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Post by somuchtodo on Apr 8, 2013 7:08:21 GMT -7
I'm wanting to get a small solar set up in place. I'm considering wiring a portion or all of my basement for low voltage lights, refrigerator, freezer, etc. My thoughts are in a power out scenario we could live out of the basement which would be easy to heat/cool and still have some low voltage appliances we could feed with solar and a battery bank. I guess I have a camper set up in my mind. Is this a reasonable thought or should I go with and inverter and stay standard? I'm trying to minimize the size and cost of the solar set up I need.
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Post by solargeek1 on Apr 8, 2013 8:17:59 GMT -7
PM Marc and TJ. They will know what you need/want. Also do a search here as I think this has been covered in answer to a question by DINK or someone else.
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Post by somuchtodo on Apr 8, 2013 15:21:53 GMT -7
PM Marc and TJ. They will know what you need/want. Also do a search here as I think this has been covered in answer to a question by DINK or someone else. I'll PM them for sure if they don't respond in this post. I looked through the other posts but couldn't specifically find something on avoiding a converter and using low voltage appliances and lighting only. I guess I'm not sure if it's really feasible or reasonable to take the low voltage route for a basement. I'm not looking to go completely off grid unless forced to but wanting to be able to have some luxuries like a small refrigerator and freezer if the grid goes down. I'm wide open to ideas/suggestions in this pursuit. |
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Post by missasip on Apr 8, 2013 17:39:59 GMT -7
The issue with using low voltage dc is the wire size, voltage drop.. If your wire runs are very long then your fighting voltage drop. Buying larger gauge wire these days can be prohibitive price wise. I tired dc voltage but quickly went to 120 ac with a small inverter. But I was only running a small fan, led lights and a small tv/dvd player. Generally in a camper/rv lights are the only thing that gets much run time, as batteries getted drained pretty fast. Now that's just talking about basic rv setups. You can rev up your camper if you have resourses to use....   Keep us in the loop as you persue this. I agree marc and TJ are the experts. Good luck. Jimmy |
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Post by tjwilhelm on Apr 9, 2013 5:23:21 GMT -7
You can set up a solar-PV system to provide just about any level of electric power you want or need. Yes, you can use "low-voltage," DC appliances, too; but, as Jimmy pointed out, low-voltage often means high-current, with the accomanying need for larger AWG wiring. Also, low-voltage, DC appliances can sometimes be a bit expensive. Here are a few thoughts:
1) Do you have a proper "solar window" -- no shade on the potential location of your solar-PV array, from 9a.m. till 3p.m., from December 21st till June 21st?
2) What specific loads/appliances do you intend to power with your low-voltage, DC system? You should find and assess these appliances before you go any further. How much do they cost? How efficient are they? Are they appropriate to your needs?
3) Not only will your low-voltage wiring need to be sized to keep your voltage drop to about 1%, but you will also need to use DC-rated disconnects and overcurrent protection. FYI, Square-D QO and QOU breakers are listed for up to 50VDC. Also, (if my memory is correct!) I think GE disconnects are dual rated for both AC and DC service.
If you find a list of specific DC loads you want to use, and if you will post that list here in this thread, I can walk you through a specifc, solar-PV system sizing and design. I'd bet Marc will be willing to pipe in, too.
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Post by somuchtodo on Apr 9, 2013 12:19:25 GMT -7
Thanks tj and Jimmy. It sound as if there may be no advantage in cost and efficiency to go low voltage. Are there any good turn key type set ups out there? I'm not looking to power a whole house but maybe a freezer, refrigerator and some small appliances plus build up a small battery bank for night use.
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Post by tjwilhelm on Apr 9, 2013 14:16:05 GMT -7
Just a thought...unless your house is "all-electric" (electric range and oven; electric water heater; electric furnace; electric clothes dryer, etc.), then the list of loads you described is just about the entire electric load list of a normal household: lights, fridge, freezer, and small appliances.
When I sell and install a stand-alone, battery-based solar-PV system, I typically suggest the following, in this order:
1) Conserve, conserve, conserve...make all your electric loads as high-efficiency as possible; and,
2) convert all your thermal loads to a storable fuel: LPG, wood, etc.
Another FYI...using DC loads, if properly designed and installed, can be more efficient than using AC loads. This is because the process of inverting the low-voltage DC into 120vac is not 10% efficient. That said, your typical motor-home appliances are not necessarily very efficient at concerting that DC electrical energy into the final form of energy you're after; and, they can be a little pricey compared to typical AC appliances. Making wise chpices here involves looking at your entire system and situation, including the cost and efficiency of your appliances and other loads.
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Post by somuchtodo on Apr 9, 2013 17:34:45 GMT -7
Just a thought...unless your house is "all-electric" (electric range and oven; electric water heater; electric furnace; electric clothes dryer, etc.), then the list of loads you described is just about the entire electric load list of a normal household: lights, fridge, freezer, and small appliances. When I sell and install a stand-alone, battery-based solar-PV system, I typically suggest the following, in this order: 1) Conserve, conserve, conserve...make all your electric loads as high-efficiency as possible; and, 2) convert all your thermal loads to a storable fuel: LPG, wood, etc. Another FYI...using DC loads, if properly designed and installed, can be more efficient than using AC loads. This is because the process of inverting the low-voltage DC into 120vac is not 10% efficient. That said, your typical motor-home appliances are not necessarily very efficient at concerting that DC electrical energy into the final form of energy you're after; and, they can be a little pricey compared to typical AC appliances. Making wise chpices here involves looking at your entire system and situation, including the cost and efficiency of your appliances and other loads. Okay. I think I'm on the right page. We're going to be relocating and are planning to build. Wood burner in the basement Natural gas/propane oven stove Hand pump water well (in the basement if possible) These are the items I'd be interested in powering with solar: Freezer in the basement Small refrigerator in the basement Geothermal heating/cooling |
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Post by tjwilhelm on Apr 9, 2013 19:03:43 GMT -7
The freezer and small fridge are a piece of cake; but...
WOO-HOO!!! That "geothermal heating/cooling" system is going to be a BIG load. Of course. that depends on the size of the space you are heating/cooling, and the thermal efficiency of the building envelope (how well insulated it is).
I know of one solar installer in New Jersey who was selling solar-PV system to "geothermal" owners. Typically, it required a 10KW PV system to mostly cover the power needs of the "geothermal." Also, FYI, I had a friend near here install a "geothermal" system on his house and it cost a tad over $15K!
If you're going to be building from scratch, I'd be researching topics like:
1) Zero energy houses;
2) Passive solar architecture;
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Post by somuchtodo on Apr 10, 2013 15:00:23 GMT -7
I'll check into the zero energy and passive solar options. Thanks for the info. across the board, it is very helpful as I'm in the mental conception phase of building. +1 for all the help!!!!
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Post by marc on Apr 10, 2013 18:33:06 GMT -7
As usual, TJ is right on the money (and he knows way more than I do about this) There is always a collision between “what I want” and “what I want to pay for.”
Step ONE is always to sit down and create a realistic daily energy budget – then find a way to cut it in half. Seriously, I have customers who have spent ten times what they could have, if they had been willing to flex a little in what “they HAD to have.” If you have a bunch of money to throw out, TJ already said that he can do pretty much anything you want! But you had better be ready to spend more than you paid for your new car, or two, or three.
I personally like low voltage DC setups (for very small systems) that minimize the use of an inverter because of the inherent inefficiency that TJ already identified. BUT, for some things you will likely want to go 120 VAC (or 240v) via an inverter. My leaning toward 12v/24v DC is based on ultra simplicity for very small systems on a thin wallet to start. As TJ said, low voltage/high efficiency appliances are expensive, but a few lights, a fan and laptop/phone charging is easy.
With this subject you REALLY have to start by identifying a $$ budget/needs ratio. So, let’s do it this way:
Pick a dollar amount and we can collectively see if we can collectively build a workable system!
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Post by tjwilhelm on Apr 10, 2013 22:56:36 GMT -7
Good idea, Marc!
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Post by geron on Apr 11, 2013 3:51:25 GMT -7
I'm all ears on this one!!! Build away.
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Post by somuchtodo on Apr 11, 2013 13:50:15 GMT -7
As usual, TJ is right on the money (and he knows way more than I do about this) There is always a collision between “what I want” and “what I want to pay for.” Step ONE is always to sit down and create a realistic daily energy budget – then find a way to cut it in half. Seriously, I have customers who have spent ten times what they could have, if they had been willing to flex a little in what “they HAD to have.” If you have a bunch of money to throw out, TJ already said that he can do pretty much anything you want! But you had better be ready to spend more than you paid for your new car, or two, or three. I personally like low voltage DC setups (for very small systems) that minimize the use of an inverter because of the inherent inefficiency that TJ already identified. BUT, for some things you will likely want to go 120 VAC (or 240v) via an inverter. My leaning toward 12v/24v DC is based on ultra simplicity for very small systems on a thin wallet to start. As TJ said, low voltage/high efficiency appliances are expensive, but a few lights, a fan and laptop/phone charging is easy. With this subject you REALLY have to start by identifying a $$ budget/needs ratio. So, let’s do it this way: Pick a dollar amount and we can collectively see if we can collectively build a workable system! Alright, I'm game. Going back to my original thought of having to live out of a basement in a grid down situation. What could I do with $10k? My priorities in order would be: 1. Freezer (small chest style) 2. Fan 3. Small refrigerator 4. Small hot water heater (maybe a 30 gal.) 5. Lighting (a couple of overhead lights) |
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Post by tjwilhelm on Apr 11, 2013 15:09:10 GMT -7
Two things... I'm going to split your list and I'm going to recommend two different energy sources.
Put the water heater into a group by itself and heat it with a solar water heating PANEL (and make the tank bigger).
Now I need to know where you are, approximately. State? Section of State? This will help me find your solar resource and the average installed system cost in your area.
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