I am so new I haven't even started, Series Question

Re: I am so new I haven't even started, Series Question

shmockey wrote: »

I just moved to a new house about a year ago and have been running my garage off from extension cords due to it not having electric. I have had a few Electricians come out and look at putting some electric out there and they say that it is too far away from the house and they would have to run a whole new service. I am not questioning them.

Realistically--how much are you willing pay to put power to the garage--people here, when the look at the price of solar, many times bite the bullet and spend the money to lay in a 1/2 mile of electrical service instead of installing solar.

Would you use a 120/240 volt 40-120 amp service if you had one--or are you really happy with enough power to light a 50 watt light bulb a few hours a day?

No right or wrong answer (and not a trick question)--Power use is extremely personal--and one person's 50 watts * 10 hours a day (500 watt*hours or 0.5 kWhrs per day)--is somebody else's 10-50 kW per day usage.

What I want to do is buy one of those all inclusive 3 or 4 15 watt panel beginner solar power systems and run my radio, lights and pellet stove for a few hours a night when I am out there.

Unless your power needs are tiny (running a single 13 watt CFL for a few hours a day)--those 15 watt panels are not going to help you much at all...

Just to help you size the system... Let's say you are near Williamsport PA and get 2.3 hours of full sun per day for December (on average it is 4.18 hours of sun for a panel tilted at latitude).

A pellet stove will use around 20-42 watts. Let's call it 2x13 watt CFL's, a 10 watt radio--all for 4 hours per night (in December):

• (42 watts + 2x13w + 10 watt) * 4 hours per night = 312 Watt*Hours per day

And, assumed fixed panel at latitude solar array, and 0.52 end to end efficiency (from solar panel in to AC Inverter out, using flooded cell batteries):

• 312 WH * 1/2.3 hours of sun * 1/0.52 eff = 260 watts of solar panel for December

Battery bank size--assume 12 volts and nice 300 watt true sine wave inverter (0,85% efficient), 3 days of no sun, 50% maximum discharge from battery bank, and 12 volt flooded cell battery bank:

• 312 WH * 1/12 volts * 1/0.85 inv eff * 3 * 1/0.50 = 184 AH battery bank @ 12 volts

Of course, this is based on my guesstimate of your usage pattern for dead of winter (December). You may need a backup power source (generator or extension cord if you have a week of bad weather).

For solar panels, you should look at large ones (100 watts or larger) because they typically have the best pricing.

My big questions are, if I buy one of those and I decide to put more panels up do I have to stay with only 15-watt panels or can I run a larger panel with them? Second whatever panel I would be able to run, what is the way to run the new panels?

To add panels... When adding solar panels in parallel--the Vmp should match within 10%. When adding solar panels in series--the Imp should match within 10%.

As you can see--you may be looking at 150 watt panels instead of 15 watt panels--but the electrical stuff remains the same--Just bigger.

I do know that I will have to possibly change the charge controller if I go to high with the incoming amps.

For a 312 watt system, you are probably looking at an ~30 amp 12 volt charge controller.

There are still a lot of details to discuss-but you are looking at, roughly (for nice quality equipment):

$1,000-$1,500 for solar panels
$200-$300 for a charge controller
$250 for a TSW 300 watt inverter
$140-$250 for battery bank
$300 for fusing, breaker, panel rack, misc. stuff

Of course--a lot of this depends on how much power you really need, can you buy used, use a MSW inverter, and when you need it (summer/winter/etc.). We recommend that you get something like a Kill-a-Watt meter to measure your total daily estimated loads... Also, the K-a-W meter is very handy around the home for conservation too.

Or you can get a Honda eu2000i 1,600 genset for less than $1,000 and run 400 watts for around 15 hours on 1.1 gallons of gasoline...

Or, revisit the electrician or DYI to get power to your shed (trench in some direct burial cable and get 15 amps of 120/240 at the garage.

Questions?

-Bill

Re: I am so new I haven't even started, Series Question

Scott,

Don't get too suck on "renewable" being green... The batteries will need to be replaced every 3-8 years or so (another couple hundred dollars--more or less).

As an educational system--the small solar are very nice. If you have portable uses (RV, Camping, Cottage)--keeping it easy to move can be nice too (park your trailer next to the garage and draw power during the winter, etc.).

In the end, it is not hard to see that you are spending almost $1-$2+ per kWhr for the solar RE off-grid system... The batteries age if you don't use them, and age faster if you do (ye 'old catch 22).

Don't feel bad about asking questions--there would be almost nothing to read here if there where no questions...;)

Regarding things to read:

Home Power Magazine

FL SUN wrote: »

This is a link to a PV textbook I find very informative. It was a requirement for the FL contractor's exam I took last month. It even has a very good interactive CD with a bunch of informative extras. A quick search on-line shows this book goes for about $75.00 USD everywhere.

Don't forget nothing compares to OJT when it comes to installation. It's always best to apply in the field what you've learned from a good textbook first.
http://www.powells.com/cgi-bin/biblio?show=HARDCVR%20W/COMP%20MEDIA:NEW:9780826912879:75.00

TnAndy wrote: »

Rick,

Here a good "textbook" on solar......it actually IS a textbook for some solar courses, and is set up that way with practice questions at the end of each chapter, but it's also a good self guide as to the basics of components and how they mesh together to make a system. Worth the money, IMHO.


Solar Book Here

From our Host's Webstore:


Book - The New Solar Electric Home
The New Solar Electric Home book, by Joel Davidson 2008 Edition. The Complete Guide to Photovoltaics ...

Some information on NEC and how it applies to solar power:

PV and the 2005 NEC -- Reference Document

And, of course, the NEC Code Book (current edition or version that is used by your locality).

I have also created a thread with lots of random solar information and links (projects, information, how to, and how not to, etc.). You might cruse through it and see if there is anything of specific interest to you.

-Bill