Southern Alaska winter time sun hours for a off grid solar and wind system

henry1 · April 2011

I was offered a job there in Juneau area and i was looking to retire there in the future ..It going to be about 45 miles south of Juneau on a small 1/2 half sized lot .. The land has great view of the sun in the southern sky as it pass overhead along with the area is also great for a small wind turbine for there is a breeze comeing off the ocean dureing the day and it strong enough to run a small turbine system as the day i wa there the wind was going like crazy at a good clip ..The place is going to be a weekend getway starting out at first then after retirement it going to be a full time place there

I have done the home work for the Amp hours that i'm going to use in the cabin with all the appliance's i have chose for the place ..Everything i chose for the place is 12.volt or enegry star rated type appliances to squeeze out the lowest wattage i can out of the 120.volt items i have bought for use at the place ..

My biggest problem is trying to figure out the winter months from Oct To Feb time frame and how many actul hours of sun i will get dureing the days along with the small wind turbine system for i need to make the solar panel to get the max amount of sun light to make power for the place..

My system design calls for the panels -x-six Kyocea KD135GX 12.volt panel's on a pole system with a Air X 200.watt air tubine on a 15.ft tall pole system to recharge the battery bank and wire as they are need for use to charge the bank unit as it need

As part of the planed system is to use a Outback VFX3648 Flexpowe all in one system for the inverter along with dc and ac fuse boxs and multi other units put into one unit for makeing it easy to wire up and mount on the mud room wall where the battie rack is going to be at

The batties are Sun Xtended 12,volt PVX 2580L AGM sealed Batties -each batties has a 255 amp hours over a 20 hour time frame ..

The system i have design for the cabin is design to use a two battery bank set up of 10-.battery's each with the system working as follows

1-bank 1-is online running the cabin and provideing all the power as it need to all the units that are on and running at the time from the tv to laptop computer to the rv water pump for the sinks and shower ..

2-bank-2-is off line and beening charged with the solar and wind combo system and the reason why for a week long charge time i was told this alot better for the battery bank to allow it to be charged up over time than to try and force the charge on the bank like a gen set does when it chargeing the system ..

The bank's are design to last seven day with a five day back up in the bank system for a total of 12 days if the sun is not shineing and the other bank is not ready to go right on the seven day mark for switch over to the freshly charged bank ..

The heavyest loads on the system are done on diff days to allow the bank not to over taxed the battery bank it self and make them last for a long time intill ..

The laundry is handle on a Sat morning and all the bakeing for the week is done on a Wed dureing the week and the rest of the week is the basic everyday items like dvd player and tv or laptop computer with sat internet set up for use ..The lights are all led low power type and the water pump for the washer unit and shower system is rv high pressure 12.volt unit to handle those chores for pumping of the water from the water stowage tank into the sinks and shower and washer unit

So what do you think of the off grid system i have design for a small off grid cabin there for future use there in Alaska

Cariboocoot · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

Welcome to the forum.

You're going to want to run the PV WATTS program for your locale. http://www.nrel.gov/rredc/pvwatts/
It will tell you what you can expect for solar harvest in your area. Speaking as a fellow "North of 50" resident, I can tell you it's not good. Along about December we run out of sun. Your proposed 810 Watts of panel will disappoint. On a 48 Volt system with 255 Amp hours you're going to want at least double that in panel. I have 700 Watts on a 24 Volt system with about the same battery capacity and it is inadequate without careful load shifting. It is not used in Winter. And a back-up generator power is a must.

As for your indications of having multiple battery banks and many days' reserve ... forget it. As mentioned above those panels are barely adequate for recharging one bank of 255 @ 57 Volts. A generator is a far cheaper alternative to massive battery banks and huge arrays. If you can set up your system with one bank that gets discharged only 25% for one day, then you have 2 days capacity right there (maximum discharge of 50%). On the third day, start the generator.

Not sure why you picked AGM's either. Expensive on a per Amp hour basis, and possibly not the best investment for a first battery set. It's very easy to under/over charge batteries and AGM's aren't forgiving of that (as opposed to FLA's). Better to start with some cheap golf cart type batteries, then change for the others after you've got everything "dialed in". Nothing like being able to take an SG reading to know what the bank is doing. Battery monitors are good too, and a must for AGM's.

henry1 · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

I have been looking at the numbers the one company give me and i been trying to figure them out by there system and i can get the small figures with my math it seams ..

The biggest with a fuel driven system it the transporting of the fuel to the location it done by a atv type vehicle or a person back and it still a major chore to get the fuel back to the place where the clearing is for cabin and the solar and wind set up for the place

The place is located about 20 min walk from the one major road in the area and it not bad with a atv or a 4 wheel drive truck but dureing the fall or when it raining it a little hard to get back into the place

niel · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

funny thing about the sun is that when you want and need it the most is when it's there the least, aka winter. wind may help, but not with an air x. wind turbines are more mechanical and subject to wear and breakdown and you know when that will happen. see the thread on swwp created by truth squad.

it isn't totally bleak though as when the sun shines on pvs with snow on the ground it gets a bit of a boost because of reflection. also, there is talk of some turbines doing ok and are using the new classic controller with very good success. keyturbocars is very into this aspect and it is still ongoing in tweaking it. he has shown nearly 4kw on a 2kw turbine.

if you are worried of gassing of fla types indoors as your reason for going agm i can then understand starting off with the agms. do be careful that they aren't overcharged as they are a more expensive battery, but they are also more efficient than fla types too. i totally agree with the generator and just have one large battery bank that is good for a few days, but the final decision will be yours on the battery bank for a genny sized right can supplement the loads to your place while also giving a charge to the batteries if you have the extended gloom of winter over your head. keep reading up on things so you may know if you'd want to make any changes in your plans before you start into it.

henry1 · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

One of the main reason i chose the AGM was the fact that i was going to be doing a long slow charge to allow the battery bank to be charged over a longer time frame and not worry about the units heating up dureing the chargeing time frame with each day it recharge a little intill the battery bank is bought back to full charge ..

The battery banks is in a off set room like a mud room set up where it been vented and fans system to alllow anything that does happen to escape from the area and not become a problem

the total daily watt's without the cooking and laundry loads on the unit is less than 300.watts a day with everything beening used that day ..

The Air X Marine design was the idea unit in my thinking because of the design for use on sailboats in the open ocean air and the land is located about 4 miles for the ocean and have the problems with the salt and other elaments that are in air and areas because of the ocean system that is around the areas ..I figure it would be beter to go with a smaller set up like a Air X marine unit that i can take down and do basic PMS on it to keep it running and putting it up and down

westbranch · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

Henry, did I read your post correctly about the number of batteries you will have, 10 x 12 volt batteries in each string...

If this is correct you will have them wired up in a 120V DC configuration and you are planning on using 48 volt equipment?

You mention that you will have 2 strings, that makes 20 batteries that could make 5 strings at 48 volts, this is not an easy task to get all the banks evenly balanced.

please confirm the battery bank setup you plan on using.

Eric

BB. · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

There can be some very difficult issues with large battery banks and "slow charging"...

Basically, the problem is that Lead Acid Batteries have a few operating points which they do not like:

Cycling below 20% state of charge--Can permanently damage one or more cells/batteries. (weak cell gets "reverse charged" by neighbors and is pretty much killed--a more difficult problem "to see" on 48 volt battery banks where 2-4 volt bank voltage drop does not shutdown equipment as it would on a 12 volt bank).
Keeping a Battery Bank below 75% state of charge for days/weeks. The lead sulfate begins to crystallize and removes the compound from any more chemical relivance in the battery's storage of energy (i.e., quickly reduces Amp*Hour capacity. Most systems would need new batteries when ~20-50% of capacity is lost (due to sulphation and other causes).
Another "softer" rule of them is try not to cycle below 50% state of charge... The more often you do that, the shorter the cycle life of the battery... The reason is it is a "soft rule of thumb", from my point of view, is that if you buy 2x the amount of batteries for to avoid the 50% discharge, the bank will only last ~2.2x as long--So $$$/Usefulness becomes more of a wash (bank lasts 2x longer buy you have to by 2x the number of batteries).

So, we tend to recommend that people do not go below 5% rate of charge with their solar array (i.e., 100 AH batter should have a minimum of 5% charging current from array or AC battery charger)...

Yes, there are good reasons to not follow the above rules (at times), but try to stay within the rules.

Another driver for costs is fuel usage. Try to have your genset operating at a minimum of 50% of rated load... That will give you a reasonable kWH/Gallon of fuel (just like MPG).

For example, a small bank with a small genset (say a Honda eu1000 or eu2000 family) driving a smaller AC charger will use probably just as much fuel as a 4x larger battery bank, with 4x larger genset, and 4x larger AC battery charger.

And if the loads are not kept high on larger genset (sneak down to 20% or less), you may use 2-3x as much fuel trying to keep everything charged during the winter (as well as much more upfront costs for batteries, genset, charger, etc.).

Fuel choice will affect storage, generator costs, etc... Diesel, propane, gasoline. Diesels tend to be larger (5kW and up) and really need the 50-60% minimum loads for proper operation (but are more fuel efficient on a kWH/gallons basis)...

5kW diesel, 2.5 kW minimum load. Honda eu2000i, 400 watt minimum relatiely fuel efficient load (and darn quiet too).

Getting a small 1,600 watt generator plus a cheap 3.5-5kW for the occasional bigger loads (and emergency backup) works well too.

And there are some very nice Propane Conversions for the smaller gasoline gensets (propane is the least energy per gallon of fuel, and obviously hauling pressure tanks around.

Start playing with some real numbers (Watt*Hours per day Summer vs WH per day Winter, etc.). and size out the "large" and small system and comparing their costs and usefulness for you.

-Bill

henry1 · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

westbranch wrote: »

Henry, did I read your post correctly about the number of batteries you will have, 10 x 12 volt batteries in each string...

If this is correct you will have them wired up in a 120V DC configuration and you are planning on using 48 volt equipment?

You mention that you will have 2 strings, that makes 20 batteries that could make 5 strings at 48 volts, this is not an easy task to get all the banks evenly balanced.

please confirm the battery bank setup you plan on using.

Eric

The string is design with each bank beening 10 batties in the string wired for 12.volt use not 48 volts or 120.volt and it was design from the get go as a 12,volt system

The design to have one bank on line and one bank off line beening charged at the time in a week long chargeing of the battery bank and that way the system is not alot of stress on the system in the long run .

The 120 volt power needs runs through a inverter to meet that need

henry1 · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

I just finish reading the whole thread of Air X breeze wind turbine as a part of the add on to the system .. The scareing part of some of the post is that some of the comments about the service and the product going down hill fast and it not going to get better so i been looking at diff places for another turbine

westbranch · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

Henry the VFX 3648 model inverter uses 48 volt DC in, 3600 VA 120V AC out, that is why I said you have to wire the batteries differently.

See here:

http://www.outbackpower.com/products/sinewave_inverter/off_grid/

If you want to go 12v you will need a different inverter possibly an FX2012 model, also shown in the above link

hope this helps

Eric

henry1 · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

Thanks for the feed back on the system and it can come in a 12.volt set all you have to do is have the dealer order it that way and they will make it up that way ..so i'm going to stick with the whole set but with larger inverter also and few extras ..

westbranch · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

Henry, I suggest that you post a list of all your power requirements, for each item you want to use, so we can get a good understanding of what you need, then we can help you plan for a good system that will fit your needs.:D

Eric

henry1 · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

i will do it here in a bit and thanks you for the info about the system ..

henry1 · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

Here is my list of appliances i will be putting into the cabin

120.volt items

-1-stand up Fulcum reading lamps-x-9.o amps per hour

2-fulcum desk lamp-x-9.o amps per hour

3-mircowave oven-x-100 amp per hour

4-force 10-2-burner compact sailboat stove with oven-x-120 amps per hour

5-rv combo washer and dryer-55 amps per hour

6-small toaster-x-91.6 amps per hour

7-cable internet modem -x-.0.8.amps per hour

8-tankless hot water heater for shower and single kitchen sink-x-12.5.amps per hour

9-philips electric shaver recharge.-x-1.8.amps per hour

10-radio with scanner and other fuctions-x-3.6 amps per hour

12.volt items

1-mac book laptop -x-17 inchs screen-x-40.amps per hour

2-h.p.protable printer -x-6.5 amps per hour

3-ipad rechargeing -x-2.o amps per hour

4-iphone rechargeing-x-2.o.amps per hour

5-lights for the place in the diff areas in the cabin from the kitcen to the bed area to the bed light -x-10.amps per hour

6-security alarm system with motion system from a reworked 12.volt car alarm system -x-0.5.amps per hour

7-rv style high pressure water pump to pump the water from the 250 gallon stowage tank to the kitchen sink or shower or washing machine as need -x-8.5.amps per hour

8-compact 12.volt fridge -x-2.8.amps per hour

9-22.inch color flat screen tv-x-9.7 amps per hour

10-dvd player-x-3.2.amps per hour

11-air blower for the heater system-x-5.amps per hour ..

all lightins that is 12.volt is going to be led type and the 120 volt items are the most enegry rated items i can get for the low wattage use dureing there operation ..

The biggest three power hogs in the system are the force 10 stove with the mircowave oven and rv washer and dryer unit for the place ..

Because of useing a earth berm style building for the retirement cabin i can not go with the normal propane or lg. type items in the place because of the problems of a leaking gas line inside the house..

icarus · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

Whoa there Trigger!!!

From the sound of it, you are looking at a (comparative) massive load for a battery based system in SE. Unless you are prepared to run the genny a lot, and or build a very expensive system you might wish to re-think your loads.

First thing, when you are figuring your loading, you must include a time component. 120 amps "per hour" is a non figure. 120 amps, running FOR 1 hour would be 120 amp/hours at what ever system voltage, in the case of the the stove 120 vac. 120 ah @ 120 vac would be a whopping 14,400 wh, per hour. I don't think that is what it draws.

Next, for example, the stove. Why would you use an electric stove? A propane or fuel oil stove will be much cheaper to run net/net. A toaster, at say 1500 watts, running 6 minutes per day will burn 150 wh. Making toast with a different device will make your system that much cheaper to build and run.

An electric tankless water heater will also kill your system. By your figuring 12.5amps=1500 watts, and by my guess it will run 2-4 hours a day (6 kwh) to provide enough water for showers and dishes etc. Consider a Propane demand or even a Propane tank type instead.

Personally I would also do a way with the washer and most certainly the dryer, although in SE I understand the desire for a dryer, but consider a gas unit instead.

The hard reality is that PV solar is going to be very expensive given the location and the loads you desire. As a comparison, we live off grid. We consume ~ 5-800 watt/HOURS of power per day, and get that from ~ 400 watts of panels. Your tankless water heater alone will consume roughly 10 times our daily use. Add in the other big draws and you could easily be 30 or 50 times ours. 30 times would be 12,000 watts of panels, and ~ 3500 ah of battery (@ 48 volts) a 23 kw off grid system might cost ~$75,000?

The bottom line is spend every thing you can on conservation. Use alternative fuels for everything that you can. We use electricity for water pumping, lighting, fans, tool charging, radio, computer and modem (no tv) portable tool charging when there is excess sun and a few other things. We do not use it for any heating appliance except a soldering iron, and even then I use the butane one if I can. We have a propane toaster, a stove top coffee maker, gas stove, demand hot water, a gasoline powered washing machine, no dryer, no hair dryer, no micro.

Spend some time and do some real calculations as to your loads, and how long they are going to be on for, so that you can come up with a real load calc. The two rules of solar (really three,) is that people at the same time under estimate their loads, and over estimate the amount of harvest they can actually get. The other is that loads will almost always grow with time.

Finally, a quick equation that might help our thinking. My general rule of thumb for off grid solar is this: Take the name plate rating of the PV, divide that number by 2 to account for all cumulative system loses, then multiply that number by four. The four represents the average hours of good sun one might reasonably expect on a daily, on going basis over the course of the year. In your case, I suspect that 4 number is going to be way too big in the winter, and is more likely to approach 0 in SE. Winter might be more,, try the PV watts calc mentioned before.

So once again, for comparison, our 400 watts of PV would look like this, 400/2=200*4=800. Just about exactly what we use.

Good luck and keep in touch,

Tony

Cariboocoot · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

That load list is definitely not compatible with any system under 48 Volts.
Electric on-demand hot water heater is a nightmare. They are a bad idea even with grid power. A tank type with a timer on it would be better; on when the batteries are full and the sun is shining, hope the insulation keeps the heat in overnight.

Your projected loads are way beyond what those panels could handle. Way beyond. This needs a serious re-think.

BB. · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

You mentioned not wanting Propane because of the home construction... Is this up for negotiations? There are flammable gas sensors that are used on boats and other critical locations. Also, for example, boats sometimes use alcohol stoves because they can use water to put out any fuel related fires.

I know some people just don't want natural gas in their home because of some bad experiences before/or happened to relatives.

But running an all electric off-grid home in Alaska, short of a 24x7 genset, seems a bit out of balance with capabilities of solar PV.

There are some things that may be done--using solar thermal for space heating and basic domestic hot water. And there are heat pump hot water heaters that are 2x as efficient as pure electric--but those don't work very well below ~55F or so (use backup resistance heater for hot water).

In general, people should try to aim at 100 kWH per month (~$10-$20 per month electric bill) for an off-grid home. An all electric home can be 1,000+ kWH per month--which may be possible in the desert south west (with lots of sun year round)... Alaska, perhaps in summer with a tracking array you can have a fair amount of power--But probably not enough to a full electric home.

-Bill

henry1 · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

icarus wrote: »

Whoa there Trigger!!!

From the sound of it, you are looking at a (comparative) massive load for a battery based system in SE. Unless you are prepared to run the genny a lot, and or build a very expensive system you might wish to re-think your loads.

First thing, when you are figuring your loading, you must include a time component. 120 amps "per hour" is a non figure. 120 amps, running FOR 1 hour would be 120 amp/hours at what ever system voltage, in the case of the the stove 120 vac. 120 ah @ 120 vac would be a whopping 14,400 wh, per hour. I don't think that is what it draws.

Next, for example, the stove. Why would you use an electric stove? A propane or fuel oil stove will be much cheaper to run net/net. A toaster, at say 1500 watts, running 6 minutes per day will burn 150 wh. Making toast with a different device will make your system that much cheaper to build and run.

An electric tankless water heater will also kill your system. By your figuring 12.5amps=1500 watts, and by my guess it will run 2-4 hours a day (6 kwh) to provide enough water for showers and dishes etc. Consider a Propane demand or even a Propane tank type instead.

Personally I would also do a way with the washer and most certainly the dryer, although in SE I understand the desire for a dryer, but consider a gas unit instead.

The hard reality is that PV solar is going to be very expensive given the location and the loads you desire. As a comparison, we live off grid. We consume ~ 5-800 watt/HOURS of power per day, and get that from ~ 400 watts of panels. Your tankless water heater alone will consume roughly 10 times our daily use. Add in the other big draws and you could easily be 30 or 50 times ours. 30 times would be 12,000 watts of panels, and ~ 3500 ah of battery (@ 48 volts) a 23 kw off grid system might cost ~$75,000?

The bottom line is spend every thing you can on conservation. Use alternative fuels for everything that you can. We use electricity for water pumping, lighting, fans, tool charging, radio, computer and modem (no tv) portable tool charging when there is excess sun and a few other things. We do not use it for any heating appliance except a soldering iron, and even then I use the butane one if I can. We have a propane toaster, a stove top coffee maker, gas stove, demand hot water, a gasoline powered washing machine, no dryer, no hair dryer, no micro.

Spend some time and do some real calculations as to your loads, and how long they are going to be on for, so that you can come up with a real load calc. The two rules of solar (really three,) is that people at the same time under estimate their loads, and over estimate the amount of harvest they can actually get. The other is that loads will almost always grow with time.

Finally, a quick equation that might help our thinking. My general rule of thumb for off grid solar is this: Take the name plate rating of the PV, divide that number by 2 to account for all cumulative system loses, then multiply that number by four. The four represents the average hours of good sun one might reasonably expect on a daily, on going basis over the course of the year. In your case, I suspect that 4 number is going to be way too big in the winter, and is more likely to approach 0 in SE. Winter might be more,, try the PV watts calc mentioned before.

So once again, for comparison, our 400 watts of PV would look like this, 400/2=200*4=800. Just about exactly what we use.

Good luck and keep in touch,

Tony

The hot water heater is only for the shower and kitchen use and not for the washer the washer is cold water use only

The reason why no propane is for a earth berm home or semi underground home and that why i will not use a propane system inside the place

icarus · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

Henry,

Even only using the hot water heater for the shower and the dishes is a huge draw.

As for no propane, in an earth sheltered house: While I applaud the idea of an earth sheltered house, I think that allowances can be made for propane drainage system.

For those that don't know, propane is a liquid, and is heavier than air. In the event of a large leak, liquid propane can (and will) pool in the lowest point in a house. As a result, it is a UBC code requirement that any propane installation have the ability to drain in the event of a leak.

My personal opinion is that if you have a leak that is big enough for propane to pool, you probably have a problem big enough that a drain is not going to solve, but that is another matter.

I have built and installed propane systems with gravity drains in a whole selection of odd building designs (that have passed code enforcement) including covering all the indoor gas piping in DWV pipe that exits to daylight in the event of a leak in the piping.

There are a number of gas detection systems that can be coupled to tank and regulator valves that can stop the flow of gas quickly in the event of a detected leak.
Of course, this is probably a conversation for another thread.

The point however, is that using resistance electric heat provided by solar is terribly inefficient. In the case of hot water, if you have the kind of solar (insolation) to produce PV power, you are nearly orders of magnitude more efficient to heat water directly, for example.

In the real world, I think you have to re-think your choice of not using propane or fuel oil for your heat source appliances like the range, hot water etc.

A quick look at PV watts for SE reveals an potential energy harvest in January of less than 1 kwh per kw of installed PV per day. (averaged over the month) That means, in real terms to run the kind of loads that you are talking about, say 15 kwh/day, you are going to need a minimum system size of ~ 15 kw if you are looking for reasonable service in the winter. 15 kw system might cost ~$8/watt, or ~ $120,000, ~ 1/3 of which is going to be batteries that have to be replaced every 5-10 years.

Tony

henry1 · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

what adding a Victory Gasworks Gasifier unit in the 5.kw range along with a small Honeda EU3000. gas gen set for use with the winter time chargeing system

The Gasifier would be used for major battie charger system in the winter time and the gas gen set up use as a back up system also ..

icarus · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

I am certainly no expert (in fact have no history at all) with wood gas, but I find after doing a bit of reading, that I would be skeptical except for the serious DIYer.

For example, what kind of effort/energy is required to cut/haul/store the wood required for gasification, and is that the best use for that effort/energy?

Tony

pogonip · April 2011

Re: Southern Alaska winter time sun hours for a off grid solar and wind system

I have been to Juneau a number of times and have a number of friends there. It is not uncommon to not see the sun for 2-3 weeks at a time. I would think you need to check out the amount solar available before buying your solar equipment. I don't think it is a very friendly solar area. The area is very lush due to all the rain.

Good Luck

Dan

Southern Alaska winter time sun hours for a off grid solar and wind system

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