What I can tell you right now is that ain't gonna happen! There is no more expensive why to generate electricity than with off-grid solar. If you want off-grid solar because you are planning for emergencies, then great. But do NOT expect in any way whatsoever that off-grid will ever save you money.2- Big or burst, buying 6 to 10 370-400 watts solar panels, 800-1400 Ah of batteries and hooking the whole thing to the grid in a way that it can works everyday and save me money from my electricity bill but also being able to disconnect it from the grid in emergencies and works powering 70-80% of my normal electricity needs backed up by the generator.
Thanks Hedges, i will have to study the whole thing and research prices a little bit more. Seeing that i want to mount the solar panels on the floor, (so to be able to dismount them and getting them secure in case of a hurricane) i only got space (sun oriented) for like 10 of them, got a lot of cypress trees in my property.Before you buy panels, select the inverter they will work with and plan how the panels will be connected (series & parallel) to fit the voltage and current requirements of the inverter. Maybe you want 8 (4s2p), maybe 9 (3s3p) or some other optimum arrangement. Then buy a spare or two in case you break one. Shipping is more expensive than a panel.
"8, 370W panels" sounds like $1300 to me:
https://store.santansolar.com/product-category/solar-panels/
Grid tie net metering may still be advantageous. It depends on how much the utility has messed up rates to shift it in their favor. It is possible to install solar power, reduce your consumption, and have your bill go up. You need to understand what new rates (and time of use schedule) will be imposed.
I think I can install a 5000W PV system for about $5000. That does take me quite a few hours work. I don't know what prices you can find for someone else installing.
There are some brands of inverters which support grid-tie net metering and battery backup. I think SolArk is one several people here have used. Member SolarQueen who works for Alt Energy Store does designs for people, and can sell you complete plans if you need that for permitting.
There are some alternatives, inverters that do grid-tie and batteryless backup. Not sure, but SolArk may be batteries optional.
Sunny Boy is a grid-tie inverter that provides up to 2000W (given enough PV and sun) of batteryless backup, a feature called "Secure Power". For a time, that feature was disabled if your system had "Rapid Shutdown" as required by code in many areas, but I think they've found a way to make it work now.
My system is (older) Sunny Boy with (expensive) Sunny Island battery inverters. It makes a very nice on-grid/off-grid system but probably costs $10k and up.
What do you think of the Alibaba 200AH lifepo4 batteries for $229.00?
You won't be able to run an AC overnight with a $1000 battery bank. When the sunsets/night, what really matters is the amount of energy/stored in your battery bank. A small 5000BTU window AC uses around 500w every hour. Battery technology is not ready for heavy demanding power hungry appliances like AC without breaking the bank. You would need a generator or car alternator to constantly provide 40Ah to 50Ah draw that a small 5000BTU needs. That is too much for two 100Ah batteries to handle for 8-12 hours of night time.Hi guys, new in the community, getting older, worry and wise (just kidding). Beginning my preppers life and i am considering for the moment (limited by resources like many of you i supposed) a solar emergency setup system for when hurricanes (living in South Florida) or other emergency arise. I was considering something capable of keep the fridge, the freezer and a couple of light running for 4-5 days when needed, not spending more than $1000. Have been looking at 320 watts panels from Amazon. Should be enough running two of those with two 100 ah batteries for supplying AC for home at night? I do not worry much over day because in South Florida we do have a lot of sun everyday, just don't know if two 320 watts panels should be enough for keeping things runnings and recharging batteries at the same time. Been looking around in the forum but couldn't find something specifically to my needs. Any help is apreciatted. Will consider expanding the system in the future when everything works to my like.
Wow, couldn`t ask for more detailed info even to my brother. Thanks Hedges, you make things clear to understand and right to the point, very valuable info indeed. I haven`t decided which way to go, if finally i decide to go big, i know for sure that seeing that i am only able to use 10PV, the installation will need to be grid tie.Is that price per individual cell, or for a 12V pack of four?
I haven't bought any, but many on the forum buy LiFePO4 cells and assemble batteries. There are a couple of vendors people here recommend, while others are unknown or people report bad experiences.
An assembled battery will have questionable BMS and wiring (except for a couple premium priced brands.) A BMS protects cells against over/under charge, hopefully prevents charging below freezing, and provides some amount of balancing but only among the cells it controls.
A 48V system is good for any but the smallest (e.g. < 2kW) inverter. For a 48V system, best to use a 16s bms so all cells balanced together. If you use 4, 12V batteries with their own BMS they may get out of balance, you might periodically charge separately.
A system can have BMS that doesn't communicate with inverter, but best system will have them talk. That way, charge can slow down and wait for balancing to occur.
It all depends on the capacity, performance, quality, price you want. At first you were looking for $1000 backup for fridge, then $5000 system that offsets utility bill. Hope you plan to stay connected for several years, ideally a decade, to get your money's worth. Grid-tie has quicker payback, but battery backup costs more without giving any more watt-hours.
For battery backup, you need to understand your loads: watt-hour, maximum load, starting surge.
First examine your electric bills, determine average Wh/day in winter and summer.
Read your electric meter just before sun goes down (or stops shining on your planned panel location) and in the morning before it will start producing power.
Identify largest motor to be run.
Some people buy a kill-a-watt meter to measure appliances.
Motors draw about 5x their nameplate rating to start, so a window air conditioner rated 500W needs 2500W for a second to start.
Refrigerators have a smaller motor; most of the current draw is defroster.
Your inverter rating has to be sufficient to start the loads.
Battery capacity has to be sufficient to make it through the night.
My AGM battery which cost $5000 is barely enough to get through one night. A different house with one newer refrigerator might use half as much. A sufficient size DIY LiFePO4 might be $2000 for 48V or $1200 for 24V.
From the figures you've given so far, 20 x 1400 Wh = 28 kWh is your daily consumption.
One night could be 14 kWh, hopefully less.
Your PV system will be 8 x 1400 Wh/day = 11.2 kWh, plan for 5 kWh at night
People here buy LiFePO4 280 Ah cells for about $100 or so, 900 Wh each.
A 24V 8s pack would be 7.2 kWh, cost about $1200 with BMS. That should last one night if you cut consumption when running on PV.
Doing a 48V 16s pack would let the house run one night at full consumption, but you don't plan enough PV to recharge in one day or run the house.
A generator (and suitable generator input to inverter) could work, if inverter tolerates frequency of generator.
Lithium batteries should handle nightly 80% cycles for a decade, but backup application won't make use of that. If you have time of use rates and PV smaller than total household consumption, you may find you are still a net consumer during peak times. "Peak shifting", using batteries to store power when produced and provide power during peak times so you don't draw from the grid, may be a cost-effective application of the batteries. I think DIY LiFePO4 can cost $0.05/kWh (over a decade) and utility rates could charge $0.20/kWh premium for peak hours; depends on local rates. The right inverter can be programmed to shift peaks. That's something Tesla Power Wall and SMA Sunny Boy Storage do. I think some of the low-priced inverters do to but not sure which ones.