Newbie questions and.... help!!!

fordraceboy · January 2014

Hello. I'm looking to get my feet wet in renewable energy, and think a solar/wind combination would be best given my location here in Oregon.

I want to get my shop off-grid, and then eventually upgrade and put part of my home onto either that system, or a new system.

I understand it's better to just do it once, but until I'm more comfortable with all this stuff, I'm skeptic. LOL

Please bear with my thought process below, and then have at it with corrections.

My power consumption for the building is fairly low, I have a freezer and a fridge/freezer, as well as flourescent lights within the structure, and a few external lights. the freezer pulls 5amps and the combo unit pulls 11.2amps. 6- 4 ft dual T8 bulb shop lights and and 6-90 watt incandescent floodlights. The shop lights are used about 2 hrs a week and the floods are nightime motion sensor only, so maybe 1-2 hrs a month.

Here's where I get confused with all these battery numbers- I know that I need about 16A @ 120v for 8 hours a day for appliances, then roughly 4 amps @ 120v for the lights.

Monthly total is approx. 3600 AH @ 120v, or 440,000 watts.

This tells me I need 120 AH a day, so I would need 250 AH of storage to keep from dragging the batteries below 50% each day. Now, keeping the thought process of having a battery bank with 2-3 days storage, I'll shoot for 700ish AH. I've read that 24v is preferred to 12v for simple maintenance, but I honestly haven't tried to figure out a 24v set-up.

I am debating between the Trojan L16RE-B or the Trojan T105RE. The L16's mean fewer batteries, less connections and less parasitic loss. Using L16's would require a minimum of 4 batteries... right?

I'd like to be able and expand this system to about double the abovementioned capability, given that I can keep up on the charge in the battery bank. I figure if I can keep the smaller one charged, it's a matter of adding input to compensate for the drain- I'd just like to know how much input that's going to take given my location.

Opinions on the batteries? Will I be better off to go 24v initially, or just upgrade later if feasible? How many soalr panels am I looking at?

I like this windmill, does anyuone have any experience with them? Better options for low wind areas? (I'm not in a high wind area, although my house is on a ridge so I can get some pretty harsh gusts) http://mikeswindmillshop.com/LowWindGenerator.html

Combination charge controllers? battery bank monitors?

I have a growing interest in this, but unfortunately, can't seem to find easy to decipher info, as it's all greek to me.

Thanks in advance.

Cariboocoot · January 2014

Re: Newbie questions and.... help!!!

Welcome to the forum.

Two things right away: get a Kill-A-Watt meter and actually measure the Watt hour consumption of the things you want to run, and take a look at your electric bill to see how much you are being charged per kW hour.

The first suggestion is due to the fact items rarely use their rated Amps * Volts. Particularly that freezer you want to power. It will have a huge start-up surge (which you won't be able to measure), a poor power factor, and a not predictable run time. Always look at power consumption in terms of Watt hours, not Amp hours; Amp hours are for judging battery size @ system Voltage.

The second suggestion is due to the fact that if you have grid, going off it is just a way to spend lots of money. There will never be a return on the investment because the per kW hour charges throughout North America and most of the world are no place near as high as the cost of producing power off-grid. No, it is not free. Around here it would be more than twenty times as expensive.

Your estimated 440 kW hours per month is about 15 kW hours per day, and whereas that's not unusual for a small household it is a very large amount of energy to be harvested from solar. Frankly you'd be looking at 7 to 8 kW of array at around $1 per Watt just for the panels.

Small wind power is notoriously inefficient and unreliable. It costs a lot for a good turbine and tower to put it on, and then you may find you don't really have enough wind to produce any viable amount of power. Measure the wind first. You can't squeeze blood from a stone and you can't harvest energy that isn't there. No matter what the snake oil salesmen say.

Growing a system over time is difficult, especially if it hasn't been planned for properly to begin with. For example if you pick a 24 Volt system now and need 48 Volt later you end up changing out a lot of equipment, and that means large $ expense.

Think this through carefully and work it out on paper before you spend a dime.

techntrek · January 2014

Re: Newbie questions and.... help!!!

One more thing about wind - it requires maintenance. Lots of it. Parts need to be lubricated and monitored, eventually replaced. One of the big advantages of PV is it doesn't have any moving parts. Worst case, you get a storm system that exceeds the ratings of the turbine and you have a failure.

BB. · January 2014

Re: Newbie questions and.... help!!!

fordraceboy wrote: »

My power consumption for the building is fairly low, I have a freezer and a fridge/freezer, as well as fluorescent lights within the structure, and a few external lights. the freezer pulls 5amps and the combo unit pulls 11.2amps. 6- 4 ft dual T8 bulb shop lights and and 6-90 watt incandescent floodlights. The shop lights are used about 2 hrs a week and the floods are nighttime motion sensor only, so maybe 1-2 hrs a month.

While items that are used just a little per day/per week are not usually a big issue--You still need take everything into account when planning the system.

Here's where I get confused with all these battery numbers- I know that I need about 16A @ 120v for 8 hours a day for appliances, then roughly 4 amps @ 120v for the lights.

Monthly total is approx. 3600 AH @ 120v, or 440,000 watts.

This tells me I need 120 AH a day, so I would need 250 AH of storage to keep from dragging the batteries below 50% each day. Now, keeping the thought process of having a battery bank with 2-3 days storage, I'll shoot for 700ish AH. I've read that 24v is preferred to 12v for simple maintenance, but I honestly haven't tried to figure out a 24v set-up.

I am debating between the Trojan L16RE-B or the Trojan T105RE. The L16's mean fewer batteries, less connections and less parasitic loss. Using L16's would require a minimum of 4 batteries... right?

It is easier to work with Watts first (typically at 120 VAC or 230 VAC for other countries) and hours of use per day... Using AH is a bit confusing as you need to keep making conversions for every point in the system (120 VAC, 12/24/48 volt battery bank, Vmp-array for your solar panels, etc.). Watts and Watt*Hours are "universal" across every point in the system (plus wiring losses/conversions efficiencies).

So:

16A * 120 volts * 8 Hours = 15,360 WH = 15.36 kWH per day
15.36 kHW per day * 30 days per month = 460 kWH per month

That is not a "small system"... That is more than enough power for my suburban 3 bedroom home in a moderate climate with natural gas (20 miles south of San Francisco California).

A "small system" (no refrigerator/washing machine--Just some lights, radio, cell charger, TV, etc.) would be ~1kWH per day.

A "small system for an energy efficient full off grid home (add refrigerator and well pump, plus washing machine) you are looking at ~3.3 kWH per day.

I'd like to be able and expand this system to about double the above mentioned capability, given that I can keep up on the charge in the battery bank. I figure if I can keep the smaller one charged, it's a matter of adding input to compensate for the drain- I'd just like to know how much input that's going to take given my location.

You can, roughly, about double the output of an existing off grid power system (double batteries, double solar array, etc.)--But that is about it... Typically, you will have to virtually "start over" to go larger. And if the first system was already "pushing" the limits (i.e., around 2,000 watts peak output on a 12 volt bank), you will need to just to 24 or 48 volt battery bank (new inverter, new batteries, etc.).

Opinions on the batteries? Will I be better off to go 24v initially, or just upgrade later if feasible? How many solar panels am I looking at?

It is math that will give you those answers... Just a "real quick" nominal design to give you an idea what your first pass of AC power usage would look like:

15,360 WH per day * 1/0.85 AC inverter eff * 1/48 volt battery bank * 2 days of storage * 1/0.50 max discharge = 1,506 AH @ 48 volt battery bank

That would be around 32x 6 volt @ 435 AH L16 batteries (8 series * 4 parallel strings).

4 * 435 AH = 1,740 AH @ 48 volt battery bank... We recommend 5% to 13% rate of charge. A "nice nominal" rate of charge is 10% or greater:

1,740 AH * 59 volts charging * 1/0.77 panel+controller derating * 0.05 rate of charge = 6,666 Watt array "minimum" based on battery bank size.
1,740 AH * 59 volts charging * 1/0.77 panel+controller derating * 0.10 rate of charge = 13,332 Watt array "nominal" based on battery bank size.

And the mount of sun--In much of the US, 4 hours minimum sun per day will get you through 9+ months of the year without needing a genset:

15,360 WH per day * 1/0.52 end to end system eff * 1/4.0 hours of sun = 7,385 Watt array minimum

In the end, you are looking at 32*L16 batteries plus a 7,385 Watt to 13,332 Watt solar array to start your solar testing plans. Or very roughly, around $20,000-$30,000+ minimum in hardware costs.

Batteries will last around 5-7 years (can be more, can even be less if you have some early mistakes in running your system). Electronics, you should plan on replacing your inverters/charge controller/etc. about every 10+ years.

I like this windmill, does anyone have any experience with them? Better options for low wind areas? (I'm not in a high wind area, although my house is on a ridge so I can get some pretty harsh gusts)

The system you are looking at is on the small size. If it works "well", you can expect maybe 10-20% of rated output power (at best) in most locations/conditions (i.e. 90-180 watts average). Or the equivalent (4 hours of sun per day) of 540 watt - 1080 Watt solar array. Maybe 1/10th of your power needs (all things being equal, which they rarely are).

Wind power goes with the cube of the wind speed... Most turbines begin to produce a "tiny" amount of power at 10 mph. At 20 mph you have, literally, a 1,000 times more energy in the wind. If you do not have much wind--There is not much you can do. It is like placing a solar panel in the forest--It will generate almost no power at all.

Gusts are not going to give you much power and will simply damage your hardware. You may have better winds higher up--I.e., 60-90 foot minimum tower (commercial are 125+ foot towers). Turbines do not cost much money--It is the towers, support equipment and maintenance costs that are expensive (do you have to rent a lift truck/hydraulics/winch to access the turbine for maintenance every year?).

My suggestion--Design/build out your system based on solar and diesel/gasoline/propane backup genset. Once you get that stable, then you can look at wind.

Combination charge controllers? battery bank monitors?

Most of your choices are very dependent on what your loads/system capacity will be... I.e., if you need a 300 Watt TSW Inverter -- Your options are quite limited.

If you need 4-6kWatt or more, then you have a whole bunch more options/features to look at for Inverters/AC Chargers/etc...

I have a growing interest in this, but unfortunately, can't seem to find easy to decipher info, as it's all greek to me.

Don't try to drink from the fire hose... Take it a step at a time. Measure your loads, a Kill-a-Watt type meter is cheap and will be very informative (for your plug-in loads).

And, for a successful conversion to solar/RE power--Conservation will be your friend. It is almost always cheaper (and a better return on your investment) to conserve power than it is to generate more power.

Look at the cost of off grid solar power to be in the range of $1-$2+ per kWH (some do it for less, sometimes it cost even more). That is about 10x the cost of most people's utility energy today. If your utility bill went up by a factor of 10x -- What would you do around the house today? Many people who have never tried conservation before have found they can reduce their energy usage by 1/2 without impacting their daily life very much.

Energy usage is a high persona set of choices. We are not here to criticize those choices--Just to help educate so you can make a new set of choices based on your needs.

-Bill

techntrek · January 2014

Re: Newbie questions and.... help!!!

BB. wrote: »

...maintenance costs that are expensive (do you have to rent a lift truck/hydraulics/winch to access the turbine for maintenance every year?)....

-Bill

You have to tilt the tower or scale the tower every 6 months.

fordraceboy · January 2014

Re: Newbie questions and.... help!!!

Lots to ruminate on... I lose power for anywhere between 7-20 days a year, and was thinking of a viable alternative to my generator.

Looks like I need a kill a watt meter and get a good handle on actual usage. I'm not looking for a cost savings necessarily, more for power reliability. Any costs off my grid bill are just a plus.

BB. · January 2014

Re: Newbie questions and.... help!!!

Just to correct my math:

The system you are looking at is on the small size. If it works "well", you can expect maybe 10-20% of rated output power (at best) in most locations/conditions (i.e. 90-180 watts average). Or the equivalent (4 hours of sun per day) of 360-720 watts worth of solar panels. Maybe 1/10th of your power needs (all things being equal, which they rarely are).

Should have been a factor of 6x more power than solar (4 hours per day of sun vs 24 hours per day of variable wind)...

540 watt - 1080 Watt solar array vs a ~900 watt "good" wind turbine in a "typical" install.

Anyway--As you see, a solar power+battery bank is not a great investment for a few weeks a year of power losses. A generator plus backup fuel supply is a pretty good solution (assuming you can store fuel and the noise and fumes don't bother neighbors--such as the typical small lot in a city).

Otherwise, if you want to get started "small"... A 1,000 WH per day system is not bad (take the above numbers and divide by ~15). Use the small system for "quiet time" (evening/overnight) and use a genset for daytime/battery recharging (or backup for small solar array/bad weather).

You might even want to look at a couple gensets... A "small" inverter-generator type (Honda eu2000i/eu3000i or similar Yamaha inverter-generator) are pretty nice. Small, pretty efficient at lower loads ("regular" generators are not very fuel efficient below ~50% of rated output). If gasoline, use a fuel stabilizer and rotate the fuel out every year.

And a backup to the backup--A second noisy/fuel hungry/cheap 3-5+kW to run the shop tools/large saws/well pump/etc. when needed...

-Bill

mike95490 · January 2014

Re: Newbie questions and.... help!!!

Maybe a pair of 6V batteries wired for 12V, a 12V charger, suresine 300 inverter and a pair of eu1000 gensets is the way to go. Charge the battery, let it quietly run a couple lights all night, generator daytime to power the fridge and charge the battery.

techntrek · January 2014

Re: Newbie questions and.... help!!!

BB. wrote: »

...Use the small system for "quiet time" (evening/overnight) and use a genset for daytime/battery recharging (or backup for small solar array/bad weather).

You might even want to look at a couple gensets... A "small" inverter-generator type (Honda eu2000i/eu3000i or similar Yamaha inverter-generator) are pretty nice. Small, pretty efficient at lower loads ("regular" generators are not very fuel efficient below ~50% of rated output). If gasoline, use a fuel stabilizer and rotate the fuel out every year.

And a backup to the backup--A second noisy/fuel hungry/cheap 3-5+kW to run the shop tools/large saws/well pump/etc. when needed...

-Bill

Agree with all of this, this is similar to what I do with my backup-only system. I use a big Generac for a few hours a day for a well pump & electric water heater, and a much smaller fuel-efficient setup for the base loads (fridges) and the other stuff we use when awake (lights, TVs, wood stove fan, etc). I also have a Yamaha 2400 watt inverter-genset as my worst-case backup. I'd love to add a small PV system just for the base loads but the kid's college funds come first. If I had to do it all over again I wouldn't have purchased the Generac, I would have gotten a similarly-sized contractor screamer for 1/8 the cost. A self-fueling automatic genset is great for those short outages in bad storms where you sit on the couch and smile when it starts up, but the first long-term outage (like you get) and the smile disappears because of the fuel costs.

Originally I just had the big Generac and a 22 kw battery bank for overnight use. Since engines run most efficiently loaded around 70% I would put all the load on in the evening and then shut it down. But the hassles of the battery bank (watering, equalizing) and the replacement cost isn't justifiable with the availability of the inverter gensets. A grand or two up-front and then a couple of gallons of gas a day were cheaper and less hassle.

By dividing your loads up with different gensets you get the most function for the lowest cost. You also have a backup for your base loads if your smaller genset dies, by using your larger genset sparingly (2 hours on, 4 hours off). Just keep 20-30 gallons of gas on-hand at all times. I recommend swapping out your fuel every 6 months even if you are using Stabil - I learned by accident that year-old fuel runs fine in my Yamaha but it takes 10 pulls instead of 2 to get it started. That tells me the gas isn't as fresh as Stabil wants you to think it is. I've now changed to 6 month swaps.

BB. · January 2014

Re: Newbie questions and.... help!!!

Sad to hear about the 6 months change out--I would like to avoid that.

One of the reasons I get fuel in the winter is that (I believe) in California, there was less alcohol/oxygen (another scam) used in winter blends... Winter fuel was supposed to be more "stable". Also, we tend to get our worst storms in late December and beyond--Most likely when I will lose power.

I should get/convert a genset to natural gas--Have never lost natural gas, even in a major earthquake... But I keep the gasoline because of earthquakes and as a bug-out fuel for my vehicles--If ever needed.

Oh boy--Another test to run "someday" on my stored fuel.

-Bill

Cariboocoot · January 2014

Re: Newbie questions and.... help!!!

We don't have the mandatory ethanol blend up here (although it is available - for more money).

But this is why I do not 'store' fuel, I 'keep it on hand'. Since everything I've got (including vehicles) burns the same stuff, it's just a matter of keeping the jerry cans in rotation.

I'd be a lot happier if it didn't cost $5.24/gallon (U.S. equivalent), so whenever I go to Kamloops I (illegally) drag back containers full @ a mere $4.67 per.

Fortunately repeated medical needs have enabled me to stay ahead on the game, so to speak.

Sealed container, no stabilizer: it's still good for a year.

BB. · January 2014

Re: Newbie questions and.... help!!!

Storage temperature probably makes a huge difference too.

The old 10°C drop in temperature gives two times longer storage life.

Currently, my "cool" storage area is full of junk. I need to clean up.

-Bill

techntrek · January 2014

Re: Newbie questions and.... help!!!

BB. wrote: »

...

Oh boy--Another test to run "someday" on my stored fuel.

-Bill

Better to be the 1%.... that is prepared... than the 99% that isn't.

Newbie questions and.... help!!!

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