For a minute there I thought I had to get off my couch, when all the while the fact is we don't have to do anything much but keep things afloat for just a few decades more! In fact, we'd best shut up about PO, because if our offspring finds out we knew about it all along, they'll turn and wring our necks come 2036!
Battery - I know I need one, I just havent figured out which one yet...
Of course all the mounting hardware and wiring, but is there anything else I would need to make this system work?
Also, If I plan on supporting the bare minimum electrical needs for my house, which is about 1kw hour per day. I got that number by doing (5)11watt light bulbs to be turned on for about 5 hours per day and (1)30 watt water pump (for the aquaponics system) to run for 24 hours per day. Is this right? How would I figure out how much storage capacity I need in my batteries?
Please help, I'm so lost.... _________________ Tired of high gas prices? Then stop driving to work, duh..... Learn to Work from home
You don't "need" a battery. You "choose to have one" or not. It depends on what you are trying to do. Batteryless systems are more common than systems with batteries.
My advice is:
1. Start with conservation - cut your use to the bare minimum
2. Plan a system for that level of use
You will spend a lot less powering a minimal, efficient load than an inefficient, "non-negotiable lifestyle" load.
The more you research before you proceed the more confidence you will have that it's all going to do what you want.
SolarDave _________________ Posted from a Solar/Pedal Powered Computer
Posted: Thu May 15, 2008 1:32 pm Post subject: Re: Anyone here know grid tie systems?
Thanks for the link, that diagram right at the top was exactly what I was looking for.
Now I can understand how things work a little better and move forward. _________________ Tired of high gas prices? Then stop driving to work, duh..... Learn to Work from home
Posted: Thu May 15, 2008 2:02 pm Post subject: Re: Anyone here know grid tie systems?
Ok so wouldnt it be more cost effective to design the solar system to be separate from the existing electrical system?
What I mean is, instead of spend a ton of money converting everything to a 120v system, I could wire in a separate 12v system inside the house.
I could light my entire house with 12v LED lights which only consume 2.5 watt of electricity.
I have everything else taken care of; underground food storage, solar cooking, wood stove for heating.... Why would I want to convert the power to 120v for the entire house?
If I ever wanted to run a lap top or charge AA batteries or power a radio (assuming someone is still broadcasting) or anything like that I could plug in a simple $50 power inverter that they sell for use in cars.
Am I missing something or is it really a whole heck of a lot cheaper to wire a 12v system into my house?
One possible problem will be finding a 12v pump capable of producing at least 50gph at 5 feet of head.... _________________ Tired of high gas prices? Then stop driving to work, duh..... Learn to Work from home
Joined: Jan 03, 2005 Posts: 1159 Location: western Wisconsin
Posted: Thu May 15, 2008 2:29 pm Post subject: Re: Anyone here know grid tie systems?
To answer a couple of your initial questions, you will also need a charge controller if you are using batteries, and an inverter. The MidNite Solar E-Panel MNE125STL OutBack is just a mounting and circuit breaker panel for an Outback inverter, which is an additional $1800 or so. Then there are disconnects and circuit breaker panels needed at various places in the system. The articles that SolarDave mentioned will help you see what else is needed. You may want to subscribe to Home Power as they usually have good articles about home systems, their components, cost, and why certain items were chosen.
Otherwise, going to an energy fair and taking some classes would be worth the time and money. It isn't as easy as it seems to design and install a PV system, especially if it needs to comply with electrical and building codes. System designers and installers earn the money that they charge.
Posted: Thu May 15, 2008 3:05 pm Post subject: Re: Anyone here know grid tie systems?
WisJim wrote:
It isn't as easy as it seems to design and install a PV system, especially if it needs to comply with electrical and building codes. System designers and installers earn the money that they charge.
Design work isnt rocket science, I shouldnt have a problem conforming to the guidelines in the 2006 IBC or IEC.
I understand that designers are the experts in their prospective feilds, I design HVAC, plumbing and mechanical systems for a living. Designing any system is fun and interesting to me, so I will stick with the DIY method. Installing is where I lack motivation....... _________________ Tired of high gas prices? Then stop driving to work, duh..... Learn to Work from home
Posted: Thu May 15, 2008 3:12 pm Post subject: Re: Anyone here know grid tie systems?
A grid-connected system can be expensive to install. Permits are required and the work needs to be done by a licensed electrician. There are also restrictions on the types of equipment you can install in a grid-connected system.
But, it seems that you are more interested in setting up an off grid system that can function in parallel or act as a backup during times when the grid goes down.
For your first attempt at an off grid system, it would be better to start out small but have a few key items in place that will make further expansion easier and less costly.
So here a few things to consider:
Converting major energy users to DC will allow you to get by with fewer panels and batteries. While it may take a while to switch things over to DC, installing a DC system from the start will save money.
A 24 volt system is better for running long wires carrying DC current to different areas of your house. A separate DC breaker box equipped with DC circuit breakers is generally a good idea. Unforeseen events may occur such as if a rodent chews through a power cable and starts an electrical fire.
Spend a little extra on a good battery charger such as the Outback MX-60.
Avoid spending a lot on batteries when you are first setting up your system. Sam's club 6 volt golf cart batteries will do the job for a few years and are 1/2 to 1/3 the cost of regular deep cycle batteries. But if you can obtain a set of used (but good) AGM forklift batteries, buy them.
Invest in an amp hour meter with a current sensor shunt and avoid draining the batteries below 80% amp hour capacity.
Get an inverter with standby mode, which only draws 3 watts or less when on standby. You can leave it in standby mode and always have ac available when needed. Setup a separate breaker box and main AC outlets for the inverter.
Your pump and refrigerator are probably the biggest energy users. For the refrigerator, how much refrigerated space do you really need?
Last edited by tsakach on Thu May 15, 2008 3:26 pm; edited 1 time in total
Posted: Thu May 15, 2008 3:26 pm Post subject: Re: Anyone here know grid tie systems?
For the intial system I dont plan on hooking up the refrigerator. I need the pump for circulating water in the aquaponics system.
This first system I set up will be to just cover the minimum things, lighting the house when it is dark and pumping the fish water.
I dont need plumbing, it is definately the next thing to take a look at. For now I want to provide lighting and power for the pump that helps provide food.
With a 24 system, wouldnt the light bulbs be more difficult to come by? especially post peak oil if everything falls apart?
I live right down the road from 4 junk yards with hundreds of cars, they all run off 12v systems, so spare/replacement lights would be easier to get for a 12v system.
My house isnt very large, only 1200 sqft. I could mount the solar panels near the center of the house, put the breaker box/ batteries right below it in the attic, then run the wires. Each run would probably be 30 ft max, with the exception of the fish pump... It may go on a separate system...
What are the benefits to a 24v system? _________________ Tired of high gas prices? Then stop driving to work, duh..... Learn to Work from home
Posted: Thu May 15, 2008 3:48 pm Post subject: Re: Anyone here know grid tie systems?
burtonridr wrote:
This first system I set up will be to just cover the minimum things, lighting the house when it is dark and pumping the fish water.
Sounds like you need a smaller system rather than rewiring the house for DC and running everything from solar. A 40-80 watt panel, charger and 2 6 volt batteries would work fine. Lighting is easy but I would hook the fish tank pump to a multimeter and measure the current it needs. Constant loads like this are difficult keep running.
burtonridr wrote:
What are the benefits to a 24v system?
24 volt systems or higher are better for larger systems or when long wire runs are needed.
The main benefit of 24 volts is that less energy is lost in the wiring. You can find tables that show wire thicknesses and the corresponding voltage drops for different thicknesses and lengths. 12 volts works fine for automotive applications since the wire runs are short. Trucks, aircraft and industrial DC generally use 24 or higher.
Another benefit of 24 volts is that you can reduce the number of parallel chains of batteries and panels. If you have a lot of 12 volt batteries connected in parallel they tend to discharge at different rates over time and energy will be lost when current is flowing between batteries rather than to the loads.
You can still tap off 12 volts from a 24 volt battery pack or step the voltage down efficiently with a transformer. I use a combination of 24v for main current flows and 12v to power lights and smaller appliances.
Last edited by tsakach on Thu May 15, 2008 4:27 pm; edited 1 time in total
Joined: Oct 16, 2004 Posts: 1377 Location: Appalachian Foothills of Virginia
Posted: Thu May 15, 2008 3:54 pm Post subject: Re: Anyone here know grid tie systems?
It helps to chart out your eventual goal for your solar PV system. That way, you don't spend money on components that limit you or require spending much more to upgrade to larger components.
Do you eventually want to;
- Run most of you lights?
- Run your refrigerator?
- Power computers?
- Power a well pump?
- Other?
You could run everything via DC or AC, though most of your appliances would require replacement and the choices are much fewer.
Posted: Thu May 15, 2008 4:30 pm Post subject: Re: Anyone here know grid tie systems?
skyemoor wrote:
It helps to chart out your eventual goal for your solar PV system. That way, you don't spend money on components that limit you or require spending much more to upgrade to larger components.
Do you eventually want to;
- Run most of you lights?
- Run your refrigerator?
- Power computers?
- Power a well pump?
- Other?
hmmm........
A refrigerator/freezer would be nice, my fear is that everything is falling apart much faster than I anticipated and I need to provide my family with the basics first. A lighting system is going to be essential, I prefer electrical lighting over candles or lanterns for safety and convenience.
I guess in the future I could always add the 120v system to run those things, and continue to use the 24v system for lighting.
Installing a 24v system independent from the 120v system would not limit a future 120v system.
That is a good point to consider _________________ Tired of high gas prices? Then stop driving to work, duh..... Learn to Work from home
Joined: Nov 15, 2007 Posts: 236 Location: US East Coast
Posted: Thu May 15, 2008 6:15 pm Post subject: Re: Anyone here know grid tie systems?
OK for my broken record.
I suggest that you also look at yacht electrical system design. It may or may not be applicable to your situation. If you are set on tying to the grid then probably not.
If you want to live in a small footprint, off grid, then this is a good resource. Refrigerator/freezer is a big power drain on boats. They tend to make super insulated boxes that run from a plate. Not that hard to do, especially on land when you have lots of room for thick insulation.
It's all about making a budget and then designing to it. Just like money.
Google Nigel Calder, great resource. Enough to make your head hurt. _________________ When going through hell, keep going! Churchill
Nothing is ever lost by courtesy. It is the the cheapest of pleasures, costs nothing, and conveys much. E Wiman
I know there’s no solution, so I just enjoy what’s here and I enjoy the journey G Carlin
Joined: Aug 07, 2005 Posts: 302 Location: Columbia, MO
Posted: Thu May 15, 2008 8:17 pm Post subject: Re: Anyone here know grid tie systems?
burtonridr wrote:
I live right down the road from 4 junk yards with hundreds of cars, they all run off 12v systems, so spare/replacement lights would be easier to get for a 12v system.
You can always wire two bulbs in series in a pinch.
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Then stop driving to work, duh..... 
