Have generator, will travel

This weekend, I finally got around to project that has been on my list for a while.  I moved the giant Kohler propane generator that was originally by the house. It's now over at the shop. We haven't used the Kohler since the early winter after we purchased a much smaller (2000w vs 12000w) Honda inverter generator.  The Honda is perfect for supplementing our solar energy in the off season.  The Kohler was just too big for us to run efficiently.  Even with full charge on the batteries and some house load, we were only using about 15% of the generator's capacity and still burning lots of propane (1-2 gals/hr).  With the Honda, we can set our charger to load the generator at about 75% of it's capacity  (regardless of house loads) and it still sips fuel (~0.25gals/hr).  We run the Honda a little longer, but it's works out well in our favor. As an added bonus, the Honda is a great complement to the Scamp -- it'll even run the AC.

So the Kohler will get re-purposed as a shop generator for running larger 240v power tools like my table saw and other large gems that I might come across on Craig's list.  I've been contemplating going this route for some time, but was reluctant due to the lack of propane over at the shop.  A quick call to our propane company, Montana Propane, cured my reluctance.  They offered to replace our existing 1000-gallon rental tank with two 500-gallon tanks at only the cost of parts for hooking up the second tank.  The even cut us a deal on the rental price for 2 tanks so they come out to the same price as a single larger tank. Cass and I have been thinking the 1000-gallon tank was too large and obnoxious for our needs for a while anyway, so everyone's happy!

Water water everywhere!

Woohoo, our new pump is in! That's right, we had to break down and buy a new well pump. Unfortunately the old pump started giving us problems earlier this summer. It started shutting itself down due to "overload" and was getting harder and harder to get started up. The pump was super efficient and designed for off-grid living, but unfortunately I don't think it was installed correctly in the first place. I did a few calculations when we started having problems and it turns out the installers undersized the wiring pretty significantly so the voltage at the pump was probably too low for the pump's entire life. It lasted 7 years this way; not too bad, but less than I would expect from a $3000 pump. The pump is likely salvageable, but it is produced by a German company and getting local service for it is nearly impossible. Also, the thought of spending $500 on appropriately sized wire and needing to dig a trench for the new cable was enough to make me rethink the options.

The choice of submersible pump for the off-grid home owner should not be taken lightly. There are a number of options out there:

• Low Voltage high capacity pumps like our previous Lorentz or the Grundfos SQFlex are designed to run directly off solar panels or batteries.  They tend to very efficient, but the upfront cost for the pump, heavy wiring, and optional solar panels can be significant.  The other downside is that they tend to be more complex, or at least rarer, and finding someone to service them can be a challenge.  Since we only got 7 years out of our last pump, I wasn't willing to go down this road again.  
• Incorporating a cistern is often times a good option for off-gridders.  Cisterns can be filled using solar slow pump or a large gas pump if the water source is close enough to the surface.  We may get a cistern for summertime watering some day, but since we don't already have one -- and we needed water now -- we didn't really consider this as a viable option.  
• The other main option is more traditional 120V and 240V pumps.  There are a variety of models to choose from, they are available locally, and they are relatively cheap.  But, they use more power.  Off-gridders need to consider not only how much the energy it takes to run the pump, but also the amount of energy it takes to start it up.  

In the end, we went with a 240V, 1/2hp 10gpm Franklin pump.  Our well recharge rate is ~10 gpm and our old pump (at 6-7 gpm) was getting worked  pretty hard when irrigating the wind break, so 10gpm pump is a pretty good match. The new pump uses about 1400watts.  I'm not sure what the startup watts are, but our 3500 watt (6000 watt surge) inverter doesn't seem to have any trouble getting it going.  To reduce number of startups, we got a second pressure tank.  We now have two 45 gallon pressure tanks, set at 25-45psi, so we get about 25 gallons of water per pump cycle.  The pump will cycle quite often in the summer when we're irrigating, but only a few times a day in the winter when we don't have much energy to spare.  

So...are we going to regret the decision not to buy a super-efficient solar pump?  I actually don't think we will. We are most likely to regret the decision in the winter since that's when we have the largest energy deficit.  But in the winter we don't really use a lot of water. On a big day, we might use 100 gallons of water/day. Here is how much energy it takes pump to move 100 gallons :

• Lorentz solar pump: 100 gallons @ 7gpm = 0.238 hours of pumping * 500 watts = 119 watt-hours
• Franklin 0.5hp pump: 100 gallons @ 10gpm = 0.167 hours of pumping * 1400 watts = 233 watt-hours

Based on these numbers, the Franklin will use about twice as much energy, but...120watt-hours is really pretty insignificant in the grand scheme of things. One $300 solar panel would more than make up the difference.  The difference in price between the pumps is on the order of thousands! There was also an additional energy expense associate with the Lorentz pump.  Since we needed a 48v version to match our water needs and our system runs on 24V, we needed to incorporate a 24-48v converter.  This converter consumed 3watts at all times -- ~75watt-hours per day, so the realized difference in energy is actually smaller than the example above. With the new pump, we do need to run a 240V auto tranformer 24 hours a day, but I've been doing that right along anyway for power tools in the shop.   Once we can move the big generator over to the shop, I will likely rewire the transformer to run only during the pump cycles.

To make a long story short...No, I don't think we'll regret the decision.   

Adventures in batteries!

Well, the time for new batteries has finally come.  Our original batteries have been dropping off one-by-one and although they've been more than adequate throughout the summer (when the days are long and the clouds are few and far between), they have little chance of making it through the winter.  Our current batteries have lasted up to 6 years. I only say "up to" because some have lasted longer than others and some were purchased earlier than others.  I don't know all the details because I didn't do the purchasing. Had the batteries been taken good care of, we may have gotten 10 years out of them...but they weren't.  The previous owners did a number of no-no's associated with the batteries.

• No-no #1: They didn't really have a good idea how much energy they were going to use when they purchased the batteries. It turns out running grow lights uses a LOT of energy and their batteries weren't really sized to handle the demand. 
• No-no #2: When they discovered the battery bank wasn't big enough, they added more batteries in series instead of starting from scratch. Mixing old batteries with new batteries is always a bad idea.  Even if the batteries are of the same type, as batteries age the lead plates get thinner and thinner.  Even when the batteries are resting current flow from the new batteries to the old ones. The old batteries work harder than they should even when they should be resting and the new batteries get dragged down to the level of the old ones. 
• No-no #3: When they added the new batteries, they created 5 parallel strings.  The fewer string the better.  Five is a lot!  With five strings, an equalize cycle is required frequently to keep the batteries at similar state of charge (SOC).  
• No-no #4: They didn't know how to run an equalize cycle!  I asked the previous owners how often they equalized the batteries. I don't remember what they said, but I know the take home message was, "we don't".  

Given all of the no-no's, I guess 6 years isn't so bad.  At last not until you considered they spent about $7000 on batteries.  Ouch.  Lucky for us, we were able to learn from some of their mistakes.

So how did we go about deciding what to get for a new battery bank?  There are a ton of choices out there.  First, we needed to know how much power we use. This varies a bit, but on big days we are at about 3500wh/day.  The general rule of thumb these days is to get a battery that has about 4 times the amount of your daily requirement. This gives you about 2 days of autonomy if you keep your batteries above 50% SOC.  Traditionally, people planned for much more that 2 days of autonomy.  There has been a shift to smaller batteries as of late.  The logic for this has a lot to do with the price of renewable energy supplies.  The price of batteries has remained pretty stable over the years.  The price of solar, however has been going down everyday.  Since batteries don't last very long if they are undercharged, it just doesn't make sense to get a battery that is oversized for a charging system.  Batteries are rated in amp-hours (ah) -- at 24V (our system voltage), 3500wh/24V = 145AH. We use about 145AH per day from a 24V battery bank.  145AH x 4 = 590AH.  So, we were looking for a capacity of about 600AH.

I looked at a number of different options with the following in mind:

• 600 - 800AH capacity
• Lead Acid - I like being able to equalize and monitor the specific gravity of individual cells, so I decided against sealed batteries. 
• No more than 2 strings - preferably one.
• Long life
• Affordability

I finally decided on a forklift from Giant Battery I ended up getting a model 12-85-13.  Fork lift batteries are big and heavy, but can last up to 20 years with proper care.  The model I got weighed about 1100lbs.  Since it weighed so much, putting it in the crawl space was not an option.  Instead, we will built a small (2'x4') extension off the back of the house so we could move it into place with my neighbors backhoe.  The additional bonus of having it up and out of the crawl space is temperature.  Batteries perform there best at around 70F.  We were losing a fair amount of capacity by storing our batteries in the 45F crawl space.

The forklift battery at home in our new mini-extension. 

The new battery has been in place few a few days now. The installation went off without a hitch.  We'll see how it does this winter.  Time will tell!

Homestake Lodge: Spring Skiing, Off the Grid

For the B&B (Bill and Baxter) birthday party we packed  up our cross country skis for the final ski trip of the season. Homestake Lodge is a relatively newly-developed, off-the-grid, cross-country ski area just a few minutes east of Butte. The ski conditions were fair to poor, due to a long stretch of 50 degree plus days, but the trails look like they have great potential when the snow's good; they're narrow and winding. And best of all, we were able to take our dogs on the trails! Lodging (cabin or yurt) is dog-friendly as well. And up at the main lodge, there is hot soup and fresh baked bread available for lunch.

The owners, Chris and Mandy, are a couple from Maine who designed and built the trails and the lodge from the ground up. Chris was kind enough to give us a tour of his energy set up and solar hot water collectors; he had some good suggestions for when we put in our own. Tip: make the water collection tank as big as you can and place it near the panels for optimum heat conservation.

Bax, 12 today!, and Stew having a good day on the trails.

Bill water skiing across a melted portion of trail.

Both just happy to be part of the team.

Overlooking some of the trail system.

Toasty Warm Feet with Energy to Spare!

Stewie has warm feet too!

For the past couple of weeks I have been working on re-configuring our propane boiler to make our in-floor radiant heat more efficient. I have been pondering how to do this for quite some time. The problem is, the original water pumping system was very inefficient. In fact, using the propane boiler with the original pumps to heat the house roughly doubled our electrical usage. And of course we need the boiler at a cold time of year when we have the least amount of energy to spare. Up until now, we've used our wood stove solely to heat the house. But now we have the option for toasty floor heat too. Here's how...

Originally, the boiler was configured with 3 circulating pumps: one pump circulated water through the boiler itself, and the other 2 pumps circulated water through each of 2 zones in the house. Each of the pumps was oversized for our heating system - they pumped a lot more water than they needed to and each consumed ~85 watts for a total of 265 watts. Our hot water pipes are stapled up under our floor. Since the pipes aren't embedded in the floor, not very much of the heat gets transfered into the floor and much of it gets returned to the boiler. Since the heat transfer is so slow into the floor, there is no point in pushing the water through the pipes this quickly.

So, I started looking into some lower flow solutions that would use less energy. The first thing I did was calculate the amount of water we need to move. (Thanks to folks on the following forum for helping me out with the calculations: Terry Love DIY Forum)

BTU requirements:
We live in a cold area, but our house is extremely well insulated. Walls and ceiling are both > R40. Our house is 1300sq ft and is designed for passive solar (If it's above 0F, we don't need supplemental heat until the sun goes down). For my calculations, I used a heat requirement of 60,000BTU/hr, but I think this is definitely overkill.

Flow requirement:
The heating array is made up of (60) 30' lengths of 1/2" pex for a total length of 1800'. These are divided into 7 different loops of 257' each. Each loop is responsible for 8500BTU/hr. Assuming a 20 degree temperature drop, then the flow through each loop should be 0.85 gal/min. Total flow for all 7 loops combined is 5.95 gal/min.

Next, I needed to calculate how hard the pump would have to push (in feet of head) to move that much water through our pipes.

Head Calculation:
Assuming 0.03 ft of head per foot and a loop length of 257ft, the total head is 7.71ft. This only needs to be calculated for one loop. The fact that we have multiple loops in parallel doesn't mean the pump has to push any harder, it just needs to push more water.

So, I finally started shopping around for pumps. Three pumps for our system is overkill. There isn't much benefit in having multiple zones, and one pump can easily handle the whole system. The first pump I looked at was 24V dc pump from Ivan labs that we could run directly off our battery system: Ivan Labs El-Sid. The pump consumes about 10W but it doesn't move very much water: only about 3gallons per minute at 3 feet of head, so it would require 2 or more pumps to meet the needs of our system. At almost $300 per pump, the price was going to add up rather quickly. Finally, I stumbled upon the following article: Grundfos Alpha Case Study. This pump has multiple speeds, very low power consumption (15-45W) and our flow requirements fall right in the center of it's capabilities.

With a lot of help from folks online and a local plumber at R&R pumps in Helena I decided to dive in with both feet and do the installation myself. It took a bit of practice to get used to solder 1 1/4" copper pipe, but with a second propane torch and some help from Cassie we finally got the new pump installed. Last night was our first trial run, and...

IT WORKS!!!

The pump has a digital readout, so we can easily tell how
much energy it's using and how much water it's pumping at any time.

By installing the new pump, we lowered our energy consumption from 265W to 20W! That is 13 times less energy! Even if we ran the pump all day, it would only use 480W-Hours of energy. The previous setup would used 6360W-hours for a full day of use -- we don't even produce that much electricity on a good day in the winter. We are still in the trial stages -- I may need to push a little more water through the system to meet our needs, but I have the flexibility with this pump to do that if necessary. 

Here is what the boiler looks like now.
It looked like a rat's nest of piping before
the conversion too.  

We still don't really like the idea of heating with propane and will probably continue to primarily heat with wood, but it's really nice to have the option and know that we can leave the without our batteries dying and our pipes freezing. Eventually, we plan to install solar hot water heater. At that point we can use the same pump to heat the floors -- sans propane!

A battery monitor for Christmas? Just what I wanted!

Update:  Well, it looks like I did more damage than I thought.  The energy monitor worked for about a week. Now the numbers are all over the board.  I talked with Outback about getting it repaired.  They "might" be able to repair it, for 90% of the original purchase price. I've decided not to replace it with the same model.  I'm not a fan of black box electronics that are not repairable.  Instead, I'm going to build my own.  The electronics behind are actually relatively simple, the parts are affordable, and I can build it to my own specifications.  It won't integrate directly with my outback power system, but I will get over that part.  More on my progress later.

Original Post:

OK, I did not actually ask for a battery monitor for Christmas, but I am really glad we finally have one.  A couple of weeks ago we bought a Flexnet-DC battery monitor manufactured by Outback Power.  The bulk of our energy system is made by outback, so it seemed like an appropriate brand. 

Getting the monitor hooked took some work (and one rather significant mistake) but we finally have it running and collecting data.  I think I have mentioned before that not having access to system performance data has been driving me nuts.  This is only partly due to my own neuroses -- there are also valid reasons.  First and foremost is that fact that we will likely need to replace our battery bank in the next year.  The current batteries are dropping off like flies.   They have been undercharged for there entire life which is a common cause of premature failure.  Before we drop a few thousand dollars on new ones, I want to get a better idea exactly what we need so we don't make the same mistake again.

Hooking the monitor up turned out to be quite the challenge.  The original wiring was a bit of a rat's nest, so I took the opportunity to clean everything and make sure every wire had a purpose.  It was debatable on a few of them.   Overall the install went well, but I did make one significant mistake.  On connecting the windmill back up to the battery, I shorted the wrench across the battery leads.  This seems to have rendered one of the three monitoring ports useless - a major bummer.  What it means overall is that I can't monitor the wind mill and solar separately.  I can live with that.  I didn't cause any more damage than I think.

So what have we learned so far?  Well, the windmill has been burning about as much energy as it has been creating.  The problem is, it has a dump load connected to it so the batteries don't get overcharged.  Well, the charge settings for the solar are high enough that they trigger the wind mills dump load even if there isn't any wind.  I talked to the wind mill manufacturer about it.  They recommend disconnecting the dump load, so I'm going to give that a try.  The wind mill has an alternative mechanism for avoiding overcharge - it slows itself down.  Between that and the fact that I have never seen the wind mill come close to over charging the batteries makes me pretty comfortable running without the dump load.  The monitor has only been active for a few days.  We'll see what else we learn as time goes on.  

How We Get Our Energy

Well, we're one year in and...we've learned a lot and we're not ready to give up yet.  I must admit, the engineer (a.k.a. geek) in me has really gotten a kick out of studying and maximizing the efficiency of our energy system.  There are several ways to survive/thrive off-grid.  Here are few in no particular order:

1. Hire a company to design/maintain a state-of-the-art renewable energy system designed to meet all of your needs.  
2. Buy a lot of propane.
3. Scrape together what you can to get by and go to bed when the lights go out.  
4. Use less energy.

Most people I've met that live off-grid in Montana do a combination of #2 , 3, and 4. Not many people get by completely with number 1. The people we bought the house from tried to get by with #1 and a fair bit of #2.  They bought a good system.  Unfortunately it wasn't designed very well for them and they never really embraced the idea of energy conservation.  I feel like we've done pretty well on the energy conservation side things (more on that later).  We have also learned that you're better off learning how to maintain your system yourself than relying on any company to take care of it for you.

So here are the nuts and bolts.

Energy Producers:

• Solar: We have ten 150w solar panel with a total energy producing capability of 1500w in full sun. They are mounted on a stationary pole and no, they don't "track" the sun.  We could add a sun tracker and may at some point.  The concern is that it may be more trouble than it's worth since we get so much wind.  

• Wind:  We have a 1000w Bergey wind turbine.  Bergey is a reputable company, but the wind turbine never really functioned properly for the first winter of use.  It produced very little power and was extremely noisy.  Enough so to keep us awake at night.  By spring, the power production dwindled down to zero and we knew that it was time for maintenance.  With longer summer days (and plenty of solar input), we opted to lower the tower in May and perform repairs over the summer.  Turns out the rectifying unit (the part that converts the AC to DC current) inside the wind generator completely burnt up.  The turbine blades were also in need of replacement.  We contacted Bergey and they replaced all parts under warranty.  We finally raised the tower again last week.  So far it runs like a champ and is a lot quieter.  It will be nice to have this winter.    

I suckered a group of friends into helping me lower the tower.
We got the tower about 10% of the way down before raising
the tower back up and running away with our tails between our
legs.  100' is a long way up!  Some things are better left for the professionals.  

• Generator: Kohler 12 kw propane standby generator.  Our goal is to use this as little as possible, but some use is unavoidable.  Having enough solar and wind to account for every day of the year in Montana is an expensive proposition.  A more realistic solution is to size the system to meet your needs for the majority of the year and use a generator to get you through the darkest of days.  Last year, we used our generator about a total of 75 hours.  Just for comparison, the previous owners put 3500 hours on it in roughly 4 years.  That was after they burnt up their first (undersized) generator.  The generator comes on automatically when then batteries get down to a certain voltage.  Once it comes on, it generally runs for a couple hours and shuts itself down after the batteries get back into a comfortable range.   

Energy Storage:

Batteries and lots of 'em.  (This part gets a little technical.) When we first moved in we had twenty  6-volt batteries. Each battery has about 400Amp-hours of storage.  To put this into perspective, an average car battery has about 100 Amp-hours of storage.  Since our batteries are 6-volt, however, it takes 2 batteries, wired in series, to make a 12-volt circuit with 400Amp-hours. So, 2 of our batteries have about 4 times the amount of storage as a car battery -- we have 20.  However, since our system is designed to run at 24-volts, it actually takes 4 batteries wired in series to make a single 24-volt circuit.  Since we "had" 20 batteries, we had 5 sets of four batteries, each set was wired in parallel which increased our total capacity to 5 x 400 = 2000Amp-hours (or 48,000 watt-hours). What does this mean?  Well, since we use about 4000 watt-hour per day, we should have 12 days of storage, right?  Nope!    

• Problem 1:  Batteries should stay above 50% at all times.  That drops us to 6 days.
• Problem 2:  Batteries like to be fully charged every day or at least every few days.  We don't generate enough power to charge that many batteries.  Here are all the details if you want to know why.  

So we have lots of good batteries, but because they haven't been taken care of, they are dying young.  Based on my recent calculations, our current system and our needs, we are much better off with only 8 batteries.  I am in the process of pairing down our batteries to the best 8 and we will give that a try for a year.  Hopefully we can keep them charged and make them last a little bit longer.  A few of the batteries have already expired.  The rest we will keep in storage, and charge a couple of times of year, cycling them into duty as other batteries die. Eight batteries should give us roughly 2.5-3 days of storage.  We rarely have a 3 day period where the sun doesn't come out or the wind doesn't blow.  Even if that happens, that generator will come on automatically anyway.  We can live with that.  

Energy Use:

Since our batteries are wired for 24-volts DC, do we need 24-volt appliances?  Nope. Our house is wired just like everyone else's, with both 120V and 240V AC outlets.  Two, 3500-watt inverters convert the electricity into AC current.  Having 7000 watts of capability means we have roughly 50 amp service.  Most people who are connected to the grid have 100 amp or 200 amp service.  To be honest, we rarely use more than 1000 watts at any one time, so this really isn't a problem for us.  It does mean I can't run woodworking tools with large motors, but that's about the only downside so far. 

Energy Conservation:

According to the U.S. Energy Information Administration, the average American household uses about 29kw hours of electricity each day.  We don't really have a good monitoring system, but we estimate the we average about 4 kw/day.  We are going to invest in a monitoring system as soon as we can fit it into our budget, so then we'll have a much better idea.  Here are some steps we've taken to lower our energy usage:

• Lighting: All of our lights are compact florescents and we turn them off when we're not using them.  In the grand scheme of things, lighting accounts for a very small percentage of our total energy usage. 
• Deep well water pump:  We have a very efficient water pump for our well that runs directly off our batteries.  Although it doesn't have very high capacity, it meets our needs and uses very little energy.
• Refrigeration:  Our refrigerator and freezer are certainly unique.  A standard stand-up fridge uses about 2000watt-hours per day!  This varies widely.  If you're interested in lowering your energy usage, take a good look at your refrigerator.  We don't have a stand-up fridge.  Instead, we use a chest-freezer and regulate the temperature using an external thermostat designed for beer coolers.  Packing a chest freezer took a little getting used, but the benefits in energy savings are significant.  Freezer are inherently well insulated and since the door is on the top, the cold air sinks to the bottom when the door is opened.  In a stand-up fridge, much of the cold escapes when the door is opened.  This freezer-converted-to-fridge design uses about 300 watt-hours per day.  We also have a solar-specific chest freezer. It is super-insulated and runs directly off our batteries.  It runs on about 600 watt-hours per day.  So, we use under 1000 watt-hours per day on refrigeration, with a lot of food-space capacity.
• Space Heating: First of all, our house is very well insulated.  A central wood stove easily keeps the house in the 60's even on the coldest of winter days.  The house is equipped with in-floor heat, powered by a propane boiler, but so far we haven't used it very much.  Firewood is plentiful and we just don't really like the idea of burning propane if we don't have to. We used roughly three cords last winter to keep us warm and happy--not too bad for a Montana winter. In the long run we are hoping to incorporate some solar hot water heaters.  If we design it right, we will be able to pump the hot water through the floors on sunny winter days.  
• Water heating:  We have an on-demand propane hot water heater.  The on-demand aspect of it is efficient, but we hope to limit our use of propane once we install solar hot water heaters.   We also hope to install a hot water heating coil in our wood stove which will help distribute the heat through the floors. 
• Cooking:  Our stove and oven are propane.  OK, not really energy efficient, but we sure like it.  This is a luxury that we are unlikely to give up. 

Otherwise, we live pretty much like everyone else.  We have a computer (with satellite internet), a big screen TV, and most modern appliances.  We are a lot more conscious of the energy we use and both like that aspect of it.  We also feel like we are much more in tune with the weather and what's going on outside.  It's been a great experience so far!

Why Blue Cloud "Power Co"

In October 2010, Cassie and I purchased a house in central Montana.  This wasn't just any house.  It situated on 15 acres and is about a mile from the closest electrical pole.  This doesn't sound like much, but as far as the power company is concerned, it might as well be 50 miles.  Blue Cloud Creek runs right through the middle of the property.  We are told the creek rarely runs, but been flowing like gangbusters for the last couple of months.  Although the house is far from the electrical grid, it came well equipped.  The previous owners built the house in 2006 with the intention of growing medical marijuana plants here.  Growing plants in Montana (and without a greenhouse) takes a LOT of power.  They took this into consideration when they built the house and install a solid off-the-grid electrical system.  The system came equipped with solar power, an already aging wind turbine and an overworked propane generator.  Even though they bought good equipment, they had a few things to learn about maintaining it.  

More to come, promise.