how to find how much you need.........

bob1961 · March 2013

i'm in the process of saving a few more years to build a home, how do I find out how much watt's or watt hours it will need for a solar powered set up....or even how to find out if I want to go with an off grid set up from the start of the home build....reading here all kinds of info is making my head hurt and my eyes bleed

....how do I find out what is the best inverter, batteries and such, thanks....

Cariboocoot · March 2013

Re: how to find how much you need.........

If your head hurts and your eyes bleed you're getting there.

Issue #1: Should you go off grid?
How cheap will it be to go on grid? Usually it is the least expensive option. Sometimes it isn't. It all depends on the cost of the install, the hook-up fees, and the per kW hour charge.

Issue #2: How much power do you need?
Look on your present utility bill. Somewhere it should say how many kW hours you use in what time frame (30 or 60 days). That's a starting point. Then spend $30 on a Kill-A-Watt meter and start measuring everything you plug in. You're looking for energy hogs and phantom loads. You'd be surprised how much better it is to invest in new appliances that use less rather than coming up with ways to offset the consumption of the old ones.

Issue #3: What equipment do you pick?
All depends on what system design specs you come up with as a result of #1 and #2.

NorthGuy · March 2013

Re: how to find how much you need.........

If you have few years ahead, I would spend some time studying the subject and designing your system. It is very hard to learn everything in a single day. You need to spend time doing this. At the end, it'll be clear for you if you want it or not.

I've got interested in off-grid several years ago. I've done a lot of reading trying to understand how things work and find a system that I can get away with on my budget. I think I did, although it looked impossible in the beginning. It does take time.

BB. · March 2013

Re: how to find how much you need.........

One less expensive way to both learn and have something useful... Build out a small off grid system (such as 2-4 golf cart batteries setup as a 12 or 24 volt system with 400-800 watts of panels) to power your small loads (typically lighting, computer, radio, water pressure pump from cistern) that runs 24x7. And a propane fridge (from an old RV)--If you are not there "full time" *(i.e., less than 9 months out of the year, weekend building, etc.).

And get a good genset to run your power tools during the day... Possible a good Honda eu2000i for smaller tools (and backup battery charging for your solar system during poor weather), and a big guy (perhaps a cheaper 3.5-5kW) unit to run the occasional larger tools (planers, large table saw, well pump for cistern, etc.).

The generators if done correctly will not cost you too much in fuel and money for the time you are building the home (the small Honda may use 1-2 gallons of fuel per day).

If you try to use a 12kW genset for everything... Those things probably will consume over 1 gallon per hour just fired up, running a load or not.

-Bill

westbranch · March 2013

Re: how to find how much you need.........

as to your 'final ' solution, try drawing & laying it out on paper for what you think you will have, verify it against your new home-site, then redraw it with what you have site confirmed. As to size try planing out an install for your current house using the usage from your monthly grid consumption. Then look for things you can conserve on, in real life you need a Kill-o-Watt meter ~ $25 http://www.p3international.com/products/special/p4400/p4400-ce.htm

come back here and we will be glad to tune it up, or down, for you...

bob1961 · March 2013

Re: how to find how much you need.........

yeah I know running a generator while building is not an issue....ok right now i'm in a 70x14 mobile home that uses kero burning forced hot air, propane for stove and just lights, two PC's and tv junk in three rooms....yeah I know bout the lil phantom electric demons in house hold stuff that stay on when junk is turned off :roll: ....maybe if I post what my house spec will be and how many circuit/boxes it will have....i'm trying not to have any fuel burning devices for heat/hot water and cooking so I have no fuel delivery cost....

30' x 46' ranch style with full basement and attic access only....with 5 circulator pumps for the 5 zones
two electric tank less hot water heaters, hot water and baseboard heat ....
basic 15 amp outlets for bed rooms and living room about 20 boxes....
circuits are each bed room 3, bath room 1, living area/kitchen 1, basement 1 and kitchen counter area 1....
16' x 24' shop outside with its own small 10 circuit drop panel to run basic hand tools drill press and miter saw with a 220 outlet....

I think I have most there, ask away for any other info....

Cariboocoot · March 2013

Re: how to find how much you need.........

All electric? Off grid?
Prepare to say "ow".

Eric L · March 2013

Re: how to find how much you need.........

30' x 46' ranch style with full basement and attic access only....with 5 circulator pumps for the 5 zones
two electric tank less hot water heaters, hot water and baseboard heat ....

That's going to be a big set up and between now and the time you build it in a few years, you're almost certain to make many changes (the tankless hw heaters, for instance, pose a huge draw on the batteries/inverter relative to other possibilities like a solar thermal hw system).

Since this is still several years away, at this time, I would second BB's advice above to consider building a smaller "trial" system for now that might run a circuit in your current home. Among the advantages of doing so:

- you will learn first hand about the details of battery maintenance, battery cycling and balancing it with loads, the kind of solar power available at different times of the year at your location, what you can and can't expect, etc.

- it's more enjoyable to build a system at your leisure and without the risk of making a huge expensive mistake. This may seem trivial, but keeping solar enjoyable is important to having it work for you in the long term. And if it turns out it's not for you, then you'll find out before making a huge monetary commitment.

- you'll quickly get more interested in conservation because it's cool to figure out ways to squeeze the most from your little system.

If you do build a small system first though, you should realize that some parts might not transfer to your long-term project system. Even so, you'll probably find a home for them (all my little hobby solar system parts are still in use, either by me or by friends).

westbranch · March 2013

Re: how to find how much you need.........

OW,, OOOOOH that HURT

I suggest you start reading this thread http://forum.solar-electric.com/showthread.php?18459-Demonstration-of-Generator-Support&highlight=generator+support and make note of his equipment descriptions and his power sources...lots of good info for you running a NORMAL electric house

Photowhit · March 2013

Re: how to find how much you need.........

I don't know where your located, but photovoltaic heat is pretty much a nonstarter, and I'd rule out on demand electric hot water heater as well.

Other electric hotwater is possible, look into direct solar water heating and heatpump hot water heaters.

For heating your house, first look at reducing the need, by building a earth contact house, and use wood heater, wood is carbon neutral.

bob1961 · March 2013

Re: how to find how much you need.........

hey thanks guys for fast answers....yeah I know tweaking is always there to be tried....I used to be an auto tech so I know a battery electrical systems and I have my R/C hobby with charging/dis charging batteries and such....oh yeah my landlord pays for my utilities included in my rent, but she says it run just bout 200.00 a month with what I have in other post before....$2,400.00 a year seems like a lot plus add that each year at that cost makes one think there has to be a better way, lol....I also thought bout a big 500/1,000 gal propane tank for hot water and a hot water heat system and cooking....there for my electric load should be way lower them what I said before, so yeah lots of tweaking and changes to be looked at and be done....oh yeah my nickname my friends have given me is MacGyver....cause I can do so much with so little, that now everyone wants me to do everything with nothing, lol....right now i'm thinking of doing a little set up with a battery and an AC converter to run my fridge and little freezer I have when the good ol power goes out....and it goes out a lot up here in northeast PA....last summer with that sandy storm we had no power for 30 hours in summer heat....we had time to collect ice and coolers and only lost the door full of condiment's, no major meat and frozen stuff and what did defrost a lil was cooked up....I still will have a back up generator run on propane for when we lose power, but would like offsetting the electric cost the best I can....well sorry for a long reply and thank you once again as i'm still learning what can be done with wind and or solar power....

westbranch · March 2013

Re: how to find how much you need.........

Look into Solar Water heating with evacuated tubes.

her is an example from a Google search

http://shop.latitude51solar.ca/Evacuated-Tube-Solar-Collectors-s/38.htm

Photowhit · March 2013

Re: how to find how much you need.........

bob1961 wrote: »

...but would like offsetting the electric cost the best I can....well sorry for a long reply and thank you once again as i'm still learning what can be done with wind and or solar power....

So far "Off ZGrid" solar can't be done cheaper than the grid. It maybe under a $1 a Watt hour now, but grid tied system could be near cost effective and a real hedge against rising electric costs if that's where you believe we're headed. If you just want to have backup a genny is your best bet.

There are things you can and should do to make your new home, if scratch built, much more energy effiecent, minimum 2x6 walls, blown foam insulation, R44+ in the roof. Or earth contact home, which uses the earths near steady temperatures 3-4 feet down to help heat and cool the home, kinda like a geothermal heat pump, using the warmth or coolness of the ground to heat and cool the air.

northerner · March 2013

Re: how to find how much you need.........

westbranch wrote: »

Look into Solar Water heating with evacuated tubes.

her is an example from a Google search

http://shop.latitude51solar.ca/Evacuated-Tube-Solar-Collectors-s/38.htm

Worth considering yes, but also depends on location as well. With the current low cost of PV panels, solar PV is becoming more cost effective than Solar Thermal in certain circumstances. Check this out.

http://www.greenbuildingadvisor.com/blogs/dept/musings/solar-thermal-dead

how to find how much you need.........

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