Solar system review

[Sunking]

There is only one real good battery monitor you can buy, a temperature compensated hydrometer like this one. Once you get a really good lab quality hydrometer you can then exercise your battery and with a good volt meter make a decent SOC graph with this procedure. It is the only way to do it accurately.

[Mike90250]

.......
I have heard many diffrent oppinions about how to size the inverter as well. If my draw is say a maximum of 3Kw, then some say I should have a minimum of a 6,000watt inverter. Others say a 4000 would work fine. I think I will end up with a 5000, just so I can expand a bit if I need to, but I am not sure why I would need a 6000watt. Any idea's?

Add up the loads you expect to have on at one time. 300 + 200 + 20 + ??????
That gives your baseline. Are any of those loads a motor ? Any large loads expected to come on, while baseline loads are on ? If your inverter cannot handle the starting surge of a fridge, while the lights are on at night, the lights go off ! The inverter will often try to reset it'self and blink the lights a couple more times, while the fridge is also trying to start.
I'm running a farmhouse, with a 1/2 hp well pump, and my inverter is rated for 200% overload for 10 seconds (12 Kw) It's a 6Kw inverter on 48V, so far has been fine running the pumps and the shop tools.

You need to see what the inverter overload specs are. Morningstar has a 300w inverter ,with overload of 600w for 10 min. It generally is not enough to start a fridge though. They are all different.

[mikejh]

Ok, it sounds like a pure sine is about manditory for me then, although like you said, I will check into it a bit more.

I have heard many diffrent oppinions about how to size the inverter as well. If my draw is say a maximum of 3Kw, then some say I should have a minimum of a 6,000watt inverter. Others say a 4000 would work fine. I think I will end up with a 5000, just so I can expand a bit if I need to, but I am not sure why I would need a 6000watt. Any idea's?

[Mike90250]

...I am also looking for a good battery charge indicator.....

Me too! They don't exist.

What do exist are "battery totalizers". They have a shunt, that measures all the current in and out of a battery, and they assume that it need 120% return for power taken out.
They come pretty close, to giving a good acounting of the State of Charge of a bank, but you still periodically have to check each battery, and decide if you need an EQ charge.
Sold as battery meters or whatever snake oil phrase is working that month. The tip-off is it needs a shunt, and look for one that measures both in and out.

[Mike90250]

inverters mod vs pure
Everything is fine on Pure sine

heating type appliances don't care. (toasters, blow dryers, incandesant lights)

motors: small brushed motors don't care, but un-brushed motors will consume 20% more power, and some burn up, (fridge compressors, pumps, ceiling fans) and some are fine. But wattage consumed is 20% more. (and battery life is reduced)

electronics: some buzz, some are fine, some fail in minutes.

CFL lamps: some flicker, some are fine, some buzz

Transformers : like motors, they will consume 20% more power and run hot. Some fail, some don't. (heavy, wall wart power supplies)

Get some more opinions - not just mine

[mikejh]

How important is it to get a pure sine inverter? Since I am not running computers or small electrical devices, would a modified sine wave be fine? I am just asking because it is another $600 to get a pure sine vs. the modified sine. This is the one I have been looking at:

http://www.theinverterstore.com/the-inverter-store-product.php?model=pwrinv500012w

The same one, only pure sine is $1,000.

I am also looking for a good battery charge indicator. There are so many of them and the prices are so drastically diffrent, it is hard to know which one to get. Just though I'd ask, because i'm sure somone has done all the reasearch already.

[mikejh]

Ok, that sounds great. I could also run two panels off of one controller and two off of another, having a compleatly redundant system. I know this probably sounds crazy, but I am a pilot and am used to making everything redundant... Wire isn't an issue, because I have a few houndred feet of it laying around.

[Mike90250]

Hooking up parallel controllers is easy, and if they don't have inputs for the battery temp, there is nothing further to do to them.

+ to +, - to -

With MPPT controllers, you want to only have matched panels on each, don't mix flavors or sun angles on one controller, it drives them nuts and screws them up.

[mikejh]

Xantrex has a 600VDC charge controller, it may be 80A.
Midnight Classic 150 is good for 96 amps.

At some point, (now?) you need to consider going to 2 charge controllers. It's OK to parallel charge controllers, and if they are the same brands, some can share the Batt Temp Sensor, and sync their charge stages.

So I could just get another 50A controller and run them in parallels? That would be awesome! Is there a diagram showing how to wire them up? Also, I don't think that the Instapark controllers can have a batt temp sensor. Do I need to get an external one?

http://www.amazon.com/Instapark%C2%AE-MPPT-50-Solar-Charge-Controller/dp/B004XCOCC8/ref=sr_1_13?ie=UTF8&qid=1312301291&sr=8-13

[Mike90250]

Being that I have to add more panels, I am returning the 50A charge controller, and am going to have to get a bigger one. I am not finding many MPPT charge controllers over 60A, other than the Outback. Do you guys have any reccomendations for bigger charge controllers? Thanks.

Xantrex has a 600VDC charge controller, it may be 80A.
Midnight Classic 150 is good for 96 amps.

At some point, (now?) you need to consider going to 2 charge controllers. It's OK to parallel charge controllers, and if they are the same brands, some can share the Batt Temp Sensor, and sync their charge stages.

[mikejh]

Being that I have to add more panels, I am returning the 50A charge controller, and am going to have to get a bigger one. I am not finding many MPPT charge controllers over 60A, other than the Outback. Do you guys have any reccomendations for bigger charge controllers? Thanks.

[mikejh]

PM sent. I'm having a hard time figuring out how a 5kw system is anywhere under 6/8K.

[john12]

PV solar system

For the solar power system,the PV grid tie one is a better choice compared with the off grid one.
PV grid tie power system can supply eletricity more stable
As for 5 people family,a 5 kw on grid system is enough,and it just cost 3k, and local goverment will offer allowance for the solar product.
You can tontact me ,and my e-mail:

moderator note - it is not good to place your email on any forum plus advertising is not allowed.

Also - your 3000$ for a 5 kW system is totally wrong.

Russ

[mikejh]

That clearifies things a bit. The only thing I don't understand now is how it can say both 400watts and 2 kilo watts.

Missing information = hours put in each day.

[Sunking]

No the screen is not leaving out a character.

Watt = Voltage x current, so current has something to with watts, but only half of the equation. 1000 watts = 100 Volts x 10 Amps = 10 Volt x 100 Amps = 50 Volts x 10 Amps

Watt Hours is a terrible complex formula that takes a 8 year college education to understand and apply.
Watt Hours = Watts x Hours..

Watts is just an instantaneous measurement of power at a moment in time like a snapshot of a picture. Watt Hours is a measurement of power over a period of time. For example how much power does a 100 watt light use in 10 hours? 100 watts x 10 hours = 1000 watt hours = 1 Kwh.

Electric power is all about numbers and formulas. Think of it like money. If you earn $10/hour, how much money do you make in a day, week, or year? There is no answer to the question because there is missing information. What is information is missing?