is there a "gradual" way into battery banks?

Re: is there a "gradual" way into battery banks?

Al,

Since you are in Santiago Chile, and you are trying to build an "emergency" backup system for possible 2 hour daily grid power failures--perhaps you best bet it is get the batteries first with a good inverter, with integrated transfer switch and battery charger, so the system can behave as a "giant" ups.

At this point, you don't really need solar panels as you have, I presume, reasonably priced grid power and, so far, there are no 24+ hour outages on the horizon--you just need to time shift your power because of "rolling" blackouts.

And, if you do end up with few multi-day blackouts, a fuel powered backup generator would be a cost effective method to power through a few of these vs going the whole off-grid solar option...

Since you don't use much power (4kWhrs per day or 120 kWhrs per month--congratulations on good conservation measures), one of the best small gasoline generators for the job would be a Honda eu2000i (1,600 watt inverter type). Very quiet and relatively fuel efficient even down to 25% load (fridge, freezer, a few lights and a radio/small TV). A couple gallons of gas/petrol per day would be all that is required to keep your home running (15 hours@1.1 gallons of fuel @ 400 watts, for 4 hours, 1.1 gallons, for 4 hours--basically 5+kWhrs per gallon). Yamaha and a few other off-brands of Inverter/generators are out there too if the Honda is not available or too expensive in Chile to justify.

Don't buy the very cheap 5,000 watt generators unless you are on a farm (no neighbors) and have lots of gasoline storage--these things, running small loads (like your home) are way too noisy and consume many times the fuel (with small loads) as the eu2000i. The diesel gensets are more fuel efficient--but are usually much larger than 2,000 watts and more expensive. But if you can find one that fits your needs (and does not use too much fuel at light loads)--it might be an option.

You can install all the batteries/inverter(s) you need, and a small generator for 50% of your "total costs"--and add solar panels/charge controllers as needed, and finances allow.

-Bill

PS: Conservation and choosing which loads you want electric backup power for will also reduce the loads on your battery bank... Things that need power are few (fridge, freezer, a few lights, radio). Other optional items, microwave oven, toaster, natural gas/propane powered appliances that use AC power to operate, forced air heating (unless winter) are easy to avoid during power cuts... A clothes washer does not use that much electricity (around 0.25 kWhrs per load. An electric drier would usually not be worth powering from battery).

Myself, I have a camp stove and always have some stored fuel to operate during power failures (mine emergency would probably be earthquake related in California).

In the end, off-grid solar, fuel driven generators, and such are very expensive ways to generate power... Using US numbers, those usually work out to more than $1.00 per kWhr--vs our electric costs of $0.10-$0.30 per kWhr. Even a generator is 5kWhrs per gallon--assuming $5.000 per gallon fuel is around $1.00 kWhr.