3-5 years (if "cheap" golf cart"). ~7 years for typical mid range batteries. or ~15+ years for higher end fork lift batteries. And, if somebody leaves the lights+TV+fan+etc. on (kids drop by), you can kill a battery bank in a few days or weeks (or if something fails, like charge controller, miss programming something, etc.).

Your AC inverter and solar charge controller (backup AC charger, etc.)--Assume that you will have to replace them every 10+ years.

Not trying to stop you from using solar--But $35k + less than a $100 per month power bill (what will be your electric charges?) is not bad. Plus, add a backup genset and 5-14 days of onsite backup fuel (propane is nice, diesel if you have diesel heating, car/truck, etc. can work out). Or even a small Honda eu2000i (1,600 watt) AC genset + 30 gallons of backup fuel + fuel stabilizer (run the old fuel through your vehicles once a year)--Very nice if deep rural area where it can take days/weeks to restore power after a major storm.

You can go with DC appliances (fridge/freezer/pumps, etc.)--But many times, the modern Energy Star AC models are just about as efficient and 1/2 to 1/4 the retail price of the DC off grid equivalent.

Your thoughts?

-Bill

Energy usage is a highly personal set of choices. What works for me or you--May or may not work for our friend here.

I try for education so that everyone can make informed choices.

An interesting read is the Home Power Magazine. They have a fair number of articles online to give you some ideas.

https://www.homepower.com/

While I usually try not to be wasteful of energy usage (aka--I am cheap), there are downsides to extreme conservation too (poor air circulation in "sealed homes", issues with mold, scalding hot water from solar water heating, etc.). Doing research before building your outpost will save you from quite a few expensive mistakes.

-Bill