Need help in designing DIY Emergency Solar System for small apartment

Re: Need DIY Off-Grid for Small Apartment

Not really--If you are careful and understand the basics--You can do OK. There will be a few mistakes (we all make them)--But if you like a little DIY, it can be done.

Keep your first system "small" -- It is not much different than working on your car.

Here are a couple of links:

BB. wrote: »

Add this link to our Solar Beginner Post:

Emergency Power

Basically a very long thread that starts from the beginning with a few vague requirements through design and assembly for a "portable" solar RE off-grid power box.

And here is another example by Mike90045 called the Solar Monolith:





Update pictures/information here.

-Bill

Note--You may not even need a solar panel (if you don't have full sun for 3-6 hours per day somewhere, solar panels do not do you much good... Charging from AC power (short outages) or from your car or small genset (like the Honda eu1000i), for longer outages.

But the way, I suggested propane stoves--But there are the old "Sterno" gelled gas/alcohol stoves for survival that work well too:

http://www.amazon.com/s/ref=nb_sb_ss_c_0_15?url=search-alias%3Dsporting&field-keywords=emergency%20stove&sprefix=emergency+stove%2Caps%2C420

The big problem with any emergency/portable stove, you have to be very fire safe--Not many of them are really safe to use indoors on a kitchen table (they throw off too much heat towards the table) and/or are not real steady (easy to knock over).

For boats, alcohol as a fuel was much safer--If there was a spill/fire, water will put out an alcohol fire/dilute the fuel--Gasoline and Kerosene/Diesel will float on water.

You can use inexpensive propane stoves and screw-in cylinders (used for cooking on a table)--But I am not a fan of them for emergency use... I have seen the "cheap" propane cylinders bleed to empty if stored for a few years. The heavier 16 oz cylinders (and larger) don't seem to have that problem (links are just examples of what I am talking about--Not suggestions of what/where to purchase).

The D cell (and AA cell) alkaline batteries these days are dated and should last >5 years if purchased fresh... Use the LED Lantern, get an AM/FM emergency radio, and a couple LED Flashlights, etc. and you "standardize" on cells/batteries (everything uses the same one or two types of cells).

If you hike and use a flashlight, etc... You will naturally use your stock up and rotate anyway. And, you will know if something has failed before the next emergency use (you should have 2-3 of something, flashlight, backup radio, etc. anyway--Having one item, that can fail anytime, and no backup is not a good plan).

Anyway, you will have to replace batteries after 5 years--D/C/AA/AAA anyway--And they are a lot cheaper than a pair of Deep Cycle Lead Acid Batteries--And the golf cart batteries will have about the same life.

You can get AA to USB adapters (like the little Goal Zero I had a link too)--They can be filled with AA alkaline cells and used to charge up your cell phone/MP3 players too.

A 12 pack of D cells and/or 48 pack of AA cells is something less than $15 each--They will provide you weeks of lighting/radio/cell phone power if used reasonably (not 24 hours per day).

-Bill

Re: Need DIY Off-Grid for Small Apartment

Lioness29 wrote: »

I looked at the "Emergency Power? thread you mentioned in your last post. With my pared down wish list (A light to read by (LED is fine), recharge smart phone & laptop, run a small fan and, ONLY if possible, run a 500-600watt cheap microwave) are the specs listed below what I'm looking for? I really think I need to buy something locally so that if I have trouble I can go back to the vendor. 1) Where would I go to get something like this? 2) Do you think this system would fit within my $500 price? 3)Could you fill in the gaps in my specs. I just don't understand volts and amps, AGM, flooded, resistance, etc. If I have specs, I can go to a store with my little piece of paper in hand and get them to fill my order.

All the loads you want to run are "small" -- Until you hit the Microwave. Then (like a fridge), you are in a whole larger class of off grid power system and just not really worth it/practical for apartment use.

For an oven, there are options:

• 12 volt Microwave Oven (and 24 volt too)--Don't need a large inverter
• Camping Stove+Oven (use propane cylinders or larger tank) Costco in our area is closing out for summer at ~$130
• Camping Oven (propane)
• Camping Oven -- Set on stove burner

Almost any other can be done with flashlight batteries... And while you can get a small to medium solar panel and recharge AA batteries (Sanyo Eneloop "pre charged" NiMH batteries can hold charge for 1 year), they are expensive and can take a full day or two of sun to recharge. A pack of 48 AA batteries will last you 10+ days if you were to use a set of 4 up every day... Usually they will last much longer than 1 day for 4 AA's of use.

Going through the recharging can be akward. If you don't have good sun or are on the move, you cannot just set the charger+panel on a table in the park/common area and walk away--The charger setup will probably "walk" too. And it will take most of the day to recharge a 4 set of batteries--You might have other things to do with your time.

A package of 48 AA alkaline batteries (good brand like Costco's or Duracell) for $15 or so will last 5+ years. If you want to be really sure--Get a new pack every 2.5 years or so, and simply use the oldest batteries first.

Inverter: 600 Watt Sine Wave Inverter
Battery: Deep cycle; (AGM or standard flooded?) 12 volts; 34 to 85 Amp-hour Concorde AGM totally sealed battery - they have very low internal resistance and cannot leak.
Battery charger: Regulated 12volt, 15 amps?
Cables: Kind? Length? specs?
Misc equipment needed?

Sorry--Math... A 34 AH @ 12 volt battery will hold (very roughly):

• 12 volts * 34 AH = 408 Watt*Hours

A 600 watt inverter used at full power, will drain such a battery in:

• 408 Watt*Hours of storage * 1/600 Watt load = 0.408 hours = 24 minutes to dead

And note that 600 watts through an AC inverter or 500 Watts through a 12 VDC car type microwave oven--It is the same--A watt is a watt, no matter how it is generated or used.

Concorde AGM batteries are very nice... But you will have to recharge it every ~3 months or so (~1 day on a battery charger, or "float" on a charger permanently plugged into a wall outlet).

Also with any Lead Acid rechargeable battery--They do not like to be stored at less than full charge and will die if taken "dead"--They are pretty rugged--But they do have their limits if mistreated (over charging is also mistreatment).

Even though this is a "solar forum"--There are some things that solar+rechargeable batteries simply are not great for... And setting up an apartment system for a few hours to a couple of days of outages maybe once or twice every couple of years--Is difficult to justify.

I won't get a solar panel to begin with so I would just charge the battery with my car?

You can--But the larger the storage battery, the longer you would have to idle your car to recharge the storage battery.

For example, a 4x AA battery charger could just be connected to your car and left... You don't have to run your engine to recharge. An 85 AH Concorde battery taken "near dead" connected to your car--If you did not run the engine, the recharging of the dead battery would drain your car battery by 1/2 if the engine is not running--possibly damaging your car battery or leaving you unable to start your car. It would take several hours of "idling" to 8+ hours of idling to get the Concorde mostly recharged (depending on your car and exact charging electronics setup). Still--Not very practical and can drain your tank by 1/4 or more... Not always a good idea to "waste" vehicle fuel in a true regional emergency when gas stations are shut down too.

What is this for and do I need it?
"Converter" (DC power supplies). These allow you to run DC equipment designed to run from a battery from AC.

A Battery, small AC inverter, smallish AC Battery charger, and some wiring, connectors, a fuse or circuit breaker, and you are about ready to go--But I am still trying to get you to forget any "large loads"... A laptop computer (~30 watts) would be the largest appliance I would suggest for your emergency power system...

Unless you have a good place to store (for example) a wagon/cart/hand truck with ~100 lbs of battery+inverter+battery charger (closet or outdoor lockup where you can roll-in the power cart). if you are not in a ground floor apartment--You may not have an elevator--And dragging 50-100lbs+ up and down stairs (storage, recharging, etc.) is not really an option unless you are really into this off grid/emergency power stuff.

For example, a 100 AH 12 volt Concorde battery could power a 30 watt laptop + 10 watts of LED lighting and small radio:

• 100 AH * 12 volts = 1,200 Watt*Hours
• 1,200 Watt*Hours * 0.80 = 960 Watt*Hours usable DC power (don't ever take battery "dead")
• 960 Watt*Hours * 0.85 typical inverter efficiency = 816 WH of usable AC power
• 816 Watt*Hours 1/(30+10 watt load) = 20.4 hours

So--If you want to use your laptop+lights+cell phone with a 100 AH battery and an AC inverter, you are looking at ~2 days of usage at 10 hours per day--Or ~3 days at ~6 hours of usage per day, etc...

Sorry, not trying at avoid answering your questions about hardware--But until you know your loads, the hardware question is not really answerable (or I can give you lists of answers which will just confuse the issues even more).

-Bill

Re: Need DIY Off-Grid for Small Apartment

Lioness29 wrote: »

Sounds like an AGM battery is not a good idea since I would need to charge it every 3 months. Would my best choice be a standard flooded battery? Is there a disadvantage to this type battery? I want one that is safe to have in my apartment and won't leak.

Actually, AGMs are very nice batteries... Almost the "perfect" Lead Acid Battery.

AGM, GEL, Flooded Cell Lead Acid are all "Lead Acid" chemistry batteries that operate pretty much the same way. The difference is the "electrolyte".

A Flooded Cell L.A. battery is just a regular L.A. battery with liquid electrolyte (distilled water and some sulfuric acid). Just like your car battery (plates are heavier/thicker in the typical deep cycle battery. Car plates are thinner and more of them--Get "higher cranking current" from a smaller battery).

AGM Batteries are "Absorbed Glass Mat"--Basically, fiber glass mats between plates--Sort of like a sponge. That and some other "Minor Changes" make AGM batteries manage higher currents and very deep freezing temperatures where they will not freeze and split the case (flooded cell batteries in very cold cold (much less than 0F) can freeze and crack the cases). An AGM battery cannot "spill" electrolyte. The battery caps are also "sealed" and have a catalyst that helps recombine hydrogen and oxygen back into water ("sealed battery"). Over charging can cause the battery to "vent" acid mist/gases (also when AGMs get old and start failing, they can vent).

GEL batteries have the electrolyte "Gelled" to hold it in between plates (like AGM). Many of the same advantages as AGM -- BUT GEL batteries do not tolerate "high charging current well" (in general).

AGM (and GEL) have lower self discharge and only need to be recharged every 3 months. Flooded cell batteries need to be recharged every one month or so...

But self discharge is usually an issue for almost any type of rechargeable batteries.

So here is my newly revised list:
Lap top for ~6 hours per day
Cell Phone for ~1 hour per day
10 watts of LED lighting for ~6 hours per day
Tiny fan: 120V AC 60Hz 0.3 amp for ~8 hours per day (I have one already)

Getting closer.... Still you need to use a Kill-a-Watt meter to measure your proposed AC loads. Leave it plugged in for 1-3 days and get your "average" daily usage.

I can "guess"--But I could be way off too... Like me guessing your car gets 20 MPG--Maybe it does, maybe it does not... I have no idea.

Would this be the system specs to power the above list?:
Inverter: 600 Watt Sine Wave Inverter (Is this "small"?)
Battery: Deep cycle; (Standard flooded) 12 volts; 100 Amp-hour Concorde totally sealed battery
Battery charger: Regulated 12volt, 15 amps? (Is this "smallish"?)
Some wiring, connectors, a fuse or circuit breaker

You could use a 100 Watt inverter... A MorningStar 12 VDC TSW AC inverter would probably be ideal. It has a "remote on/off switch" and "search mode" (it will go to "lower power standby" if there are no AC loads). Read about it first... You could always go with smaller/other product if this is not right for you--But it is one of the "high function" AC inverters that is still very small and efficient (and not too expensive).

The 100 AH Concorde AGM battery would be best for your needs (assuming the price and ~66 lbs of lead does not scare you off)... Flooded Cell is not good in an apartment. GEL is similar to AGM--But not generally not great for solar power (takes very low charge rate).

Concorde PVX-1040T

For a good quality AC battery charger, look at this Iota + IQ4 module (I think Iota needs to supply a non-stock IQ4 for use with AGMs--You would need to call them and find out):

Iota DLS-15: 12 Volt 15 Amp Battery Charger
Iota IQ4: plugin 4-stage controller for Iota chargers

This battery charger is only 8 amps maximum--But it is fine for use with your 100 AH 12 volt AGM battery--It will just take longer to recharge after a power outage. The only issue I found using it--If you disconnect AC power, you have to set it for your battery again (it defaults to low current GEL battery charging--not the end of the world):

BatteryMINDer Battery Charger / Maintainer with Desulphator - 12 Volt 2/4/8 Amp, Model# 12248

If you want to charge the Concorde from your car--We will have to talk more.

Have I left anything out? Also, if I should decide to add a solar panel to the above system, would it be feasible?
Thanks much!

A circuit breaker/fuse or two... Wiring. Still would suggest some sort of cart/hand truck to hold it all--Unless you set it up in a closet and run a cord to the AC charger...

The Morningstar inverter will need an outlet or sort cord+outlet wired to it--It does not have an AC outlet as part of its design.

Yes, you can add solar panels later... ~170 watts would be a good "nominal" panel for your 100 AH battery--Again, lots of discussions about panels and solar charge controller options.

-Bill

Re: Need help in designing DIY Emergency Solar System for small apartment

Did you get to measure the idle current on it?

I do like the Morningstar as a smaller inverter (1,000 watts is a lot of power and requires a lot of battery bank to run it). Also the Morningstar has "search mode"--But the MorningStar and the Sunforce appear to have remote on/off inputs (Sunforce comes with a key fob+receiver for remote on/off).

I like that the MorningStar does not have a fan--pulling dust through electronics is not great).

-Bill

Re: Need help in designing DIY Emergency Solar System for small apartment

24 watts is not great for a smaller system--But probably in the ball park for that size/class of TSW inverter.

-Bill

Re: Need help in designing DIY Emergency Solar System for small apartment

Conversion/standby losses are the bane of any system... And they can add up.

24 watts * 24 hours * 365 * 1/1,000 W per kW * $0.20 per kWH = $42 worth of utility power cost for me

My average monthly electric bill (before I got solar GT) was in the range of $30-$60 per month--So that would have been significant for me (~210 kWH per year or 1/2 of the yearly cost of an Energy Star rated 20+ cuft refrigerator).

-Bill