Cheap inverter

read here, not good  http://forum.solar-electric.com/discussion/comment/305302#Comment_305302

There is no such thing as a cheap inverter. Its a contradiction in terms. Those that try, inevitably find that out.
Another inverter myths, bigger is better, "ill only run it at 1500W". Doesnt account for the tare, such inverters can often draw 80W doing nothing. Ouch.. Doesnt account for that they probably designed the 3000W unit as a 2000W unit and added a bigger fan, and some bodges.

Stick around, do some reading here. Your system will be the better for it.

junglejoe39 said:

Several people have told me 24v system would be better more efficient ?

People are people they'll tell you anything, unless you ask for information, like "What kind of system do you have?"

So let me tell you about your system, that I know nothing about, other than you will stay under 1500watts peak.

Since you can mount the inverter 2 feet from your battery bank, and you have minimal needs of half a KW a day, but you like your popcorn in your fancy microwave. You could purchase a 2000 watt inverter from Xantrex for @$350. A Samlex 24 volt 2000 watt would run nearly 2 times as much and is about as low a priced inverter that I could recommend.

12 volt inverters aren't simple to use if you have a minimal battery bank. but a short connection with thick wire can solve most of the problems.

People do always seem to want a big inverter, I've lived with in the capacity of a 1800 watt inverter (yes, at 24 volts) for the last 10 years or so... Including running a hot water heater, toaster oven, microwave, clothes washer...

So some advice, figure out what you want to do. even 1500 watts peak tells us next to nothing. There is a huge bank of experience here that can help you design a system to fit your needs.

I haven't seen the 1800 watt version going for less than $6-700 too often, though I have purchased a 5 year old unused one for @$400 shipped off eBay several years ago. I don't mind suggesting looking for a used inverter. You might also search for Iris Quiet Power inverter. The 1800 watt version of Prosine is/was sold to the military under those specs. As usual be careful, you could get one full of sand from Iraq or one required to be replaced every so often out of an armory!

Not a recommendation, this one looks to be well used, but this is what the 'Quiet Power' version looks like;

http://www.ebay.com/itm/1800-Watt-24-Volt-Power-Inverter-M998-M1078-Hmmwv-/121885564882?hash=item1c60f21fd2:g:W-EAAOSwXshWs73Q

All Iris Quiet Power inverters will be 24 volt, for military vehicles. Prosine's will need to check specs! They come in 12-24 volt versions, 1000 and 1800watt versions in 120, 230 volt output versions. There are also 2000, 2500 and 3000 watt version that have chagrers built in, I have no experience with these.

I hate to say it, but looks like teh power co is onto you, and you best be careful. They have algorithims to detect odd usage patterns.

Budget is not really a reason to do anything that is illegal or dangerous.  So called plug in grid GTI inverters are not scantioned by any power company that i know of, and the quality of these devices is by defintion dodgy, because all inverters certified for grid coonection undergo extensive testing. An approved grid tie connection ensures the safety of line workers, neighbours,you and your home and family, as well as your home insurance.

So for anyone else contemplating doing this... its a bad idea. OK, so having said this, thats all im going to say on teh subject, what you do is your business.

A battery inverter is a whole other beast from a GTI. The battery is the lynch pin of the system. On a long term basis its the most expensive part of the system, and its this that unfortunately makes off grid challenging to compete with teh grid on a cost basis. If you think about it this way, whats the cost of batterys in terms of per kWh?

Take for example the following battery:
- 10kWh, with a rated cycle life of 2000 25% cycles.
- that works out to = $2000/(10kWh*0.25*2000)
- or $0.40/kWh

So right there its already more than the cost of grid service. So, tricky proposition. However there are ways to alter the maths, lots and lots of homework, and being in the right place at the right time, landing on say a used forklift battery, and just occasionally people have some success with ex government /telco cells.

> may even use my grid tie inverters off my battery bank to supplement the dryer at peak input times. Why I asked about the inverter and charger cables being together.

To answer your question about the inverter and charger, its a circuit right?, whatever the inverter cant get from other sources itll draw from the battery. Whether a GTI would work at battery voltage, that depends on the product, id say its pretty unlikely.

>Im not really looking for storage just as a buffer to supply as much of my homes consumption as possible and keep my batteries golden. After dark Ill go back to grid power. Im prob. headed into uncharted territory.

That there is a problem. A DC coupled charge controller and a battery based inverter both requires a battery, and one specifically sized as above. As said, the only battery that will work well for this application is a lithium pack. But they are expensive, so your stopped there as well. With some electronics and creativity you might be able to craft an AGM system that allows the solar to power the house during the day, without exceeding the max charge rate fo the bank. (Midnite recently announced that their classic charge controller is getting battery current limiting any day).  That protects your proposed small bank from high charge rates, but teh inverter still needs to be able to draw teh current it needs. The main difficulty is managing the sun. When the sun goes away you have to what hit the transfer switch to avoid teh (realtively big) inverter sagging the (relatively small) battery. Tricky, tricky.

junglejoe39 said:

... Last night I bought a Cotek 24v to 120v 1500w 3000w peak pure sine inverter. Says mounted never used 160$ + 20$ shipping. Battery bank will start with 2-35ah 12v in series and add 2 a month till I have enuf.

Sounds like a heck of a deal!

I didn't catch why you need the batteries inside? Bad neighborhood? Mine always live outside. This allows the use of flooded batteries, best bang for the buck in a small system would be golf cart batteries. 4 - 6volt from Sam's club or Costco around $100 a piece without exchange, $80 with(often will take car batteries) could even go with 3 - 8 volt, about the same price.

You asked about use when charging. It will use the power generated  by your array when available. So day time use is very productive. If we haven't lost you I'll go more indepth...

Im still being cheap and what I am looking to do is get as much use out of my solar with as little investment as possible.

A lot of people want to do that - but going that route is dangerous, and people have gotten burned (literally) by trying to 'go cheap.' There are some things you can't skimp on, like wiring, protection devices and safe inverters.

I may even use my grid tie inverters off my battery bank to supplement the dryer at peak input times.

Don't do that - cheapo Chinese GT inverters will be somewhat unpredictable with a stiff voltage source instead of the more limited source supplied by a PV panel that they are expecting.

Why I asked about the inverter and charger cables being together. Im not really looking for storage just as a buffer to supply as much of my homes consumption as possible and keep my batteries golden.

1) Topology changes on the cabling won't significantly change how much power goes to which source. That is set primarily by voltage sources and impedances within the devices.

2) In general I'd recommend two wires to your battery (one on each post) going to a distribution center. Put an overcurrent device (breaker or fuse) right at the + terminal of the battery. Rate the wire above the rating of the fuse; there are plenty of tables around to figure out what gauge you need for what current. Then fuse or protect each wire coming off the distribution bus per its wire rating.

3) For multiple batteries there are, again, several drawings around showing the best way to wire them. Here's a good explanation: http://rvroadtrip.us/library/12v_system.php

zoneblue you should know what you are talking about. There are companies right now selling solar with a grid tie as an appliance not regulated by the power co.

There sure are. And those companies are quite happy to take your money and deliver you a product you can't legally use.

there are several models of 1500W inverters that they make, which one did you get?