Making up our own solar system!

Redford · June 2007

For the past 4 years my wife and I have been building our own house. Right now for power we have 2, group 29 batteries (parallel linked, Sears Marine Diehard type) 3 solar panels that supply 30w each (90w total) and a charge controller that is rated for up to 7 amps. It's not much, but it's all I could afford at the time.

I have a Honda EU3000 series generator which I run for about an hour every morning to make coffee and to power our AC water pump which fills our 1000 gallon reservoir. At the same time I usually bulk charge the batteries at 15amps via an micro-processor controlled automotive charger for an hour in the morning, then the solar power trickle charges during the sun hours.

This has gotten us by for the past 3 or 4 years and it's time to get a system which will offer us a lot more flexibility and power.

I wish to design an array/system which would accomodate a modular pay as I can afford type of system. I'm kind of liking the modular aspect of the Outback systems. So I would probably start by getting new batteries, panels, and an MX-60 controller. I will need to integrate the EU3000 in the system on a switching circuit that would automatically let the generator power the house directly as it also charges the batteries.

One thing we don't really understand is all the numbers!

We wrote down all that we would use for power and decided that our house will have small enough wire runs to keep the system at 12 volts.

For DC Power Requirements we have:

Lights:
6 Alpenglow flourecent fixtures rated at 9 or 13watts (total useage of lights per day is about 9 total hours....4 lights used 2 hrs/day....the other 2 used one hr/day
2 IMTRA marine recessed spots with a 20 watt draw used about an hour per day
Radio:
50 watts 5 hours/day
Satelite radio reciever 10 watts 5 hours/day

TV:
We watch TV on average 1 hour per day (which is over our norm). It's an LCD Tv which is rated at about 75 watts
Satelite Reciever: We were looking into getting a satelite reciever so we can watch the discovery and the history channel. We don't have one yet but I would hope it would draw less than 100 watts/ 1 hour per day.

Water:
SHURflow positive displacement pressure boost pump (we haven't bought this pump yet)
Will draw about 5 amps (12v) I really don't know how much it will run?!?! I suppose it depends on our water useage.

Our refrigeration is all propane.

So here's the system we would *hope* to get when we save up the money.

Panels : 4 Evergreen Solar Panels, model ES-170-RL
Charge Controller: Outback, MX-60
Batteries: (6), AGM, 8D batteries linked in parralel

In time, we would like to obtain a large inverter (4000 watts pure sine wave) to cut down the use of the generator.

We live in NY which during the WORST time of the year has a solar insolation value of 4.174 kWh/sq-m/day.
But with the generator, I don't mind running it to charge the battery bank.

At optimum, the panels will supply 26.8 amps which one MX-60 would handle fine.

I was just wondering if we are on the right track to be able to expand our energy production in the future and also incorporate our present power needs and more.

If there is anything that you could suggest we could really use the help!

---I thank you in advance

***EDIT*** the solar value for my area is 4.174 so it's a little better than I initially thought!

niel · June 2007

Re: Making up our own solar system!

you'll have to add up the wattage you'll need for the day to see if the system you chose is suitable, but do you really need 4kw of inverter power? most of everything you said is dc and i don't think your ac needs from the inverter will need to be this high. the loads on the generator may be that high because you are running all loads and charging batteries.
be aware that when using a downconverting mppt controller outputting 12v from 24v that the current is not delivered at the same rate as what it is at 24v. it is automatically doubled and is also typically 10% more than that for the mppt boost when applicable. that means that the 26.88a 24v is now 56.76a at 12v plus any boost from mppt. this will deliver twice the current at 12v as you had originally figured. the mx60 will handle it though.
as to the batteries, 6 8ds paralleled will be in the area of 6x250ah=1500ah at 12v total capacity. inputting the 56.76a to this is a 3.784% charge rate. this is a bit on the low side, but is workable. much less and the batteries may never reach their full charge so if it your determine that you can eliminate one of the batteries, this would be a plus in the % charge rate or you'd need to get more pvs to up the %, which at 12v can complicate things some as you're over the limit area for it outputting at its modified rate of 70amps. if the pv charging amps would've been as you thought at 26.8a the batteries would probably have not reached their full charge even after many days of solar charging. yes, you can still use the genny to help charging.
not sure what this is: "The solar rating of your area is Good for adopting a solar system. This is based upon a solar rating of 4.174 kWh/sq-m/day. Now, we'll do some estimating for you:" the sun does not have that much intensity anywhere on the earth.

crewzer · June 2007

Re: Making up our own solar system!

niel,

"...4.174 kWh/sq-m/day...the sun does not have that much intensity anywhere on the earth."

Sure it does -- even near Pittsburgh!

We just don't use that jargon much around here.

"Full" insolation at sea-level is 1 kW/m2. With the equivalent of 4.174 hours/day of "full" Sun, that would be 4.174 kWh/m2/day. PV module efficinecy is another thing, so, assuming ~12% efficiency, the STC equivalent output would be ~500 Wh/m2/day

HTH,
Jim / crewzer

Redford · June 2007

Re: Making up our own solar system!

We need to do the wattage requirement worksheet again!

As for the 4k inverter our dream is to *someday* have a toploading energy star washing machine before we have kids! That makes life a lot easier. I was hoping to run it off a large inverter and am not sure of the power requirements for each brand/model.
So I kinda figured bigger was better.....

I didn't realize that the amperage would double as well as the current! But it makes sense now that I think about it.
This is exactly what I needed to know!

As far as the batteries vs. panels....we should go with more PV....but it all depends on how the useage worksheet comes out I suppose. I just want to make a system that will allow our family to grow without too much power limitations.

What % charge should I shoot for when designing a system?

(oh and the last part about the "solar rating of my area" I just copied that down there so I could remember the solar insolation number)

Thanks for your help!

crewzer · June 2007

Re: Making up our own solar system!

I think I came up with an average daily energy requirement of ~700 Wh. Assuming overall system efficiency of 67% and a December average of 2.1 hours/day of “full” Sun, you’ll need a PV array rated at (700 Wh/day / 67%) / 2.1 hours/day = ~500 W. If the 700 Wh/day is correct, you’ll have plenty of energy generation capability in the summer (5 – 6 hrs/day of “full” Sun).

Assuming 700 Wh/day and 90% inverter efficiency, the energy requirement from the battery bank will be ~780 Wh/day. Allowing for three days of autonomy (no Sun) and limiting the battery discharge to 50%, you’ll need a battery bank rated at 780 Wh/day x 3 days / 50% = ~4,700 Wh. For a 12 V system, that’s just 390 Ah. Allowing for cold winter temps, a pair of 8D AGM batteries (~500 Ah total) would work, and they’d be a good match for the 500 W PV array.

An Exeltech XP 600 W inverter would be fine for these needs, and the Honda generator has a “12 V” charger”.

I suspect there’s something amiss with your energy estimates and/or my math. I recommend you review your loads and run the calculation. For each load, it’s just Watts/device x time x number of devices. For example, for four each 13 W lamps for 2 hours/day, that would be 13 W/lamp x 2 hrs/day x 4 lamps = 104 Wh/day.

HTH,
Jim / crewzer

Added on edit: OutBack's biggest 12 V inverter/charger is the VFX2812 (2,800 W). It's not 4,000 W, but it's plenty capable. My OutBack inverter is the 2524, and it can handle our front-loader washer, fridge, and entertainment system -- simultaneously -- with ease. I also like niel's idea of a 24 V system... lower DC currents, and higher efficiency through the MX and the FX. The generator couldn't charge the 24 V battery bank directly, but the OutBack inverters include a high-quality built-in battery charger.

niel · June 2007

Re: Making up our own solar system!

crewzer wrote:

niel,

"...4.174 kWh/sq-m/day...the sun does not have that much intensity anywhere on the earth."

Sure it does -- even near Pittsburgh! We just don't use that jargon much around here.

"Full" insolation at sea-level is 1 kW/m2. With the equivalent of 4.174 hours/day of "full" Sun, that would be 4.174 kWh/m2/day. PV module efficinecy is another thing, so, assuming ~12% efficiency, the STC equivalent output would be ~500 Wh/m2/day

HTH,
Jim / crewzer

ok, hitting my forehead, i overlooked the per day thing.

"I didn't realize that the amperage would double as well as the current!"
the amperage is current.

"What % charge should I shoot for when designing a system?"
there isn't exacting figures, but we do agree that as low as a 3% without loads, with 5%-10% being best and some batteries can take more depending on the battery and if there is a load on it at the time. (we have had many posts on this subject and you may wish to look for some of them.) that last part with the battery and load might confuse you, but if you have say for an example a standard 100ah battery and have a 10amp load on it while feeding 13amps from pvs this works out to 13-10=3amps net charge and 3/100=3% or just in there, but acceptable. if the load is 5amps and you're feeding 13amps this is a net charge rate of 8amps and is 8% on a 100ah battery. this part you have to watch for as that 13amps without a load is a 13% charge rate on a 100ah battery. most batteries can handle a 13% rate of charge, but you'd better be certain from the manufacturer that the highest rate would be tolerable to their battery. most of us don't worry too much about this as most can't afford the pvs to produce that higher rate of charge in moderate to larger systems. :-o

as explained before, you could feed the 3% rate without a load too as this results in the same 3ah charge for the battery and is acceptable. do understand though that at a 3% rate of charge it will take 100%/3%=about 34 hours of full sun to fully charge and more with losses and other factors. a higher rate of charge yields a faster charge, but in the final stages it does cut back on the current via the controller's regulation so we are talking about the bulk charge stage here which accounts for about 80-90% of the battery capacity. i encourage you to readup some on this.
as i said before, the way it worked for the pv's output at 12v and the batteries you planned on, its charge rate is within acceptance without a load on it. do note that there is a limit to 12v operation on the mx60 as i tried to explain before. there is an approved modification for the controller to be rated at 70amps output and that the input for 12v would be 70/1.25=56amps on the input so you are maxed out with the pvs you have chosen and using a 12v output from the mx60 controller. another controller would be needed in addition to this one and possibly a hub and mate for more pvs. now if your system was working at 24v instead of 12v the power capability would double on the mx60 and it would be expandable out to another 4 of those pvs, but you need to run 12v items so unless you're willing to make a changeover with the items running on dc to 24v(or use a converter sacrificing efficiency) you'd need another controller(mx60) to handle any more pvs. getting more pvs and another mx60 and associated items for it would be a future expansion you could do though and the system is workable as it is now, but with a slower rate of charge from the pvs.

SolarJohn · June 2007

Re: Making up our own solar system!

Crewzer said:

An Exeltech XP 600 W inverter would be fine for these needs, and the Honda generator has a “12 V” charger”.

I would opt for the 1100 watt Exeltech inverter instead of the 600 watt Exeltech. For about the same price you’ll get nearly twice the power. You'll be able to run things like a microwave oven, toaster, etc., that the 600 watt unit can't handle. Still, you might have problems with appliances, like a washer and dryer. A Xantrex inverter will do the job, but the cost is three to four times greater than the Exeltech 1100.

Based on your requirements, I'd opt for the Exeltech 1100, and use the rest of my budget for solar panels.

John

Redford · June 2007

Re: Making up our own solar system!

Thanks so much for all your input! I'm starting to get a good grasp on this now.

This morning I re-did my power usage requirements again.....and this time I added the AC loads that I would like to accomodate in the future (ie. vacuum/clothes washer/sat. tv/ etc.)

The estimates are for the MOST that I could ever see us using the electrical items, and it came out to 1675 W/Hrs/Day which is more than double of what we use now.

Appliance DC or AC watts Hours used/day Device #'s Watt Hours/day
Alpenglow lights (6) 10 DC 3 6 180
IMTRA lights (3) 20 DC 3 3 180
IMTRA LED lights 50 DC 2 1 100
Radio 50 AC 5 1 250
Satelite radio receiver 10 DC 5 1 50
Television* 80 AC 2 1 160
Satelite TV receiver 25 AC 2 1 50
SHURflow pump 60 DC 4 1 240
Vacuum Cleaner* 500 AC 0.5 1 250
DVD Player 30 AC 0.5 1 15
Washing Machine* 400 AC 0.5 1 200

TOTAl = 1675 W/Hrs/Day

* for a couple items I had to multiply the AC amps x voltage to get, what would technically be, the volt amperes and I'm not sure if it can be used as the calculation for DC watts.

As far as the inverter....I'm glad to know that I can run a washing machine off a FX2524 Outback inverter! That is a great inverter and the largest AC load on my list will probably be the vacuum (which is used sparingly)

I like the idea of converting the system to a 24v system for better efficiency and expansion. However I don't like the idea of replacing all my 12v lights, radios and such. In your opinion would it be better in the long run to install a 24v system and put 24vDC > 12vDC voltage reducers on each 12v circuit?

Or

Install a 12v system, then down the road accomodate for expansion with another mx-60, mate, hub, panels.....?

mike95490 · June 2007

Re: Making up our own solar system!

Redford wrote:

I like the idea of converting the system to a 24v system for better efficiency and expansion. However I don't like the idea of replacing all my 12v lights, radios and such. In your opinion would it be better in the long run to install a 24v system and put 24vDC > 12vDC voltage reducers on each 12v circuit?

I'd go with 24V, and then for each circuit, get a DC-DC converter. They run 80-90% efficient, and are better than linear regulators that are 50% loss. (LM7812 3 term regulator)

niel · June 2007

Re: Making up our own solar system!

"I like the idea of converting the system to a 24v system for better efficiency and expansion. However I don't like the idea of replacing all my 12v lights, radios and such. In your opinion would it be better in the long run to install a 24v system and put 24vDC > 12vDC voltage reducers on each 12v circuit?

Or

Install a 12v system, then down the road accomodate for expansion with another mx-60, mate, hub, panels.....?"

that's a tough one to call, but based on your future needs for power and seeing more efficiency at 24v i personnally would make the plans for a 24v system. in the meantime, the many 12v loads could be run off of a converter until they are slowly phased out for other items to be run on the other system be it either 24v or the inverter. small loads running on a large inverter all of the time isn't good either as this keeps the inverter running at a very low efficiency. when dc isn't an option and given a choice between running small items from the large inverter or a converter is a tough decision to make as neither way will be efficient so it must be investigated as to the lesser of the 2 evils or it may just come down to what is easier and cheaper. this will be your decision though as i can't say what you'd want or prefer to do.
the more you know the more perplexing it can be as you realize more options and possibilities. some may even suggest a smaller inverter to run those other items, but if on wall worts you might have to have a smallscale sinewave inverter for them(some wall worts blow out on modsinewave) and they can be very expensive per watt.
now there is one more option and that is to run 2 seperate pv systems. one for 12vdc and one for 24vdc to be inverted to ac. many might say that is a waste because when you need more 12vdc power it's not available from the other system using the 24vdc to be used for 120vac and it is true, but running a charger off of the 24v system from the 120vac inverter isn't anymore inefficient that many other methods and it wouldn't be for too long. in your case turn on the genny and charge it up some if in the bulk stage of charging. if it's in other stages of charging it will have its charge regulated back so it becomes a waste of the genny power at that point. now you can run another item from the genny at the same time(like washing machine on one outlet and the charger on the other splitting the 240vac from the genny?) making the use of the genny more efficient too. when the 2 seperate pv systems are sized right this would probably yield the highest efficiency. see what i mean about more knowledge/choices and i'm sure others could pop a few more ideas out at you? :roll:

Redford · June 2007

Re: Making up our own solar system!

in your case turn on the genny and charge it up some if in the bulk stage of charging. if it's in other stages of charging it will have its charge regulated back so it becomes a waste of the genny power at that point. now you can run another item from the genny at the same time(like washing machine on one outlet and the charger on the other splitting the 240vac from the genny?) making the use of the genny more efficient too.

That's what we do right now via the automotive charger I suppose. As of now, I really don't mind using the genny for higher Ac loads like my well pump and stuff. I think I'll go with a 24v system with a FX2524 inverter and a dc/dc converter to run my lights. Then, as you say, phase them out over time to all 24 volts.

as per the Dc to Dc converter Vanner's model # 90-20A, INPUT: 22-35 Vdc , OUTPUT: 12.8 Vdc @ output current of 0-20 amps looks like it might do the trick for some of my smaller Dc loads like lights and pump.

crewzer · June 2007

Re: Making up our own solar system!

Redford,

First, good for you for asking about VA vs. Watts. I’ll save you a long dissertation, but AC Volt•Amps are almost always higher that Watts, unless the power factor is 1. So, if you convert VA to an equivalent number of Watts, you’re usually covered.

Second, please let me ask that we all stop using the expression “Watts/hour” (“Watts per hour”), or any of its derivatives, contractions, or abbreviations. There’s no such thing as a “Watt/hour”. Electrical energy can be expressed as Watt•hours (Wh), or power x time, and power is Watts, or the rate at which energy is used. For example, 10 W x 2 hours = 20 Wh, and 50 Wh / 2 hrs = 25 W.

Thanks!

Now, back to the original issue.

Leaving out the “future” vacuum and washing machine, and allowing for 20 Wh loss in the inverter to power the TV, I came up with an initial energy requirement of 1,245 Wh/day. Since the inverter energy loss is already included, overall system operating efficiency will be ~74%, so the gross energy production requirement will be ~1,682 Wh/day. Going back to the 2.1 hours/day of insolation, you’ll need an array rated at ~800W STC.

How convenient! This is the ~maximum array size recommended by OutBack when using their MX60 controller in a “12 V” battery system.

1,245 Wh/day x 6 days = a 12 V battery bank rated at ~622 Ah. Allowing for cold temperatures, something in the 800 Ah range would work, and that’s a good size match for the 800 W array.

How convenient! 4 each size 4D AGM batteries wired in parallel would be 12 V x ~800 Ah.

So, one way (there are plenty of others) to meet your need would be with an 800 W STC array, an MX60 charge controller, four each size 4D batteries, and a 250 W inverter to power the 80 W TV (inverters are typically most efficient @ ~ 1/3 power).

Should you decide to increase your loads at some later date, you could convert to a “24 V” system by rewiring the array to a higher voltage, increasing the array to up to 1,600 W, changing the MX60 setting from 12 V to 24 V, reconfiguring the battery bank from 12 V to 24 V, and adding a nice big 24 V inverter/charger. You’d also need a 24 V to 12 V DC-DC converter.

Just one way to do it…

HTH,
Jim / crewzer

Redford · June 2007

Re: Making up our own solar system!

That sounds good, things are coming together. The only question I would have is with an 800 W array and 4 AGM batteries @ 800 Ah what would be the percent charge?

I'll try to figure it out with what I have learned from this site.
Without a load on the system the charge rate would be:
(assuming the ES-190's put out 7 Amps X 4 panels in ideal conditions....25 will do for calculation)

25 amps (incoming from array) X 800 Ah (battery bank) would be a 3.12% charge rate.

Now the same system with a 10amp load on it, with 25amps coming in from the PV array.

10amp load - 25 amps incoming is a net charge of 15 amps. 15amps/800 Ah battery bank is only 1.87% charge rate.

I'm not sure if that's good or not?!?!!

To acheive 800 W STC from the array, using Evergreen products I would need:

the ES-170's would need 4.7 panels
the ES-180's would need 4.4 panels
the ES-190's would need 4.2 panels

How would one determine the number of panels? If I were to guess I would wager to always round up and increase the angle to the horizon so in summer they don't get full sun, but in winter they get full sun. Am I kind of on the right track?

crewzer · June 2007

Re: Making up our own solar system!

Assuming 80% operational system efficiency in the summer (hot temps = lower PV voltage), you'd see 800 W x 80% / 14.2 V = 45 A, or 5.6% charge current. In the winter, sustained mid-day charge current would probably be ~50 A. On a very cold (~14 F), bright, and breezy winter day, you could see periods of 60 A, and, if there's also snow or ice, you could see upwards of 70 A!

The 5% charge current strategy is one that I like and endorse. But, it's a design target, not an actual operational target. For example, the batteries will begin to charge in the morning even when the charge current is way below 5% of battery capacity, and it does allow for some mid-day loads. Also, you'll not see 45 A to 50 A very often except for bright and clear days

The 5% rule is also something a math shortcut for a well balanced system design. For example, if your average daily energy requirement is 1/6 of your battery bank's capacity (~17%), you just need ~4 hours of "full" Sun -- or 4 x 5% = 20% -- on a average day to meet your energy needs and recharge your batteries. So, if you design for 5% or better, the batteries will still charge under a range of operating conditions and some loads.

On a related note, an effective charging strategy is to minimize daytime loads loads while the charger is in bulk stage, and then apply loads when the charger is in absorb- and/or float modes.

Four ES-190's would get to 760 W STC. You could also consider four GE-200's, or four Kyocera KC-200's, either wired as a 1 X 4 array (~26.3 Vmp x ~30.44 A Imp) for a 12 V system, or a 2 x 2 array (~52.6 Vmp x ~15.22 A Imp) for either 24 V or 12 V systems. The MX60 will automatically down-convert to the selected nominal battery voltage.

See: http://store.solar-electric.com/hiposopa.html

The 2.1 hours insolation figure I used is for a south facing array tilted up at latitude + 15 degrees in Syracuse, NY This angle would help with winter energy production and with snow shedding. It's a bit steep for optimal summer energy production, but it would still work... just more hours at lower charge current. Or, you cold go for two tilt settings: one for winter (local latitude + ~15 degrees) and one for summer (latitude - ~15 degrees).

You're getting it! 8-)

HTH,
Jim / crewzer

westbranch · June 2007

Re: Making up our own solar system!

Jim, can you please explain the determination of + and - 15* for winter and summer angle setting.
thanks
Eric

crewzer · June 2007

Re: Making up our own solar system!

Eric,

Here’s (what's for me

) a short answer to your question.

The optimal alignment for PV modules is perpendicular -- in both azimuth and elevation -- to the Sun’s rays of light. For a south-facing array, the fixed azimuth is optimal only at ~solar noon, and, due to the Earth's axial tilt angle of ~23.5 degrees, an array tilt angle equal to local latitude is optimal only on the dates of the Spring and Fall equinoxes (nominally March 21 and September 21).

On all other days of the year, the Sun's elevation angle is either too high or too low for a fixed tilt array, resulting in ever decreasing instantaneous power output as the Sun approaches the Summer and Winter solstices. The power reduction is proportional to the cosine of the angle error. For example, for a south-facing PV array tilted up at latitude, the angle error is ~23.5 degrees on ~June 21. The cosine of 23.5 degrees is 0.917, so, everything else being equal, the array’s power output would be ~91.7% of that compared to the same array tilted up at latitude + 23.5 degrees.

Making small tilt adjustments every couple of days to follow the Sun would help optimize power production. However, manual adjustments are tedious at best, and a mechanical tracker adds complexity, cost, and maintenance.

Starting with a winter correction, adding ~15 degrees to the tilt angle is a good compromise setting. The maximum cosine error is 0.966, the cosine of 15 degrees, from ~September 21 to ~ March 21 (in the northern hemisphere). On ~December 21, the angle error is only ~8.5 degrees, so the cosine error is only 0.989, which is helpful during winter days of limited “hours” of insolation.

However, a lat + 15 degree tilt increases the summer error to as high as 38.5 degrees, with a corresponding cosine error of 0.783. The logical solution is to cancel the winter tilt offset. Since the array is going to be adjusted anyway, it makes sense to employ a useful summer setting rather than just return to tilt = latitude. Once again, a 15 degree offset makes sense as a compromise setting, so the typical summer setting is latitude – 15 degrees.

The +/- 15 degree approach is not optimal for all locations. I think that slightly different angles work a bit better for latitudes greater the +/- ~50 degrees, so you might want to research that issue.

You can see the effect of these adjustments by looking at the data from a solar insolation record. Since you appear to be in Canada, I’ve selected Kalispell, Montana as an example.

HTH,
Jim / crewzer

westbranch · June 2007

Re: Making up our own solar system!

Thanks Jim, got it after some mental gymnastics.

Had to ' get my mind around it...' but first I had to reverse my angle..in my mind,... had it backwards as my panel is hinged from the top not the bottom...duhhh...

I have used a much simpler system for adjustment, a carpenters square and the shadow cast by the sun mid day. I start changing from vertical around Easter when we first get out and up to the max angle near summer solstice. My (manual)adjuster moves in about 10* increments and I start at ~ 30* first up to ~50* at solstice. then back down to Vertical around Remembrance day (Nov 11)

I use vertical in winter to protect against snow buildup and to gain solar bounce from the snow.

Thanks again
Eric

crewzer · July 2007

Re: Making up our own solar system!

Eric,

"...a carpenters square and the shadow cast by the sun mid day."

Yep, a gnomon. I gather the vertical winter alignment is popular in "extreme" latitudes (and/or some high altitudes) to help with snow shedding and reflection harvesting. Sounds like your method works!

Regards,
Jim / crewzer

westbranch · July 2007

Re: Making up our own solar system!

Ahem, ahem ahem....

Jim, we are NOT in an 'extreme ' latitude here at 51* 47'... :-o
Why is it that so many in the lower 48 think that there is nothing but ice and snow past the 49 th parallel??? :? :?

Geographically we are just inland of the north end of Vancouver Island and at least 300 mile S of the bottom of the Alaska Panhandle and about 200 miles north of the Canadian border ... as the crow flies... which puts us about 1/3 of the way up the province.

Cant break 'gnomon', even asked SWMBO and no luck.. :-D

Eric

crewzer · July 2007

Re: Making up our own solar system!

Eric,

You’re right: The term “extreme” is probably a bit extreme. I’m open to suggestions for more appropriate adjective.

However, to be fair, my comment was meant to address harsh weather conditions and unique environmental conditions such as those often encountered in much of Canada, and even some states in the lower 48, as well as in high altitude locations, with respect to PV system design. My original comment did include a reference to high altitude.

I’ve traveled a fair amount across the northern Hemisphere in North America, Europe, and Asia, and I even went to school for a while in Chicago. I know that Canada in not nothing but snow and ice, and your beautiful avatar is testimony to that fact. But, higher latitudes and altitudes generally do experience long periods of cold, snow, and ice during the winter season, and so we must include those factors in our design considerations. We also consider those factors for systems installed in some of the lower 48 states due to latitude (i.e., Maine) and/or altitude (i.e., Colorado).

And, just to keep things balanced, we also have to factor in extreme hot weather when designing for locations such as the desert southwest U.S. Battery life is shortened by very hot temperatures, which also reduce PV power output.

So, I suppose that I’m trying to say that I meant well, but that doesn’t mean that I did well. I’m still trying to figure out how to say something without offending anybody on the planet.

Here’s a link to some gnomon info: http://www.du.edu/~jcalvert/astro/gnomon.htm

Regards,
Jim / crewzer

westbranch · July 2007

Re: Making up our own solar system!

thanks, I vaguely, very vaguely, remember that word now from the distant past.

And I thought that winter cold was a big problem, not so compared the high temps. summer or otherwise.
'Harsh conditions 'works pretty well.

Mind you what is winter without snow? just poor sledding!

Eric

crewzer · July 2007

Re: Making up our own solar system!

"Harsh conditions"... that'll work! 8-)

Regards,
Jim / crewzer

mike95490 · July 2007

Re: Making up our own solar system!

I want a solar system like the one I grew up in, with 9 planets, not the lousy 8 we have now.

Making up our own solar system!

Comments

Categories