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Ask Jeff Yago
Solar & Energy-Related Issues

By Jeffrey Yago, P.E., CEM
Jeff Yago


Electric automobiles that use no fuel

Sirs;

My desire is to... Create a family TOWN CAR or SPORTS CAR that looks like something, no-one would be ashamed to be seen in.

(the reason so many electric autos fail)

Something looking like a Lincoln Town Car or Ford Mustang, would start like a regular car... in that one would turn a key, which powers a starter, in turn cranking a flywheel... but that is where everything changes.

The flywheel turns a generator which creates electrical power... the generator powers the electric motor, which then turns the generator, disengaging the starter. As you drive, your motor turns the generator, which in turn powers the motor, and all the necessary electrical appliances within ones auto. There is no need to charge the battery (other than the regular charging like ones gas car would) because it uses the same amount of battery power (only to start) your present (gas powered) car utilizes.

I also heard of a BIO-diesel motor, powering a generator, that runs electric motors... etc. This I also agree with... but why need the Diesel if you can do it all electrical? One asked... what if the electrical motor or generator fails? My response? What happens if you over heat your Gas motor? Answer? Exactly the same thing, you get towed to a repair facility or dealership.

Now do the same thing, with an electric generator at ones home, continuity controlled by a computer chip.

(continuity controlled... means when a refrigerator or air conditioner cranks up, it makes the generator slow some as it handles the extra pull... perpetuity means the electric motor would also slow... adding less power to the generator... slowing the turn of the motor... and eventually the motor/generator combo would come to a screeching halt.) The chip would add speed to the motor until the household devices cease to require the added power.

Now that I have given away my idea... what do I do, whom do I contact... Why Won't it work?

SFC Terry Wilcox
US Army Retired

Terry,

The reason electric cars have not done well is not their looks, its the fact that most can only go 40 miles before needing hours of re-charge. Not exactly practical unless you live less than 20 miles from work, stores, schools, ect. Its like owning a gasoline powered car that has a one gallon gas tank - not a relaxing way to travel! The hybrids partly solved this by haing a small motor for highway and the electric motor for slow stop and go in the city.

As for a motor turning a flywheel, that turns a generator, that generates the power to run the motor, that turns the flywheel, that turns the generator, that generates the power to run the motor, that........................

You see the problem?

See if this helps you understand the problem. Find somebody that can lift up to their own weight. Lets say they weigh 140 pounds and they can lift 140 pounds. Now have them bend over and grab their ankles. Now lift themselves off the ground and volia. A human powered helicopter that requires no engine!!

How about taking a 26" boys bicycle and remove the front wheel and replace it with a smaller 20" wheel while leaving the larger rear wheel in place. Then the bicycle rider would be going downhill all the time and you would not have to pedal!

As you see, you cannot extract work or power from any device without adding more energy than it requires to run due to friction. It makes no difference if it runs on a battery charge, sunlight, nuclear fusion, wind-up spring, steam, gasoline, diesel fuel, or compressed air. Just as soon as you remove the external energy source or when it is used up, the device will run down and stop. Period. Now if you are in space, and fire your rocket motor for a few minutes the turn it off, you would coast all the way to the stars without any more power, because there is no friction or gravity to hold you back or create drag.

Sorry, but these schemes have been tried since they invented fire and you just can't get around the laws of physics, at least not while standing on the earth!

Jeff Yago


Deep well pump

Hi,

I am looking for a 1/3 HP four wire deep well pump. I live in Benicia California.

I have a cabin in Vanderhoof B.C. Canada. I have no electricity. I have a generator, Trace invertors and solor cells with 12 deep cell batteries. The well is 119 feet deep. I have about 70 foot of water in the well..

I have a 1/2 HP deep well pump for my well. This takes too much electrify and I have had many problems with it.

Can you help me?

Thank You

Terry Baxter

Terry,

With 70 feet of water in a 119 foot deep well it appears your pump will not require too much lift unless it is a very slow recover well and the water level dumps down so you may be able to get by with a 1/3 HP pump. However, I suggest another approach. Have you considered replacing with a D.C. voltage pump. I do not know your system voltage, but based on your battery count I assume it is either 24 or 48 volts.

Dankoff Solar (now Conergy) in New Mexico makes and distributes several excellent D.C. powered well pumps in both submerged and above ground versions. They are not cheap, but this will power the pump directly from the batteries and would put no load on the inverter. The link below will describe their smaller pump which is good for up to 165 foot lift and 9 GPM, and requires only battery or solar power - no inverter.

http://www.conergy.us/Desktopdefault.aspx/tabid-159/226_read-1797/

You should be able to also find this pump at several solar retail outlets using a search for "Dankoff Solar Pumps". You should also search for "Solar Jack" brand pumps. I have had one in my well for over 12 years. Solar Jack pumps usually have a lower flow rate than the Dankoff pumps, but they are also less expensive and do not require an above-ground power conversion control which is used with some models of Dankoff deep well pumps. The SolarJack pumps use a diaphram that moves up and down by electro-magnets instead of a more typical rotating impeller, which results in a "pulsed" water.

Good luck!

Jeff Yago


Hooking up solar panels

Dear Jeff,

We have solar panels, an inverter and the battery. How do we hook it up through the 110 breaker box.

Thanks,

Betty

That depends on many things you did not mention. If this is a large inverter like an 2,000 watt Outback or 4000 watt Xantrex, then they include labled terminals to make this connection and excellent diagrams in their owners manuals.

If this is a small inverter like those handheld 400 to 800 watt inverters sold at Sams or Costo, then I would not connect it to a house electric panel since they usually include a duplex outlet and are not designed to be hard wired to a multi-circuit panel.

You do not say if this is an off-grid application, in which case the breaker panel you mention may be the only electrical panel, or if grid connected, this will probably be a "sub-panel" that only powers a few emergency loads like a refrigerator and a few lights. Each of these system types require a different way to make this connection.

I strongly suggest that you contact a licensed electrician if you are trying to make any wiring connections to an existing grid connected 120/240 volt circuit breaker panel in your home, as this can be very dangerous if you do not know what you are doing.

If you need a more specific answer, you need to provide more description of your system, if on-grid or off-grid, inverter model and size, types of sizes of all electric loads you want to power with it, is there also a backup generator, and will it operate year-round or only during a power outage.

Jeff Yago


Make lead-acid batteries

Hi Jeff.

After finding out the prices of large lead acid batteries, and reading up, I am wondering if its feasible to make a battery at home. It wouldn't need to be small or portable as it could be build in place - I picture something like six plastic garbage bins (in an outdoor shed!) with chunky molded lead electrodes. Can you tell me what surface area of lead would be needed per Amp/hour? Any other comments you have would be much appreciated.

Thanks in anticipation,

Peter

Peter,

If somebody had a way to mold the lead plates I guess it is possible, but I would not recommend it. First, its not just lead "chunks" hanging in a plastic tub of acid. The plates are formed with a deep waffel pattern molded into the surface to increase the surface area in contact with the acid. This means a square foot of plate may actually have several square feet of surface in contact with the acid, and the amp-hour capacity of any battery is directly related to this surface area.

Please also note the plates are not the same type of lead, so unless you have some way of lead manufacturing, I am not sure how you can make the plates. The negetive (-) plate is called "sponge lead" which is pure lead (Pb). However, pure lead is too soft to hold its shape so other compounds are added. Some of the items added to the pure lead will lower the water loss during charging and some can reduce the standby discharge loss.

The positive (+) plate is lead dioxide (PbO2). The lead dioxide forms lead sulfate (SO4) and water during discharge, and this turns back into Sulfuric acid (H2SO4) during charging.

Almost all lead-acid batteries made today fill the waffel pattern with a special "paste" which also increases the surface area. The positive and negetive plates are alternated near each other and separated by a glass matte that keeps them from making electrical contact but allows the acid to make contact.

There have been many battery explosions caused by the positive and negetive plates making electrical contact and shorting out, or by a poor connection at the top of a plate causing an arc where it connects to the top buss bar of the terminal post which ignited the hydrogen gas that is produced during charging. Other battery failures are caused when the sulfate builds up at the bottom and shorts out the plates.

Good luck with your project, but be sure to stand really really far away when you connect the charger!!

Jeff Yago


Generator amp sizing

Jeff,

I am a ME who designs PV systems. My company also sells generators [becasue] we frequently use them in our stand-alone systems. We constantly get asked to design and sell a generator [without] a PV system to provide backup power for commercial and residential applications.

My question is about Amp sizing. I have done some research and we have an EE and Architect on staff. We all have our own opinions, including the manufacture of the generator. Are there any publications you would recommend we could reference?

Thanks,

Mark Rangel, GM/ME

Mark:

This is a REALLY big subject right now as there have been several recent changes to generator designs to meet higher EPA emission restrictions that were not good for off-grid PV systems. First, there is a difference between residential and commercial applications which you mentioned. Residential sizing is usually based on what the client can afford, not what you feel the perfect size should be for the loads. Once this has been decided, the inverter is programmed not to over-load the generator (if there is an inverter), or a sub-panel is installed with a mix of the most critical loads that will not exceed the generator capacity. Most times this ends up being a trial-and-error adjustment after installation!

Unfortunately, generators do not act like the utility grid, and when you have several very large kW loads that will be on the same generator, it is very possible to overload the generator even when their total kW load is far below the generator's published ratings. I have had this problem on emergency generator systems I have designed for hospitals. This is a real problem when one of the loads is much larger then the other loads.

The ideal generator loading is lots of small loads with only a few having a high inrush startup current like a refrigerator compressor, AC unit, or well pump, since the inrush on these motor loads can easily double the run load current If this large motor load is the only load on the generator at the time, it will usually cause a voltage drop for a few seconds during the brief current surge then go back to normal without a problem. But when this happens while there are other loads being supplied, this can cause problems for any generator that is not sized much larger than the maximum loads that will be connected. When dealing with several large loads, you may need more than 50% excess capacity.

On large system applications, Kohler offers a good software program that is usually free from your local distributor, which will help you size a generator based on this mix of loads. It takes into account this issue of individual loads and not just total load requirements. I am not sure about other generator brands, but I assume they offer the same free design assistance. There is not much out there in texts I have reviewed.

Another big problem we have experienced is generator RPM ratings. We have installed 8.5 kW generators having 1800 RPM engines that have worked great for years on several off-grid applications. Then when we finally had to replace the aging generators, all you can find these days in smaller sizes are 3600 RPM units (Thanks EPA!!). When we replaced the older 1800 RPM units with the new 3600 RPM units, we had nothing but trouble related to tripping off line due to over-load and voltage range errors even though nothing else in the system changed. Same loads, same inverter, same solar array, same fuel, same nameplate ratings. It appears the lower RPM units had higher torque in the lower range which had a faster response time for large startup loads.

All of us are having major issues with generator manufacturers. My biggest issue right now is when you are off-grid, you do not want any "phantom loads" drawing down the solar batteries 24 hours per day. Older generator designs included a magneto in the flywheel or second windings in the starter motor that re-charged the starter battery when the generator was operating. Almost all of today's generator manufacturer's have dropped this battery re-charge feature and added all kinds of digital diagnostic panels, display panels, and oil heaters that you cannot turn off.

To avoid totally discharging the starter battery in less than 2 days from what can be up to 100 watts of constant load, they proudly include a separate battery charger that you plug into the nearest 120 volt grid connected wall outlet - Oh, you don't have grid power? Sorry.

Good luck, but right now you will find the back-up generator manufacturers are only interested in emergency back-up applications for grid connected homes that only need to run a few hours each year. They have no interest in the off-grid market, and are voiding warranties when the generator needs to run several days each week, every week of the year.

Hope this helps,

Jeff Yago


Saving energy in an older home

Jeff,

I am looking to change my current heating system in my home. I now have a converted oil to gas burner that came with the house and is at least 40 years old. There is still an oil tank in my home that is not used. My total gas bill for the year is about $2,400.00 which includes powering a separate 50 gallon gas hot water heater and gas stove. What are my options for change to include any alternative systems. I do currently have and use a fireplace in my living room. The house is a small two story colonial about 1,200 feet on each floor with a finished separate basement that is on a second zone.

I would love to move to something less reliant on Exxon and KeySpan. Thank you in advance.

Regards,

Craig

Craig:

Since you do not indicate the type of heating system you have, only the fuel, I have to guess and my answer may not match what you have. Since you said your home was over 40 years old and you had an oil system that you converted to gas, I bet you had an oil fired hot water boiler in the basement with a small electric pump that circulated hot water to baseboard radiators or fin radiation units under each exterior window.

I think switching to gas was a good move but you should contact your supplier to see if they offer any special rates. Most gas suppliers have a surplus in the summer and are willing to "fix" your winter rate at a lower cost if you pay a small fee. This is usually re-newed each spring or summer for the following winter.

The next thing I would do is check into a higher efficency boiler (or furnace). Even though you switched the burner from oil to gas, most 40 year old boilers were only about 70% efficient at best, and most new boilers are over 90% efficient. Also, if you have ducts or hot water heating piping running through an un-heated basement or crawl space, these should be insulated, but if they are over 40 years old they may be due a replacement.

Finally, I would add as much insulation as you can get into the attic as this is a major heat loser for most homes. Many older homes do not have any insulation in the exterior walls, but usually do not have any void that can have insulation added today. For older homes most of their wall heat loss is by air infiltration. Installing double pane insulated windows and re-calking around all exterior joints, windows, wall outlets, and doors will greatly reduce exterior wall heat losses when you cannot add new insulation. Regardless of cost, most investment in new insulation and calking will save far more than their cost.

Good luck,

Jeff Yago


Wood stove to heat water

Hi Jeff,

Here's my question. We are renovating and old victorian and we would like to install a very energy efficient wood stove that also has water heating capacity. Do you know if such a thing exists and could you recommend a brand? Even if it just heated water for domestic use (showers, baths, kitchen use) that would still be interesting to us.

Also, forgetting the water heating question, can you recommend a very high quality energy efficient wood stove for a small house?

Thanks, Anni Crofut
Massachusetts

Anni,

There are many good wood stove brands out there and many advertise in Backwoods Home magazine. Back in the 1970's when switching to wood stoves was the new "in" thing during several oil "shortages", just about anyone with a welder was making and selling wood stoves. Some were very good, some were junk, and a few were even dangerous.

Today, the market is mature and very competitive, so almost all of the inferior brands and their manufacturers have gone. Yes, there are still different levels of quality construction and materials, but most of this shows up as higher cost for higher quality even from the same manufacturer so you will get what you pay for.

As for wood-fired heating water - thats a different story. Unlike heating the air around a wood stove, heating water makes the wood stove into a boiler device and these can explode! There are few wood stove makers that offer a water heating "coil" as an option to their wood stove, but many have stopped due to liability issues. Although these can be made quite safe by installing the proper safety devices including properly sized pressure relief valves, temperature relief valves, and expansion tanks, many were not installed properly or lacked one or more of the above safety devices.

There are few manufacturers of small wood fired boilers just to heat domestic water (bath, shower, kitchen), but most wood fired boilers being marketed are designed to heat both the house and domestic hot water and are located outside the home, with the hot water piped into the homes heating and hot water system by insulated piping. These units are very efficient, but the downside is having to fire a boiler in the summer just to have hot water.

Most of these units are very good and safe since they are sold as a complete self-contained "package" and come with all required safety features factory installed. You can also find these advertised in this magazine.

Any hot water boiler should be installed by a licensed plumbing contractor regardless of fuel used, and include all of the safety features required by the manufacturer.

Good luck,

Jeff Yago


Running a well surface pump from solar

Hi Jeff,

I am new to solar and am only interested in powering one thing. The surface pump on my well. It is 220v and I have no idea what I need to run it. The internet has a plethora of confusing information. Can you help please??

Thank you,

Sarah Worley

Sarah,

I would need more information to answer this, but will give some general rules. You do not say if this is the only load because it's a pump out on a hill pumping water for cattle, or it's the only load in your house that you want to power when there is a power outage. You also say "surface" pump so not sure if you mean the pump is at ground level and only has to "draw" water up from a few feet of elevation like a pond, or this is a jet pump that requires a flow up and back down a deep well, and all require a different approach.

1. First rule, if this is stand-alone system like pumping water at a remote well for filling a tank and the wires to the house are too long, I would purchase a 12 or 24 volt DC "solar" pump wired to pole mounted solar modules. This type pump is expensive ($900 - $1600 depending on depth of well and flow required), but you would not need to buy an expensive inverter and batteries to convert the DC solar power into 220 volt AC. Also, almost all DC "solar" pumps are extremely low energy design, and most standard 220 volt AC pumps are very in-efficient and also have very high startup amp loads which is very hard on all but the largest inverters.

2. If this is part of your home load, then it does not make economic sense just powering this load. You would need a large solar array, battery bank, charge controller, and inverter to power a load this large. However, the system I just described could easily also power most lights in your home and maybe a refrigerator or TV. Of course, as you add these loads the battery would drain down faster, but you would not need any larger inverter as it already will need to be up-sized to handle the large starting current for the well pump.

3. Most low cost well pumps are 220 or 240 volt AC design as this allows much smaller wire size (and cheaper!) for the wire run from the house to the well, and lower-cost construction of the pump (and cheaper!)than a 120 volt AC design. However, most pumps can be ordered in a 120-volt version. The problem is all AC inverters have a 120 volt output, which means you will need two inverters to produce 220 to 240 volts or a step-up transformer, either are a very expensive solution to keep from buying the right pump in the first place!!

Hope this helps,

Jeff Yago


Charging Batteries

Jeff,

I'm very new to the world of alernative energy and need to power some equipment in a remote location. I don't need massive amounts of power and at the moment I'm trying to find the best configuration for my system.

As I understand it, whatever power is generated by my wind charger and solar panels, will be applied to the battery for charging via the charge controller. Is there a specific configuration in which the solar panels should be wired to optimize the charging? In other words, does higher Amps or higher Voltage charge the battery better?

Hope you can help.

Ursula

Ursula,

Good questions! To give you the perfect answer for your specific application would require more information than you have provided, but I can provide some general guidence.

Its not amps and its not volts, its both. The battery energy is stored as amp-hour capacity. For example, forget voltage for a minute and say you have a light that requires 5 amps of current flow when operating. If your battery has a 200 amp-hour nameplate rating when fully charged, and you do not want to discharge below 50% to extend battery life, this means you have 100 amp-hours to work with (200-100). Given this, your light would operate for 20 hours (100/5).

Now the volts - all this assumes the battery, solar array, and loads are the same voltage, so if your light is 12 volts D.C. and the battery is 6 volts, this means you need 2 batteries wired in series (6 + 6), but this does NOT increase the amp-hours! Using our example above, two 6 volt batteries of 200 amp-hours wired in series results in a 12 volt battery source of 200 amp-hour capacity! However, the voltage doubled.

Think of amps as gallons of water going through a pipe and voltage as the pumping pressure. On the charging end, the charge controller cannot "move" more solar energy from the solar array to the battery unless the charging voltage is higher than the battery voltage (cannot pour water from a lower bucket into a higher bucket without "raising" it up). When the solar array is a higher voltage than the batteries, and the charge controller is designed to "match" the battery voltage, you will end up with more energy into the batteries.

Actual energy load on any energy source is measured in watt-hours or kWh (1000 watt-hours). A "watt" is 1 amp of current at 1 volt, so a 100 watt light bulb requires the energy of about 0.9 amps at 120 volts, or 2.1 amps at 48 volts, or 4.2 amps at 24 volts, or 8.4 amps at 12 volts - its all the same amount of "energy" as for each case you get 100 watts when you multiply the amps times the volts.

The system voltage has a large impact on system losses and wire sizing. If your system was designed around a 48 volt DC battery, the wire size to carry the same energy flow at 12 volts would be much larger, and the wiring resistance losses would be over 4 times as great (48/12).

Hope this helps and suggest you check some of the back issues where I discuss this in more detail.

Good luck with your system layout,

Jeff Yago


What tells the pump to turn on?

Hello my name is Guy Smith would like to know if the signal for a solar hot water system pump to run and circulate is a photo cell or temp sensor. It is located on roof near collectors and recently pump hasn't run.

I have an Independent System Manager controller model C-100 and was wondering if it is what tell's the circulating pump to turn on? I appreciate any info. and hope it is understandable.

Again thank you very much.

Guy W. Smith

Guy:

Almost all solar hot water systems are controlled by a "differential" temperature controller. You should see 2 sets of terminals, one marked "solar" and one marked "tank", in addition to 2 terminals or a plug-in outlet for the pump. This controller does not measure sunlight like a photocell or understands anything about the sun. All it does is measure the signal from a temperature senser attached to the piping inside your roof-mounted solar panel, and compares this with the signal from a temperature sensor attached to the exterior of your hot water tank's shell (inside the outer metal cover and insulation blanket).

When the temperature of the solar panels is above the tank temperature by at least 10 degrees (on some controllers this is 20 degrees or may be adjustable) it starts the pump. When the tank temperature is near the solar panel temperature (usually within 3 degrees) the pump shuts off.

If the tank sensor is "shorted" or fails, the controller will think the tank temperature is far below the solar panel temperature and turn on the pump, even if it is below zero outside and at night. Use common sense. If you know the tank is not very hot and the sun is bright, the pump should be running. If it is dark outside, the pump should be off. If you "short" the tank sensor terminals with a short piece of wire, the pump should run. If not, there is a good chance the pump has failed.

Remember, the controller is compairing two separate temperature sensors before deciding to turn the pump on or off, so this should make it easy to verify proper operation.

Good luck,

Jeff Yago



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