A simple, inexpensive, yet powerful solar storage system

[PoorOldCountryBoy]

It's a bit more expensive, but also take a look at Powerwall. The units are about the size of a thick card table, cost approximately $6K-$7K and can provide several days of power.

-Wino

We looked at a powerwall, indeed the best for what we needed, but one minor problem: concern about Tesla backing up its products. If anyone has actual experience of Tesla responding quickly to a bricked (unfunctioning) powerwall, please share!

 

[PoorOldCountryBoy]

I can log into my account at SRP (Salt River Project) to see the kWh used in each hour period. The early morning hours when we are asleep is when the energy usage is the lowest at 300 W. I guess the lights in front of the house, and the parasitic drains of all the electronics such as TV, HiFi, DVD players, desktop PCs and laptops, Internet modem and WiFi router, microwave, etc... can easily add up to 300 W. But that's 7.2 kWh/day!

What can one do? You cannot go around unplugging them all, and only plug them back in when you use them. We want everything at the ready to serve us when we push the On button on the remote control, and that's the price to pay. The "on/off" button on appliances and devices now is just a "on/standby" switch. A few watts here and there, and we talk 300 watts for the whole house.

If in the course of 24 hours, a family takes enough showers and uses enough hot water to empty a 50-gal water heater, it takes another 7 kWh to reheat that water from 60F to 120F.

It's amazing how you become more conscious of your usage when you have to worry about how to generate, obtain, or conserve a resource yourself. When we travel in the motorhome, it's amazing how little water we use for dish washing and shower.

I'm surprised you have not used solar hot water heating -- we've had one on our house installed in the mid 1980s, still going strong!

Note - For our implementation it is our source of hot water for about 8 months, then in the winter months we use it to boost temps in the oil furnace, since it is heating the house anyway. If you want 12 months a year you'll need evacuated tubes, not the older flat panel heaters.

 

[NW-Bound]

I'm surprised you have not used solar hot water heating -- we've had one on our house installed in the mid 1980s, still going strong!

Note - For our implementation it is our source of hot water for about 8 months, then in the winter months we use it to boost temps in the oil furnace, since it is heating the house anyway. If you want 12 months a year you'll need evacuated tubes, not the older flat panel heaters.

When I bought my 1st home in 1980, solar water heater was the vogue. I installed one myself, using a kit that was offered by many retail stores then.

In 1986, when I moved to the larger home I still live in now, the previous owner already had two large solar panels installed, feeding two 52-gal heater tanks.

I maintained and used the above solar until 2007, when a rare freeze took out both panels and it was also my fault for not checking that the anti-freeze pump and sensor was working properly.

I opened up and rebuilt one of the two panels, and that took a lot of work to braze, not solder, the internal copper tubing grid. It was a very nicely built panel too.

The repaired panel sat there for 10 years, awaiting the time I feel like installing it again. It was finally hauled up to the roof and mounted. I still need to solder the plumbing and the circulation pump.

Then, I got this idea about the electric solar system, and the water panel is still sitting forlorn on the roof.

And I have been using surplus solar power to run the electric water heater as a load dump when the batteries are full and there's no place for the juice to go.

Next year when I install a 2nd minisplit, I doubt that I will have any surplus power for the heater. But then, I may get gun ho and install more PV panels.


PS. Here in the Southwest, a flat panel works in the winter too, and fancier evacuated solar collectors are not needed. The output is reduced, but is still usable.

 

[ncbill]

Here's the last piece of the system, the combo solar charger/AC charger/inverter. It's the MPP Solar PIP-2424LV-MSD. It uses the battery voltage of 24V, has an inverter output of 110V/120V, accepts up to 2kW of solar power to charge the battery at 80A, and can use the line voltage from the grid or a generator to charge the battery at 60A.

I spent a lot of time looking at inverters and chargers, and found that MPP Solar, a Taiwanese company, has a line of very attractive combo inverters/chargers. I searched the Web for info on this company, and found a forum of Australian DIY'ers who had good experience with this brand. Their favorite model is the PIP-4048MS and PIP-5048MS, which run with a 48V battery and output 230VAC.

The forum is called forums.aeva.asn.au, and has a couple of members with technical expertise to hack into the above models' firmware to change some parameters. They know a lot about the internals of the inverters. Their consensus is that the machines are a good buy for the money, and that convinced me to get one myself to use. I ended up buying 2 more, and now have 3.

I really wanted to get a 48V model, as the higher voltage reduced the amperage, and would allow smaller gauge wires for interconnects. However, MPP Solar for some reason does not make 48V models that output 110/120. So, I had to use the 24V inverters.

I do not have the exact above model, but its close relatives. One of the 110/120 inverters has been running for almost a year. It powers my fridge and some of the kitchen outlets. The 230V, also of 2.4kW output, runs a 1.5-ton minisplit AC/heatpump since spring. I am waiting to tear down the system mounted in a garden shed to rewire everything neater and to mount another 110/120 inverter. This one will power additional AC circuits for the home.

This brand of inverters and its various clones are in use worldwide. Some say the other brands are copycats, and some say they are under license. I don't know what the truth is.

You can search the Web, and find many people using this brand. Look on Youtube too.

An inexpensive transformer converter solves that issue.

With an input of 120/240VAC it provides separate 120VAC & 240VAC outputs.

e.g.: https://www.amazon.com/SEYAS-Transformer-Converter-Continous-Protection/dp/B07QXYR7VY/

So for the home I'd get the 48VDC MPP Solar model & connect eight 6V GC2 batteries in series.

Did you move the circuits powered by the battery bank to a sub-panel?

 

[NW-Bound]

I considered that, and not used the idea.

I thought about using a 48V system and an MPP Solar with 230V output. Quite a few US DIY'ers have done this, and they use a transformer to get 115V.

I shopped for, and bought an industrial 115/230 Acme transformer, the type that a utility company or a factory would use. Nice and heavy unit, and outdoor mountable too. Just beautiful.

But when I tested it, this transformer drew 60W when idling. That's 1.44 kWh/day being wasted. Then, I realized that I would need more than one inverter. More wasted power! This drove my decision to use a 24V system, and I now have two 110/120 inverters and one 230V.

The beautiful and heavy transformer is sitting there unused. Another addition to my pile of parts.

PS. My plan is to have the inverters powered on/off individually, and automatically. Each inverter takes 25-30W when idling, and just taking the load off them with an autotransfer switch will not save that power. I want to power down the idling inverters too.

A homebrew control system using a microcontroller will do the above function, in addition to the BMS (battery management system) function.

 

[NW-Bound]

Did you move the circuits powered by the battery bank to a sub-panel?

Street asked me a similar question earlier, and I answered on post #46.

Yes, the connection from the inverter outputs to the house circuits takes place inside a subpanel, which also houses the auto-transfer switches.

 

[NW-Bound]

For someone who just wants to start out with something simple to understand how things work, it can be a lot simpler than what I talked about with my own installation. Don't worry about that stuff yet. Don't let that confuse you.

To use a portable generator to power the fridge and some lights, people just run an extension cord from the generator sitting in the back patio into the house. You can start out with this solar system doing the same thing, and have everything in your back patio (out of the rain, except for the solar panels), and use an extension cord to bring the juice inside to enjoy.

In summary, here's what you do to start and to learn about this.

1) Get the MPP Solar unit. Look on eBay.

2) Look locally for suitable used solar panels, using the info I provided earlier. You can start with just a single panel, or 2 wired in series. Put them out in your backyard, facing south and tilting up with blocks. Obviously, they should be facing the sun directly at noon for maximum power, and the sun angle varies with the season. You will need to use cables with MC4 connectors. Look on eBay for ready-made cables, or you can build your own if you buy the bare connectors. Wire the string up to the MPP Solar.

3) Get 2 12V marine batteries at Costco or SamClub, or 4 6V golf-cart batteries at SamClub. Wire them up in series for 24V. Then wire the string to the MPP Solar.

4) Wire an extension cord to the MPP Solar to bring the juice inside.


That's it. Oh, don't forget to turn the switch on the unit to "On". And read the manual too.

For emergency use, that's all you do. If you want a more permanent installation, you can ponder about that later, or you may want to enlist help.

You can start playing with this for less than $1000 with the MPP Solar, one solar panel, and 2 batteries. Add more panels and batteries later.

Once you see how it works, like it, and get hooked, you can expand it later and wire things in a more permanent fashion in order to save on electricity costs. And at that time, you can think about transfer switches and sub-panels and all the niceties.

I will describe how the MPP Solar can be hooked up to a generator next.

 

[NW-Bound]

I need to finish describing what happens when you wire the MPP Solar to an AC source, such as the grid or a generator.

The unit can use the external power source, in conjunction with the solar power, to charge your battery. It also has an internal transfer switch to turn off the internal inverter, and pass through the power to the load. In this mode, it is like the typical computer UPS (uninterruptible power supply), which keeps its battery charged up in order to be ready to take over when the grid power fails.

But, but, but this cannot work to use the solar power to help reduce the power consumption off the grid, when there is no outage. When the battery is full, everything goes to standby, and the charger go to sleep. All that solar power is wasted.

Yes, the above is true. But you can put the MPP Solar into a different mode. In this mode, it will ignore the external power source, and continues to use the solar power to charge the battery and simultaneously use the inverter to supply the load. If the solar panels provide more power than you use, this excess power is accumulated in the battery for use at night.

When the battery runs out, it will stop the inverter to save the battery from being ruined, and switch the load back to the grid. This is how you can use this off-grid solar system to help with your electric bill. When the unit transfers back to the grid because of low battery, you can tell it to charge the battery with the grid power or not. When not in an outage, you will want to tell it not to charge with grid power, and to charge only with solar power.

In a power outage situation, you will have the system plugged into a generator, not the grid. When the power runs out, you will have to go start up the generator. If the generator has an electric starter, the MPP Solar has an auxiliary output that can be used to command the generator to start when the battery is low. Many inverters, and even solar charge controllers, have this generator-starting feature.

The above features have thresholds and criteria that are programmable by the user via the front panel, or by attaching a PC and running a program. There are a few things you will need to play with. For example, the unit can use up to 1500W off the generator to charge the battery. With a 2000W generator, that would leave only 500W for the load, and that's not enough. You can program the unit to use less power for charging in this case.

The MPP Solar units have quite a bit of functionality and flexibility. That comes from combining 3 functions of Inverter/AC charging/Solar charging into one unit, so that their operation can be coordinated. And again, the price is hard to beat.

Last but not least, it is made by a Taiwanese company. I am prejudiced, and prefer that to mainland China products when everything else is equal.

 

[meierlde]

A couple points to consider with the above: first when designing the battery system you should plan for getting only 40% amphour capacity out of each battery. Any more than that and they won't last very long. Another point is that not all lithium battery chemistry is dangerous and can cause fires if overcharged. Lithium Iron Phosphate (LiFePO4) chemistry is very safe, actually safer than lead acid batteries and is the preferred type in RV's.
Another point is to use a pure sine wave inverter to eliminate problems with electronics.

I agree about the sine wave inverter, and if one is getting a generator get an inverter generator which puts out sine wave power. (also the generator makes less noise as it does not run at a constant 3600 rpm like a traditional generator, when lightly loaded) For LiFePO4 batteries they can handle a deep discharge with the proper charge controller see BattleBorn Batteries for details https://battlebornbatteries.com/?gc...h_Tuu31OXV7ZQD7_oJMaa4aL_42bBI4YaAhLoEALw_wcB

((Roughly 949 for 1.2 kwh)

 

[NW-Bound]

LFP batteries are great, if one does not mind the cost.

I have 3 of the 100Ah batteries in my motorhome (made by Lithionics), and 22kWh worth in my DIY home system built with 960 cells of the 32650 physical format.

As the total price for just the battery goes up to the $10k, one should look into the professionally built and installed Powerwall 2, which stores 13.5 kWh per unit.

However, do not think that the total cost will be as low as the price of just the bare unit.

The list price for a new Tesla Powerwall 2.0 battery, which offers twice the storage capacity of the original Powerwall, is $6,700. Supporting hardware adds another $1,100 to the equipment costs, bringing the total to $7,800. Installation can add anywhere from $2,000 to $8,000 to the final bill.

PS. Tesla Powerwalls are not of the LFP type, but nickel-manganese-cobalt chemistry.

 

[neihn]

I have a Goal Zero Yeti 1000 with the optional mppt unit and a 100 watt solar panel. I used it for my van camper, it is good enough for running couples 12v fans all night, LED lights and watch movies on laptop. Perhaps, some light cooking with inductance stove (boiling water, fired egg etcc...), but I have propane cook stove for cooking.

It is expensive but it's a simplest way to get solar for camping.

I love to do something similar to NW-bound in the future.

 

[morriss003]

I've used Optima gel cell batteries (yellow top) for a couple decades. Haven't replaced one yet.

 

[NW-Bound]

I have not used Optima batteries but know that they are of the AGM (absorptive glass mat) type, and the electrodes are rolled up in a cylindrical form to increase surface area. AGM batteries are the best among the lead-acid type, but having one lasting that long is amazing.


Regarding Lithium Iron Phosphate batteries (or LFP for Lithium FerroPhosphate), the various batteries on the US market right now are all made using Chinese cells. I opened up my Lithionics batteries and found CALB cells inside.

LFP batteries on the market now command a price of around $1K for a 12V-100Ah battery. Buying cells from CALB (China Aviation Lithium Battery) or GBS and assembling your own battery can get the price down to $500 for the same capacity.

I expect to see more importers bringing more Chinese-made batteries onto the US market in the next year or two. Their price is currently about $350 or less for the above capacity, but the shipping cost for retail purchases is high. An importer needs to buy and ship them by the semi-trailer load to bring down the shipping cost.

 

[NW-Bound]

I have a Goal Zero Yeti 1000 with the optional mppt unit and a 100 watt solar panel. I used it for my van camper, it is good enough for running couples 12v fans all night, LED lights and watch movies on laptop. Perhaps, some light cooking with inductance stove (boiling water, fired egg etcc...), but I have propane cook stove for cooking.

It is expensive but it's a simplest way to get solar for camping.

I love to do something similar to NW-bound in the future.

This might be something of interest to Sunset, who asked for a portable solution, yet powerful enough to run his sump pump at a remote cabin site. The above device has an output of 1500W, which may be enough. Storage capacity is limited at 1 kWh, but Sunset said his pump runs only for a minute at a time.

 

[NW-Bound]

Working with batteries and solar panels, you will want to be able to measure DC currents without having to break into the lines. Thank goodness, there are now inexpensive DC clamp ammeters that will let you do this.

Old-style current clamp meters use an inductive coil, and they can measure only AC currents. New current clamp meters use a Hall-effect sensor, and they can measure DC currents also. This is really a godsend.

A inexpensive unit that has good reviews is the UNI-T UT203. The UNI-T UT210E has more current measuring capabilities. I have a Craftsman, but have been thinking I should get a Uni-T, just to have.

 

[ERD50]

....
A inexpensive unit that has good reviews is the UNI-T UT203. The UNI-T UT210E has more current measuring capabilities. I have a Craftsman, but have been thinking I should get a Uni-T, just to have.

Thanks, I had sort of been looking for a clamp current meter, but only found AC ones. I'd like to measure currents on my hobby projects w/o breaking the circuit open.

Just bought a UNI-T UT210E on ebay, new, US shipper. $36 shipped, will be here next week.

The E has a 2 Amp range, so 1 mA resolution - but reality is +/- a few digits, 2%, and some 'noise' to cancel out and deal with from the Earth's magnetic filed, and I suppose any other local magnetic field.

In the future, I'll plan on adding a loop of 10 windings on any low-current project that I plan to monitor current on. That should raise the field by 10x, getting it further out of the noise (someone in a review mentioned using 2 loops to double the field. 10 gives an easy move-the-decimal reading).

edit/add: Holy Cow! Some dedicated DIY types re-flash this thing and mod it to increase bandwidth, bring the current measurement out to put it on a scope, etc (I just skimmed, probably a lot more). One thing they change is to have it default to DC instead of AC - that makes sense, most people probably buy this for the DC capability (like I did). And mod the back-light timing? I probably won;t use it enough to justify any of that, but it's kind of fascinating. Wish I could hack my home thermostat - I hate the UI on it, and there is good info in there, but it's buried deep in the menus!

https://www.eevbalog.com/forum/testgear/a-look-at-the-uni-t-ut210e/ 28 pages!!!

https://github.com/bdlow/UT210E

-ERD50

 

[NW-Bound]

DC clamp ammeters are affected by the earth magnetic field, hence they all have a "Zero" button to compensate for that constant field. You will always want to reset the meter to zero before clamping it around the wire whose current you want to measure. And in moving the meter towards the wire, try to keep the orientation of the meter the same. When I rotate and spin the meter to point in different directions to see the effect of the earth magnetic field, I can get a reading as high as 0.12A.

My Craftsman meter has a max count of 4000. I have two ranges: 40A and 400A. At the lower 40A range, the resolution is 0.01A, which is plenty.

I am curious to see if the reading of the 2A range on the UNI-T will be steady, because with a count of 2000 the resolution is 1mA, and the stray earth field is already 120mA on my meter.

Anyway, DC current clamp meters are great. I use it to check the balance of current between my two halves of the DIY lithium batteries. I decided to build 2 cabinets, each holding 11 kWh and at 24V. This way, I can use them as two 24V batteries in parallel, or wire them in series for 48V. The two cabinets are also of a more manageable size (each is about the size of the Tesla Powerwall), and weigh more than 200 lbs each when loaded.

I ended up using a 24V system, and wired the cabinets in parallel. Due to the slight difference in the internal wiring, one cabinet has a higher resistance than the other. You are talking about milliohms. That causes a slight imbalance in the currents. The cabinet with the lower internal resistance has been working harder than the other. When I tear everything down to rewire, this is also part of the rebuilding job.

 

[NW-Bound]

Working with batteries, you will also need a good meter. Here's what I found about the use of a DVM with lithium batteries.

Most of the DVMs are of the 2000-count type. This means that to measure DC voltages, they have the ranges of 2V, 20V, and 200V. When measuring the voltage of a lithium cell, which is nominally 3.8V for the common NMC type or 3.2V for the LFP cell, the meter will be in the 20V range. The voltage will read 3.31V for example. Isn't that good enough?

The issue I have seen particularly with LFP cells is that their voltage is extremely flat against the state of charge. Two cells both reading 3.31V may be at 3.310V for one, and 3.3199V for the second. An imbalance of 9 millivolts may mean a difference in SOC (state of charge) of 10%. If you put two such cells in parallel, large-format cells will develop tens of amps flowing between them, due to their very low internal resistance. While in use, you want cells in series to have as equal voltages as possible.

For this reason, I like to use my 4000-count DVM when checking cell voltages. Such DVM will have a resolution of 1 mV when measuring cell voltages up to 3.999V. That is plenty for LFP cells, because they should not be charged over 3.6V.

For other lithium types which can go up to 4.2V, I can use another DVM with 6000 counts, which will go up to 5.999V and still provides 1 mV resolution.

The above talk is about cell balancing, not absolute voltage measurement. Absolute accuracy to 1 mV when measuring cell voltages is not possible without expensive equipment. And it is not usually required. Still, you can check your meter against a reference voltage chip, such as the AD584 from Analog Devices.

The AD584J will provide a reference voltage of 10V+-30mV, 7.5V+-20mV, 5.0V+-15mV, and 2.5V+-7.5mV. That's 0.3%, and better than your typical DVM.

The above chip costs $10. Or you can get the AD584K, which is 2x more accurate, for 2x the price.


PS. A Fluke 87V will have accuracy to 0.05%. Very impressive. The cost is however $430. I don't own one.

PPS. Out of curiosity, I looked and found a voltage reference chip which has the specs of +-0.01% over the temperature range of -55C to 125C. The price is $160.

 

[daylatedollarshort]

I can log into my account at SRP (Salt River Project) to see the kWh used in each hour period. The early morning hours when we are asleep is when the energy usage is the lowest at 300 W. I guess the lights in front of the house, and the parasitic drains of all the electronics such as TV, HiFi, DVD players, desktop PCs and laptops, Internet modem and WiFi router, microwave, etc... can easily add up to 300 W. But that's 7.2 kWh/day!

What can one do? You cannot go around unplugging them all, and only plug them back in when you use them. We want everything at the ready to serve us when we push the On button on the remote control, and that's the price to pay. The "on/off" button on appliances and devices now is just a "on/standby" switch. A few watts here and there, and we talk 300 watts for the whole house.

If in the course of 24 hours, a family takes enough showers and uses enough hot water to empty a 50-gal water heater, it takes another 7 kWh to reheat that water from 60F to 120F.

It's amazing how you become more conscious of your usage when you have to worry about how to generate, obtain, or conserve a resource yourself. When we travel in the motorhome, it's amazing how little water we use for dish washing and shower.

Our lowest usage recently was middle of the day, no lights or heating / cooling, .23 kwhs. In a 24 hour period that is 5.52 baseline and then we use 5 to 10 more kwhs each day on top of that baseline. That is with the chest freezer still unplugged and unused after the last power outage.

For the next outage I have some additional small scale solar products from Amazon stocked up, like a 6 day lantern that runs on D batteries and a supply of rechargeable D batteries to use with a solar charger, a solar rechargeable power bank, another solar light, and music speakers that run off the power banks. And I bought a low tech solar shower bag for hot water, in case the gas gets shut off next time.

 

[NW-Bound]

Our lowest usage recently was middle of the day, no lights or heating / cooling, .23 kwhs. In a 24 hour period that is 5.52 baseline and then we use 5 to 10 more kwhs each day on top of that baseline. That is with the chest freezer still unplugged and unused after the last power outage.

For the next outage I have some additional small scale solar products from Amazon stocked up, like a 6 day lantern that runs on D batteries and a supply of rechargeable D batteries to use with a solar charger, a solar rechargeable power bank, another solar light, and music speakers that run off the power banks. And I bought a low tech solar shower bag for hot water, in case the gas gets shut off next time.

230 W of baseload is not bad, compared to mine of 300 W. The 300W number is taken when the big 30 cu.ft. fridge is powered off the solar storage battery, and the auxiliary 25 cu.ft. is on the grid.

As mentioned previously, the big fridge draws 4.8 kWh/day, while the smaller one draws 1.6 kWh/day. Both are around 15-year-old.

Is frequent opening the fridge and also using the icemaker causing that much of a power draw? One way to check is to log the power drawn with the Kill-A-Watt when we are on a trip. I will have to remember to do this.

 

[ncbill]

Another battery option is nickel-iron.

On another forum I read of a full-time RVer who made space in the "basement" for twelve 2-volt nickel-iron cells, ordered new from China. They came dry with a bag of potash to mix with distilled water to make the electrolyte.

He camps where temperatures drop well below freezing & so wanted to avoid lead-acid batteries.

 

[NW-Bound]

Nickel-iron batteries supposedly have a very long life, and that is intriguing. But when I check further, their performance is quite crummy.

Nominal cell voltage: 1.2 V
Charge/discharge efficiency: <65%
Self-discharge rate: 20% – 30%/month
Specific energy: 19-25 Wh/kg

That's nowhere as good as even lead-acid batteries.

Yes, lead-acid batteries can freeze and get ruined. When fully charged, the electrolyte turns more acidic, and they are hardy to -90F. But not being able to use it while cold may defeat the purpose of having it.

Lithium batteries can be used when cold to deliver power, but cannot be charged below freezing without damaging them. What's even scarier is that the damage is latent, and may cause the battery to explode much later. At least, that's what I have read.

 

[daylatedollarshort]

230 W of baseload is not bad, compared to mine of 300 W. The 300W number is taken when the big 30 cu.ft. fridge is powered off the solar storage battery, and the auxiliary 25 cu.ft. is on the grid.

As mentioned previously, the big fridge draws 4.8 kWh/day, while the smaller one draws 1.6 kWh/day. Both are around 15-year-old.

Is frequent opening the fridge and also using the icemaker causing that much of a power draw? One way to check is to log the power drawn with the Kill-A-Watt when we are on a trip. I will have to remember to do this.

I have a large side by side fridge and freezer, probably 10+ years old, but I turned off the cold water / ice maker since we weren't using them anyway. I keep reuseable plastic, BPA free ice cubes in the freezer instead.

 

[NW-Bound]

It sounds like your electricity usage is low enough that a single Tesla Powerwall will be enough for 24 hours. And of course in the time of crisis, people will be more frugal with electricity, and it may even last 2 days.

And then, adding a solar array may mean that you can be self-sustaining, except for cloudy days. You still cannot have heating or cooling, except for a small window AC or a mini-split. But not having to worry about spoiled food and having some lights will make the outage much more tolerable.

 

[daylatedollarshort]

It sounds like your electricity usage is low enough that a single Tesla Powerwall will be enough for 24 hours. And of course in the time of crisis, people will be more frugal with electricity, and it may even last 2 days.

And then, adding a solar array may mean that you can be self-sustaining, except for cloudy days. You still cannot have heating or cooling, except for a small window AC or a mini-split. But not having to worry about spoiled food and having some lights will make the outage much more tolerable.

I'm just not going to restock the freezer until rainy season starts, produce keeps in the fridge for 2 days or so, and the eggs and cheese can go in a chest cooler. I think I'm set for the next potential outage foodwise. It got a bit chilly at night but the days were in the 70s, so I'm not really sure we need much power for an outage other than the power banks and other gadgets we have. We had Internet through our cell phones. I bought the solar shower to fill hot water bottles for getting warmer at night if the gas gets shut off, but last time that stayed on. We have a propane stove for cooking and coffee.

I'm more interested on how to have off grid power for the long term. Our electricity use is low enough the grid tie in solar panels aren't cost effective for us. If we could really pull off your 20kwhs for $2K we'd be almost energy self sufficient. We have a gas furnace and hot water heater. The gas water heating bill is only $10 a month, so there's not a lot in changing that. The gas furnace is maybe something else to look at.