A good start--Plan on 1,000 WH per day... Run LED lights, RV water pump, laptop computer, cell phone charger... Say you run the "stuff" for 5 hours in the evening (assume a 8 amps @ 12 volt or 4 amp @ 24 volt RV water pump--Not really much energy for 20 minutes of water per day)... Then the average available watt*hour or amp*hours per day would be (even 500 Watt*Hour per day system might even be fine if just lighting and cell phone charging plus some other random stuff):

• 1,000 WH per day / 5 hours per day usage = 200 Watts average load (for 5 hours)
• 1,000 WH per day * 1/12 VDC * 1/5 hours = 16.7 Amps average load (for 5 hours)

Just taking a basic rule of thumb design... 2 days of storage, 50% max discharge:

• 1,000 WH per day * 1/0.85 AC inverter eff * 2 days storage * 1/0.50 max planned discharge * 1/12 volt battery bus = 392 AH @ 12 volt battery bank

That would be 2x 200 AH @ 6 volt Golf Cart batteries in series * 2 parallel strings for 4x GC batteries total (around $400 worth).

To charge that--5% rate of charge for sunny weather use (possible genset backup charging). 10% suggested minimum for full time off grid--And 13% typical "cost effective maximum charging rate:

• 392 AH * 14.5 VDC charging * 1/0.77 panel+controller deratings * 0.05 rate of charge = 369 Watt array minimum
• 392 AH * 14.5 VDC charging * 1/0.77 panel+controller deratings * 0.10 rate of charge = 738 Watt array nominal
• 392 AH * 14.5 VDC charging * 1/0.77 panel+controller deratings * 0.13 rate of charge = 960 Watt array "typical" cost effective maximum

And then there is the array based on your daily loads and average sun. Fixed array facing south for Candem NY (zip 13316 seems to work better:
(Wrong link--good/simple solar calculator) http://www.solarelectricityhandbook.com/solar-irradiance.html
This is based on a 1,000 Watt array (minimum for PV Watts), 43 degree tilt from horizontal, and 48% losses (52% off grid AC battery system overall efficiency):

RESULTS

System output may range from 706 to 746 kWh per year near this location.
Click HERE for more information.

Month	Solar Radiation ( kWh / m2 / day )	AC Energy ( kWh ave per month )	Value ( $ )
January	2.84	45	5
February	3.72	54	6
March	4.66	70	8
April	5.24	72	8
May	5.41	74	9
June	5.33	70	8
July	5.82	77	9
August	5.62	76	9
September	5.31	71	8
October	3.80	54	6
November	2.86	41	5
December	2.09	33	4
Annual	4.39	737	$ 85

Say you use the system from February through October--Or a minimum of 3.72 hours of sun average (Feb):

• 1,000 WH per day * 1/0.52 off grid AC system eff * 1/3.72 hours of sun = 517 Watt array February "break even" size

Just to give you a quick way to figure out what size MPPT solar charge controller (Amps @ XX volts)--Here is "minimum" Ampere rated MPPT solar charge controller suggested (assuming a 77% panel and controller derating):

• 738 Watt array (10% rate of charge) * 0.77 array+controller derating * 1/14.5 volts charging = 39 Amp minimum rated MPPT solar charge controller

So--That gives you enough power to run stuff in the evening (quiet time, some 12 VDC or 120 VAC lighting for late night usage)... And use the genset(s) when you need more power during the day.

A 300 Watt 120 VAC TSW/PSW inverter @ 12 VDC input--This is a good one to take a look at. Includes "sleep mode" and remote on/off:

https://www.solar-electric.com/morningstar-si-300-115v-ul-inverter.html

Inverters "waste power" just being turned on (Tare Losses)... It is 6 Watts for this one, and in sleep mode less--And a remote on/off switch to save even more power...

You have the choice of taking the batteries home during the winter--Or (for example) get 1% to 2% array to float charge the battery bank over winter (with a simple/small charge controller and the panel(s) mounted on a vertical surface to limit snow sticking to panel through winter).

• 392 AH * 14.5 volts * 1/0.77 panel+controller losses * 0.01 rate of charge = 44 Watt minimum suggested float panel
• 392 AH * 14.5 volts * 1/0.77 panel+controller losses * 0.02 rate of charge = 88 Watt max needed float panel

Fully charged FLA batteries are pretty "happy" at freezing and well below temperatures--As long as they are kept charged. And sub freezing batteries have much slower self discharge--So a small "float array" is usually "good enough" to keep the batteries fully charged (even if panel is covered with snow for a month or two). Make sure all other loads are turned off (including a larger MPPT type charge controller--If you have enough sticky snow to cover the panels for weeks/months at a time otherwise--Even a few Watts of loads can slowly discharge the battery bank if no charging current is available).

Nothing above is written in stone... But it does give you a good target for your initial paper design. And a very capable solar power system.

There are lots of chargers, inverters, inverter-chargers, AC chargers, etc. available... You can look through our host's website, and other places, and see what prices/performance/options look good for you.

Do not plan on taking a small system and adding too it... Most of the hardware will need changing (AC inverters are dedicated to one bus voltage--Larger solar arrays need larger charge controllers, and a simple GC Battery bank will last around 3-5 years of normal usage with good maintenance and charging regime. Some people move the "small system" to a guest building or shed--Or you may be able to reuse the solar panels (it can be difficult to even mix/match solar panels into a larger array).

And there is always the chance that things will "walk" when you are not there... You probably don't want to leave a very expensive system onsite when you are not there.

Your appliance energy usage chart is around 33,000 WH per day or 1,0000,000 WH per month (or 1,000 kWH per month on your utility bill)... While that is certainly "doable" for off grid power--That is a pretty big system. A standard North American home uses around 500 to 1,000 kWH.

For a first power system that is of "reasonable" size... Try to live in the 3,300 WH (3.3 kWH) per day or ~100,000 WH (100 kWH) per month usage... That is about enough power to have a "near normal" electrical off grid life (albeit with lots of conservation, using alternative fuels like wood, propane, etc. for heating/cooking/hot water).

-Bill