first post - help with connecting panel and good build thread

minisolar

Hey all,

I have been looking into solar for my off grid tiny cabin. I have yet to plan/buy my solar parts - which I will soon with the kind help of this forum but I do know in general how I want to run my system.

I am not very savvy in electricity which is why I am using my father-in-law's help with wiring. We have almost finished wiring the cabin - regular AC.

We used this panel - http://www.homedepot.com/p/t/100184775?storeId=10051&langId=-1&catalogId=10053&productId=100184775&R=100184775#.UgkR0ZLUk3Q

I will eventually want to - have the cabin run of my inverter (of course) or in case I have issue with my solar - off my honda 200 gini. Also, I would like to charge my batteries in case of sun issues with my gini.

How should I wire the feed into the panel? can someone show photos or explain how they did it? (I bought those charger inlet to hook up the generator btw).

Also, can someone share some good, long, and photo heavy builds here that are similar to what I want to do?

Thanks!!!!

icarus

Re: first post - help with connecting panel and good build thread

Do your self a favor, and try real hard to define your loads, both peak and total daily. All design considerations stem from the loads. Any other regimen is square pegs and round holes. Loads define battery size, battery size defines PV and CC size, and inverter size.

Welcome to the forum, and keep in touch,

Tony

minisolar

Re: first post - help with connecting panel and good build thread

Hey tony,

I know that I will need to do that. I will soon enough but I want to first finish wiring up the cabin so I can start concentrating on my solar system. Can you help with how to wire the pats for the inverter and such... ?

BB.

Re: first post - help with connecting panel and good build thread

If you want a good place to look at a DIY type system that was well done, I would look though 2manytoyz's website:

http://www.2manytoyz.com/

At the bottom of his website, he has lots of conservation and solar projects -- and pictures too.

If you are going to use AC at the cabin (usually, my recommendation), get a Kill-a-Watt type meter. And measure all of the loads you want to run.

You are after Average Watts and Watt*Hours per day (or kWH per day) per appliance/tool/etc...

To give you an idea...:

1. 1 kWH (1,000 Watt*Hours) per day--Small cabin, lights, water pump, laptop computer
2. 3.3 kWH per day--Add a refrigerator and an electrical clothes washing machine (close to "normal" electrical life with lots of conservation)
3. 10 kWH per day--A very efficient home with electrical appliances, well pump, etc. and propane/alternative fuel for heating/hot water/cooking
4. 33 kWH per day--Typical north American home usage--Possible electric cooking and/or electric hot water (without much conservation)
5. 100 kWH per day--Full A/C in hot climate, a lot of power usage.

The first two--Pretty easy and cost effective systems.

The third one--Think the price of a very nice high end new car.

The last one--Can be done, but usually a business or other a-typical home/installation.

Plan on your off grid power costing in the range of ~$1 to $2+ per kWH -- Or ~10x the cost of utility power--and 5-10+ years of power bills mostly paid up front at install.

That 1 kWH (1,000 WH) per day system--33 kWH per month--equivalent of $33-$66+ per month power bills

3.3 kWH per day is ~100 kWH per month, equivalent to ~$100 to $200+ per month power bills... Get an idea why conservation and planning your power needs is critical? This system would cost you somewhere (real rough guess) around ~$15,000 to $30,000 to install... It may cost you less, or it may cost you more--Too many variables at this point to be more precise.

-Bill

BB.

Re: first post - help with connecting panel and good build thread

Your first choice is 120 VAC or 120/240 VAC power system.

A 120 VAC system makes sense for most off grid power smaller homes/cabins. 240 VAC only makes sense if you have a large/deep well pump and/or need to ship power a considerable distance (remote well pump, out buildings)... If you need A/C or Electric Hot Water (typically heat pump system), 240 VAC may be needed.

For AC wiring--You can get 3 conductor + Ground ROMEX cables... The Black+Red hot wires are split phase (120/240 VAC) with a common Neutral. This works fine for 120/240 VAC split phase inverter and generator installations.

But if you go with a 120 VAC only installation, you cannot use 3+1 ROMEX wiring. The Black+Red are the same phase, and they add up and can over current the shared neutral wring.

Run a dedicated Hot+Neutral to all of your AC loads to when installing a dedicated 120 VAC system.

Are you really "tight for cash"?... I normally recommend a TSW (true Sine Wave AC inverter) for off grid power. But they are a lot more expensive vs the "cheap" MSW (modified square wave) inverters.

If you go with MSW inverter--Your AC Neutral wiring cannot be grounded in the Main panel--MSW inverter AC output wiring (usually) needs to be "floating" and must use an Isolated Neutral bus bar in the main panel.

TSW (True Sine Wave) inverters usually have "isolated" AC outputs and will run very nicely with ground bonded AC neutrals (typical North American home's wiring standards).

All About Inverters
Choosing an Inverter - Home Power Magazine

Is that more along the lines of the answers you were looking for?

-Bill

Cariboocoot

Re: first post - help with connecting panel and good build thread

Some of how the wiring is done will depend on what you ultimately choose for an inverter and generator, which depend on what the load requirements are.

The reason being some inverters have built-in transfer switches that will automatically connect loads to the generator input when it is running. Some do not, and will require an external switch of some sort.

Otherwise the AC wiring from the panel to outlets/loads is standard household protocol. The changes are made at the source of the power feeding the distribution panel.

Likewise the DC wiring side will be dependent on what inverter is chosen.

minisolar

Re: first post - help with connecting panel and good build thread

Cariboocoot wrote: »

Some of how the wiring is done will depend on what you ultimately choose for an inverter and generator, which depend on what the load requirements are.

The reason being some inverters have built-in transfer switches that will automatically connect loads to the generator input when it is running. Some do not, and will require an external switch of some sort.

Otherwise the AC wiring from the panel to outlets/loads is standard household protocol. The changes are made at the source of the power feeding the distribution panel.

Likewise the DC wiring side will be dependent on what inverter is chosen.

I see... I made a list of electric items in my cabin, their individual wattage, and how long I will use it for... For example: cfl light outdoors - I estimated I will use it for 3 hours during my weekend stay. The bulb pulls 23watts. So I will use 69 watts for that. I did this with every item on my list and the total came to be 2035 watts.

Does that help with understanding my usage?

I rather plan with 25% buffer so lets say I will use 2500 watts.

Again, I will use this and then now be in the cabin for 2 weeks. Although we noticed that we actually use the cabin 3 weekends out of the month and not 2 as we planned... we just enjoy it.

Cariboocoot

Re: first post - help with connecting panel and good build thread

minisolar wrote: »

I see... I made a list of electric items in my cabin, their individual wattage, and how long I will use it for... For example: cfl light outdoors - I estimated I will use it for 3 hours during my weekend stay. The bulb pulls 23watts. So I will use 69 watts for that. I did this with every item on my list and the total came to be 2035 watts.

Close, but not quite. 23 Watt bulb used for 3 hours is 69 Watt hours. This is not the same as Watts and you need to keep track of that difference carefully.

So let's say you need 2500 Watt hours AC. There is an efficiency rating for any given inverter. if this is 90%, then that 2500 Watt hours AC becomes 2778 Watt hours DC.

Then the inverter itself will consume power. It makes a big difference which inverter, and that's why you need to know maximum Watt load. A Morningstar 300 Watt inverter uses 6 Watts. An Outback 3500 Watt inverter uses 20. Others use differing amounts depending on their design.

Let's say you have no total loads that will exceed 300 Watts and pick the MS inverter. If it is on constantly it will draw (6 * 24) 144 Watt hours DC. That gets added in, and the grand total the batteries have to supply in a day now comes to 2922 Watt hours DC. Call it 3 kW hours.

This is important to picking a battery Voltage too: divide 3000 Watt hours by 12 and you get 250 Amp hours used. That means a minimum battery of 500 Amp hours, which would supply that much without going below 50% SOC.

At that point you might re-think the system Voltage so as to use batteries more efficiently, and weigh that off against the inverter choices (the MS 300 doesn't come in a 24 Volt version). Or you may want to revisit the loads and see if they can be shaved down a bit so that you only need 450 Amp hours (because that would be two parallel strings of Trojan T105's for example).

Once the inverter and batteries have been determined you can calculate what is needed to recharge those batteries. At any system Voltage charge controllers are rated at their maximum output current. Since you want about 10% peak charging current and the largest controller will handle 80 Amps any time you have a battery bank going above 800 Amp hours you should consider going up in Voltage. Otherwise you'll need to to use two controllers.

Is any of this helping?

Again, I will use this and then now be in the cabin for 2 weeks. Although we noticed that we actually use the cabin 3 weekends out of the month and not 2 as we planned... we just enjoy it.

Enjoy it while you can. We thought we would be able to spend a lot more time at ours in retirement, but things are not working out that way.

minisolar

Re: first post - help with connecting panel and good build thread

Thank you for this very informative post. I will re-read again today to see if I truly understand it.

Then can you now tell me how to prepare the connection on the panel for the future inverter?

Cariboocoot

Re: first post - help with connecting panel and good build thread

minisolar wrote: »

Thank you for this very informative post. I will re-read again today to see if I truly understand it.

Then can you now tell me how to prepare the connection on the panel for the future inverter?

Off-grid panels do not connect to the inverter. They connect to the charge controller. The controller connects to the batteries. The batteries connect to the inverter. It's like three separate but interacting circuits.

What you have to do to connect them is again dependent on what equipment is chosen, what Voltage and current is expect in each circuit, how far apart the units are, et cetera. Trying to build any one segment of the system without knowing what the whole will eventually be is frustrating and disappointing. This is why it is so difficult to expand a system after its initial installation.

Or "Until you know what you're dealing with you don't know what you're dealing with."

minisolar

Re: first post - help with connecting panel and good build thread

Then what other info do I need to provide you with so you can tell me?

I heard that there are some inverter & charger in one that make your life easy. Again - I would appreciate if you can just make a recommendation on the components. When you understand what I will want to use - tell me how you will build the system

Cariboocoot

Re: first post - help with connecting panel and good build thread

minisolar wrote: »

Then what other info do I need to provide you with so you can tell me?

I heard that there are some inverter & charger in one that make your life easy. Again - I would appreciate if you can just make a recommendation on the components. When you understand what I will want to use - tell me how you will build the system

There are indeed some units that have built-in solar charge controllers. Avoid them; they tend not to be well-thought-out and won't necessarily fit with your system needs. Do not confuse these with inverter-chargers, which are inverters with built-in AC powered battery chargers.

So what you want to do is itemize your AC and DC loads. If possible measure the actual power usage of the AC loads with a Kill-A-Watt meter (manufacturer's info tends to be highly inaccurate). DC is likely to be more straight-forward: if it says 'X' Amps @ 'Y' Volts it probably really is 'XY' Watts.

Then determine how long you use each item per day. This is probably the worst part. Running loads through the K-A-W under normal use for a few days gives fairly accurate numbers. Trying to time yourself when using things ... you get self-conscious about it and leave stuff on too long or turn it off too soon.

These two things together will determine your daily Watt hours, which is necessary to determining battery bank size.

Figure out what is the most you'll have on at any one time. This is your maximum Watts and is needed to size the inverter and battery bank.

Once you have these numbers you can look at what would be best for system Voltage, battery bank and inverter size, and what would be required to recharge it.

Yes, I know: it is a lot to think about. There are many different ways of achieving the same goal, and picking the one that's best for you ultimately comes down to your choice.

minisolar

Re: first post - help with connecting panel and good build thread

No DC at all. Only AC. I have already calculated my power needs. I will only use this cabin from Friday afternoon until Sunday afternoon - once every other weekend. So 48 hours a weekend every other weekend....

I am attaching an image from the excel sheet i made that calculates the loads. So this is how much power I will need/use in ONE weekend (48 hours) you can disregard the hr/week thing as it does not apply. Those calculations are for a weekend use. Then I want to add a buffer on that of 25-30% just to be safe...

Does that explain my usage?

Cariboocoot

Re: first post - help with connecting panel and good build thread

minisolar wrote: »

No DC at all. Only AC. I have already calculated my power needs. I will only use this cabin from Friday afternoon until Sunday afternoon - once every other weekend. So 48 hours a weekend every other weekend....

I am attaching an image from the excel sheet i made that calculates the loads. So this is how much power I will need/use in ONE weekend (48 hours) you can disregard the hr/week thing as it does not apply. Those calculations are for a weekend use. Then I want to add a buffer on that of 25-30% just to be safe...

Does that explain my usage?

The attachment didn't show. Not that I can read Excel spreadsheets on this netbook.

I have to go for the day and do unpleasant things in the real world. But I shall return.

minisolar

Re: first post - help with connecting panel and good build thread

Attachment not found.

Maybe now the image works?

Coach Dad

Re: first post - help with connecting panel and good build thread

Hi minisolar
I don't believe that your refrigerator power usage is correct. You should look at that one again.
Is this wiring diagram what you are looking for?Attachment not found.


As you can see... I have a standard electric panel in the cabin while my Solar equipment is in the shed. I ran the inverter output underground from the shed to the cabin.
The Magnum inverter has a built in transfer switch and a built in battery charger. So when I start the generator, the inverter switches from battery power to generator power and it starts charging the batteries from the generator. Hope this helps.

minisolar

Re: first post - help with connecting panel and good build thread

The fridge will be a chest fridge conversion. 3.5cu. From what I read that is the watt pull but I won't know until I will have it. That is why I am planning with a 30% buffer. Also, I will shot the fridge off every-time before I leave.

I need help with understanding how to technically build the panel for the inverter/charger/generator. I just want to have my father in law do it for me so I can then begin buying solar parts and hook it up.

If you can show a photo and explain how is the panel wired from the panel - that will be a great help.

Cariboocoot

Re: first post - help with connecting panel and good build thread

I agree with Coach Dad about the 'frige; even a chest conversion is likely to draw more power than that. This is why actually measuring the loads with a Kill-A-Watt is so much better than trying to calculate usage based on the specifications given by manufacturers.

Another thing is that this shows Watt hours per week, or corrected by your early post weekend. You don't want to use that time frame. The old idea that you could run batteries down over a few days and then charge them up over a few days is not a good one. No matter whether the place is used only on weekends or not, you want to plan on a daily use/recharge cycle.

From my experience 2kW hours per day would not be unreasonable to expect to use. My own system uses just a bit more than that, and up to 3kW hours per day is quite normal for an off-grid cabin system. It is not hard to plan a system of that size: 2.4 kW hours / 24 Volts = 100 Amp hours used, meaning a minimum battery bank of 200 Amp hours. You can utilize the very inexpensive golf cart GC2's @ 220 Amp hours each, four of them in series to make 24 Volts. With a generator on hand "just in case" you should have no problems with maintaining power.

Coach Dad also mentioned the Magnum's built-in transfer switch and charger. Several other inverter of the "high end" variety such as Outback and Xantrex have this. It makes wiring very simple. When the generator feeds power to AC IN the inverter-charger switches to charging batteries and the loads on AC OUT are connected to the generator.

Basic formula for calculating array size: 10% of battery capacity for peak charge rate (22 Amps in this case). Multiply by either system Voltage and then apply panel & charge controller derating factor (22 * 24 / 0.77 = 686 Watt array) for an MPPT controller or simply multiple by default panel Vmp for PWM controller (22 * 35 = 770 Watt array). There is likely an advantage to having an MPPT type controller on a system this size, if for no other reason than the flexibility in array design it allows (you can use less expensive-per-watt 'GT' panels for one thing). By the way you won't get an array of exactly 686 Watts so you need to find a panel configuration that meets that minimum; more is better. The charge controller will have to handle at least 30 Amps. There are two new MPPT 30 Amp controllers: the Rogue 3048 which is now available and the MidNite "Kid" which should be available soon.

Once you have made the equipment choices and determined locations for it the wiring specifics can be planned.

minisolar

Re: first post - help with connecting panel and good build thread

"The old idea that you could run batteries down over a few days and then charge them up over a few days is not a good one"

but wouldn't the alternative - planning a system that can give me 2000kw a day (although I don't need such usage) be much more expensive?

1. You recommended 4 batteries. A quick google showed that they are 115-130$ each. Is that right? They are 6v each? http://www.solar-electric.com/cr225am6vode.html?gclid=CMLF-9zngrkCFcie4AodKUYAHg

2. I like the idea of having such a simple inverter that has everything built into it. If I do go for this kind of inverter - what other components to I need beside the panels & batteries?

3. Do I really need so much panels? seems like a ton.... They will have two weeks to fully charge the batteries.. Can I start with less and test it or there is no such thing?

4. Can you mention 3-4 models of inverters that will have those features and how much they should cost? I will try to see if I can buy them.

Thank you so much for your help btw... I am getting really excited!

Cariboocoot

Re: first post - help with connecting panel and good build thread

minisolar wrote: »

"The old idea that you could run batteries down over a few days and then charge them up over a few days is not a good one"

but wouldn't the alternative - planning a system that can give me 2000kw a day (although I don't need such usage) be much more expensive?

The reason you don't want to charge over days is that it increases the risk that the batteries will spend too much time at a low state of charge. The more that happens the faster sulphation takes hold and the shorter the battery life.

1. You recommended 4 batteries. A quick google showed that they are 115-130$ each. Is that right? They are 6v each? http://www.solar-electric.com/cr225am6vode.html?gclid=CMLF-9zngrkCFcie4AodKUYAHg

You can sometimes get "warehouse" brand GC2's from places like Sam's or Costco for <$100 each. Any way you slice it they tend to be the cheapest choice in terms of Watt hours per dollar.

2. I like the idea of having such a simple inverter that has everything built into it. If I do go for this kind of inverter - what other components to I need beside the panels & batteries?

Basic system components: batteries, inverter, solar charge controller, panels. The inverter can have an AC charger built in. Sometimes it is better (cheaper) to go with an external charger, but I've yet to see one that has proper charging for RE use - they tend to be not programmable so you can't make any adjustments.

Minor components will include mounting hardware for everything, correct size & length wiring to connect thing, possibly a combiner box for multiple panels, and of course fuses or circuit breakers for each section as needed. In addition you could have a battery monitor, but they aren't essential with flooded cell batteries; a hydrometer is cheaper and more accurate at measuring SOC.

3. Do I really need so much panels? seems like a ton.... They will have two weeks to fully charge the batteries.. Can I start with less and test it or there is no such thing?

In your case if the 2kW hours really is over two days (vital to double check those consumption numbers) you could reduce the peak charge current to 5% and halve the array size. Then you have to ask the question "what happens if they don't get charged?" It's nice to have a generator on hand; you could give the batteries a quick bulk charge before you leave and let the panels handle the rest.

4. Can you mention 3-4 models of inverters that will have those features and how much they should cost? I will try to see if I can buy them.

Our forum host's off-grid inverter section: http://www.solar-electric.com/inverters.html
For inverter-chargers Outback or Magnum would be the best choices here. Once you see the prices on those you may decide to go with a simpler, less expensive inverter only like the Samlex units and a stand-alone battery charger. It's a fussier install, but hundreds less money.

Thank you so much for your help btw... I am getting really excited!

Don't worry; you'll "calm down" when you start adding up the cost. Get depressed even.

minisolar

Re: first post - help with connecting panel and good build thread

I do not mind adding some buffer to that 2000watt just to be safe. I think 2500W should be more than enough.

About what you wrote with the inverters:

First, you said "but I've yet to see one that has proper charging" - you mean that you haven't seen an external charger that has proper charging abilities or inverter with charge that has proper charging abilities.
Second - what does RE stand for?

Halve the array size??! I like the sound of that (from the cost savings perspective of course). Then I can go with 343 watts of panels? that is great. I do have a generator that could will come in handy if my panels don't work.

How about panels.... there are different kinds out there , right? Which ones should I go for?

westend

Re: first post - help with connecting panel and good build thread

Mini,
A couple of links for you:
Solar use spreadsheet calculator

Golden Rules of Solar

These are from an RV perspective and some of the information is dated due to technological gains or pricing but may help for your off-grid system. Your useage is going to rule the entire system in an off-grid application. You want to nail it and then, like you've already done, allow some fudge factor. Additionally, when you have everything up and going, you may find additional electrical conveniences come to mind. Allow for some growth, I guess.

The power connections to your new AC load center are going to be defined by the type of inverter and the use/non use of a transfer switch. You may also find that a subpanel eases the installation. Jack Meyer outlines most of that in the "Golden rules" link, above.

Good luck with the installation!

Cariboocoot

Re: first post - help with connecting panel and good build thread

minisolar wrote: »

I do not mind adding some buffer to that 2000watt just to be safe. I think 2500W should be more than enough.

About what you wrote with the inverters:

First, you said "but I've yet to see one that has proper charging" - you mean that you haven't seen an external charger that has proper charging abilities or inverter with charge that has proper charging abilities.

External chargers tend to have fixed charging profiles with no ability to program the right Voltage set points and/or current levels for a given set of batteries; you take what they give.

The built-in chargers found in inverters like Outback, Magnum, or Xantrex have the programming function so that you can achieve the best profile for Bulk/Absorb/Float for your particular batteries.

Second - what does RE stand for?

Renewable Energy; the practice of generating power from PV or turbines and storing it up in batteries for use as needed.

Halve the array size??! I like the sound of that (from the cost savings perspective of course). Then I can go with 343 watts of panels? that is great. I do have a generator that could will come in handy if my panels don't work.

Yes, you can get away with a minimum 5% peak charge current if there are no loads running while charging. This can be useful for "walk away" systems. It will not work with all battery types, however.

How about panels.... there are different kinds out there , right? Which ones should I go for?

There are indeed different types. What you should go for is what can meet your power requirements without breaking the budget. You'll hear a lot of promo about how much "better" monocrystaline panels are. It isn't true; they're more efficient and more costly. That doesn't make them "better". But they may be the best choice for an RV application where space is limited and you need to get the most Watts per area. Amorphous panels will be promoted as being very inexpensive per Watt. But they also are very inefficient and require much more space to produce the same power.

Often the least expensive are "GT" panels, meant for grid-tie systems. They will have "odd" Voltage for battery-based system and so must be used with MPPT type charge controllers to maximize efficiency.

As far as name brands are concerned there's hardly a gnat's hair's difference in quality between them.

erne

Re: first post - help with connecting panel and good build thread

One thing to consider on the refrigerator is most conversions use 200 w/h per day and use about double that to be brought to temperature every time you arrive. You might want to consider bringing ice to lower the startup usage.

minisolar

Re: first post - help with connecting panel and good build thread

That's a great tip. Thank you!

Where have you seen posts about this?

minisolar

Re: first post - help with connecting panel and good build thread

Then this is great news for me - I was inclined to go with the built in charger type inverter anyway... Now even more.

If I go with this, higher end type inverter, that has a switch box and charger built in, what type of wiring do I need to do for my panel?

Also, then if I do use this type of inverter I will also need batteries and panels. Then the only other thing I need is those devices that monitor the system?

I saw a youtube video with a guy that has the Trimetric 2020... It gave him so much info. Seems like a great thing to have. So I am open to getting any other type of device but I would need a monitoring component right?

Also, I saw that I need to equalize the batteries or something... Is that with all batteries? Are the ones we discussed need to have that?

BB.

Re: first post - help with connecting panel and good build thread

The current Trimetrics are here:

www.solar-electric.com/tr20mosy.html

Battery monitors (Victron is another good brand) are really nice--However, they do have their limitations. If you have flooded cell batteries, you should still check specific gravity once in a while to make sure the battery monitor and battery itself are still in sync.

And you should read all you can about batteries... There are many ways of killing them:

http://www.windsun.com/Batteries/Battery_FAQ.htm
http://www.batteryfaq.org/
http://batteryuniversity.com/

And you need to read the manual for your batteries... In theory, sealed batteries should not be equalized and flooded cell batteries should only be equalized when the cells are "out of balance" (for example, specific gravity between the high and low cells are 0.015-0.030 or higher differences). Some vendors will recommend "light" equalization every 1-2 months or so... A good battery mfg. will put their requirements in the manual--And many vendors do not.

-Bill

vtmaps

Re: first post - help with connecting panel and good build thread

Cariboocoot wrote: »

External chargers tend to have fixed charging profiles with no ability to program the right Voltage set points and/or current levels for a given set of batteries; you take what they give.

The built-in chargers found in inverters like Outback, Magnum, or Xantrex have the programming function so that you can achieve the best profile for Bulk/Absorb/Float for your particular batteries.

Cariboocoot has told you the truth, but not the whole truth.

Most lead acid deep cycle batteries and most battery chargers for them are NOT used in RE applications. RE is a niche market. Most chargers use (and most battery manufacturers recommend) a charging profile that is very different from the "bulk-absorb-float" charge profiles used by RE manufacturers like Outback, Magnum, or Xantrex. The RE chargers can NOT be programmed to give the charging profiles that most battery manufacturers recommend. Furthermore, to add to the confusion, the battery manufacturers use the terms "bulk" and "absorb" differently than the RE manufacturers do. You can ruin your batteries by setting your RE absorb voltage to what the battery manufacturer recommends for absorb.

I'm not saying that the RE style "bulk-absorb-float" is a bad thing... its just something else to learn about :-)

--vtMaps

minisolar

Re: first post - help with connecting panel and good build thread

Ok. I read about batteries. Still not sure exactly which ones I should get. I now know why the 50% dod was mentioned...

Then I need to follow the three stage charge?

Any good page on inverters?

minisolar

Re: first post - help with connecting panel and good build thread

Found the inverters page...

Questions -

1. I think my surge power will be quite small... Only the conversion fridge and maybe my RV pump and heater? My cistern pump (will only work for a few minutes once I get to the cabin and fill up my indoor 18 gallon tank) is this one: http://www.amazon.com/gp/product/B000X05G1A/ref=ox_sc_sfl_title_3?ie=UTF8&psc=1&smid=ATVPDKIKX0DER
Then should I go for the (less expensive) "high speed electronic switching type" inveter? Or maybe they don't come in that charger/inverter/switch box type?

2. I also intend on using my tools if possible. A miter saw, circular saw, compressor and so on. But if the cost of getting a stronger inverter is great - I don't mind just running the tools of my generator which is a sunk cost. See my point/question?

3. I do have a fridge and even a dimmer that will run LED bulbs. Does this mean that I should get a sine wave type or can I get away with modified? Also, if it improves the live of my electronics, as I intend on plugging my laptop and such, then I don't mind going for the sine. Obviously - it depends on how much it is/.

4. Solar panels - it said in the info that you should match them. Does that mean that if I shouldn't mix different types of solar panels together? A friend has a few panels and want to give them to me and I thought I could use them and just add more panels as they are only 100watt....

BB.

Re: first post - help with connecting panel and good build thread

minisolar wrote: »

1. I think my surge power will be quite small... Only the conversion fridge and maybe my RV pump and heater? My cistern pump (will only work for a few minutes once I get to the cabin and fill up my indoor 18 gallon tank) is this one: http://www.amazon.com/gp/product/B000X05G1A/ref=ox_sc_sfl_title_3?ie=UTF8&psc=1&smid=ATVPDKIKX0DER
Then should I go for the (less expensive) "high speed electronic switching type" inverter? Or maybe they don't come in that charger/inverter/switch box type?

It is hard to say--Starting surges on such pumps can be upwards of 5x running current. The pump is "cheap enough" that you can get an inverter that meets the rest of your (lower power) needs and try it... If it does not work, you can choose to get a larger (cheaper) MSW inverter and run that load (plus your saws, compressors, etc.) sort of OK (TSW inverters are much better for induction motors like this pump and some electronic loads/power supplies/AC battery chargers, etc.)--But for hand tools with Universal (brushed) motors, MSW is OK too.

But--for any large inverter/heavy loads--You need a battery bank sized to support those loads. If these loads are not often (weekend work around the home, couple week project at a time, etc.)--A genset is usually going to be more cost effective (just dump in fuel when needed) vs a possibly over-sized battery bank+Inverter+solar array that is rarely used to capacity.

Or you can try a "nicer" AC or DC pump that will cost more but be more compatible with a lower power off grid lifestyle.

2. I also intend on using my tools if possible. A miter saw, circular saw, compressor and so on. But if the cost of getting a stronger inverter is great - I don't mind just running the tools of my generator which is a sunk cost. See my point/question?

Yep... Some people go with two inverters... A nice smaller TSW for "critical loads" and a large MSW inverter when needed for running a pump/shop tools/etc. However, that pushes up battery bank capacity and solar array capacity--All additional costs and maintenance issues.

You might think along the lines of two generators... A Honda eu2000i class (~1,600 watt) genset for most of your smaller power needs (and possibly recharging battery bank in bad weather--if the bank is not too large)--And a second 3.5-5 kW "noise maker" for the compressor, table saw, etc... And as a backup for the small genset and solar power (backup for the backup--always a good idea if you are in a remote area).

3. I do have a fridge and even a dimmer that will run LED bulbs. Does this mean that I should get a sine wave type or can I get away with modified? Also, if it improves the live of my electronics, as I intend on plugging my laptop and such, then I don't mind going for the sine. Obviously - it depends on how much it is/.

A fridge would be good to have a TSW inverter (induction motors can pull ~20% more power from MSW and waste it as heat). And for electronics--Some work very well on MSW supplies, and others will only last days or minutes on MSW--I can go into my theory on why and how to tell which will work where--But smaller AC power supplies and wall wart transformers tend to run on hot on MSW power.

And with refrigerators, you now need to study how they work too... Most have pretty nasty starting surge and require a 1,200 to 1,500 watt minimum inverter to run reliably and share with a few other appliances/lights in the home.

And if you get a frost free type refrigerator, you need 24x7 AC power for them because, generally, the new models have electronic defrost timers which reset back to zero if the AC power goes away and start a new defrost cycle.

Simple frost full fridge and freezers can usually be setup to turn on the AC inverter when they need power... A good sized AC inverter will use ~10-20+ watts just being "on" -- So running an inverter 24 hours per day can be almost 1/2 the load of the refrigerator itself.

4. Solar panels - it said in the info that you should match them. Does that mean that if I shouldn't mix different types of solar panels together? A friend has a few panels and want to give them to me and I thought I could use them and just add more panels as they are only 100watt....

It is the Vmp/Imp ratings of the panels and what you are connecting them too... Can you give us the details of your current system (present array numbers, charge controller, battery bank voltage) and the Vmp/Imp + # of panels you can get from your neighbor and we can discuss the details.

More or less, you want to match parallel panel connections Vmp to withing 10% of the other panels, or if in series, match Imp of panels to within 10% or better.

It sometimes just requires a second MPPT charge controller for the new panels to "play" well with your existing system--Just additional costs for the new MPPT solar charge controller (not cheap).

-Bill