How do I 500W Grid Tie Inverter wire it up for battery backup?

bob5731

I have 500W Micro Grid Tie Inverter for Solar Home System MPPT Function PURE SINE WAVE.
How do I wire it up for battery backup?
So if I lose my power the batters kick in then?
https://www.youtube.com/watch?v=x5BAFeOqt3U
I have the harborfreight 45 Watt Solar Panel Kit and wire going to a harborfreight 500 Watt Solar Charge Controller.
http://www.ebay.com/itm/500W-Micro-G...:X:AAQ:US:1123

westbranch

please do a search for the proponent of that system, https://www.youtube.com/watch?v=x5BAFeOqt3U ,on this forum, and then decide if you wish to give him your hard earned cash...

froggersix

you can't connect batteries to a grid tie inverter only to an inverter meant to run from batteries.

bob5731

[h=1]GRID TIE INVERTER SOLAR panel POWER EASY Electricity Savings[/h]

https://www.youtube.com/watch?v=hANi5NbcY5g

BB.

Bob,

That MW&S system--Basically it is an off grid system (the AIMS inverter) that runs from DC Battery bank to the AC off grid loads. Note the warnings:

Because grid power is not 100% reliable, we are unable to allow the connection of wind turbines directly to this control board. However you may use an additional charge controller of suitable size and with its own diversion load to connect wind turbines to the same battery bank. This will help fill the batteries even faster and can provide valuable power at night. Even though the grid tie inverter is connected and prewired to the control board, it is not UL1741 listed. A common question we're asked is "Can I connect the grid tie inverter output to the regular battery inverter outlet/receptacle or visa versa," the answer is NO as this would most likely cause failure of the system in part or in full (i.e. irreparable damage). This controller board is simple to install, but, if in doubt, hire an electrician to help you.

Then there is MW&S's dump controller that is connected to a GT Inverter (120 VAC @ 500 Watt for that system)... When the battery is full, the dump controller turns on and feeds power back to the AC Grid (not connected to the AIMS/Off Grid Loads that I can see).

If you wanted to have a "protected AC Sub Panel" that would feed your AC loads with Grid Power OR Battery Backed Up Inverter power--You would need to do something else. Basically you would need a Transfer Switch, or an Off Grid Inverter with an internal AC transfer switch, or a "hybrid" AC inverter that can do both GT and OG mode.

Note that while the GT inverter used here does function it is "Not UL 1741 approved device."

The MW&S video and the video on GT inverter in the other Youtube video--They are not UL 1741 Listed devices and not legal to connect to your home's AC wiring. If you want to use either system, you do this at your own risk and liability (i.e., your insurance may not pay if there is fire--related or not to your installation, and if there is injury/damage to other's property, you have have serious legal consequences).

I am more than happy to discuss the details of the systems... And if they "can work" or not, possible weaknesses in the systems, etc.

However, do not take my discussion as a "how to install" set of instructions. There is no "legal" way to connect this type of GT system to a home/utility grid in North America in most jurisdictions (there are some/many rural locations that do have inspection requirements).

Will it work as shown in the video--Yeah. We have had a few posters here that have tried other brands of non-UL compliant GT inverters and they tended to be unreliable and run hot. How will this one run--No idea.

-Bill

westbranch

These type of units are Illegal to plug into your outlets for a reason... If a fire is caused it will probably invalidate your insurance ... play it safe...

mike95490

bob5731 wrote: »

I have 500W Micro Grid Tie Inverter for Solar Home System MPPT Function PURE SINE WAVE.
How do I wire it up for battery backup?
So if I lose my power the batters kick in then?
https://www.youtube.com/watch?v=x5BAFeOqt3U
I have the harborfreight 45 Watt Solar Panel Kit and wire going to a harborfreight 500 Watt Solar Charge Controller.
http://www.ebay.com/itm/500W-Micro-G...:X:AAQ:US:1123

This inverter is not designed to work with batteries.

inetdog

mike95490 wrote: »

This inverter is not designed to work with batteries.

And it is also designed not to operate without the grid power being present (as required by the UL listing that it does not have).

bob5731

Then what do I need add to make it work it battery backup for win the power go out os the batters kick?

inetdog

bob5731 wrote: »

Then what do I need add to make it work it battery backup for win the power go out os the batters kick?

You need to buy an off-grid battery powered inverter. And batteries. And a Charge Controller.
In other words, you need to build an off-grid system from scratch, not using any of the parts from the grid tie system except the panels.

BB.

How large of system do you need? What do you want to power?

In general, there are not a lot of smaller hybrid inverters (grid tie + off grid capable).... If you want a smaller off grid system, generally you just use an off grid inverter + battery bank + solar panels + solar charge controller + (your option) a backup AC charge controller + genset. (or an off grid inverter-charger unit).

True hybrid inverters backfeeding the grid are generally larger (3kWatt inverter or larger). If nothing else, the costs of permits, installation, inspections, power company approval, possibly a new utility meter, etc. generally mean that smaller GT type systems are just not worth the trouble.

Does this mean that you will "lose money" because unused power from the solar panels has nowhere to go--Yep, it does.

-Bill

bob5731

a/c heater.

bob5731

looking for something like the GOAL ZERO YETI 400 SOLAR GENERATOR.

Photowhit

bob5731 wrote: »

a/c heater.

I have roughly a $10,000 off grid system, ...and I heat with wood...

My minimal system to run a window air for 4-5 hours a day on thermostat, in a well insulated room, could be put together for $2500-3000....

It would include a 1000-1200 watt array, 4 golf cart batteries, a charge controller (PWM 60 amp) and a 1500-2000watt inverter, wiring, fusing, combiner box, framing and a bit of knowledge... This can reliably allow for 4-5 hours of a/c on thermostat, in the well insulated room, on days when the sun shines...

Photowhit

bob5731 wrote: »

looking for something like the GOAL ZERO YETI 400 SOLAR GENERATOR.

This does not fit your goals, would not run a heater or a/c for any appreciable time.

bob5731

then what do I need to add.
hare is what I have http://​https://www.facebook.com/OffTheGridSolarEnergy

Photowhit

https://www.facebook.com/OffTheGridSolarEnergy

I don't see any system information that is useful at this face book page.

If you would like to post the equipment that you have for off grid use, or a coherent idea of how much energy/watt hours your load will be there are many here who can help you.

From your posting here and the facebook page it looks like you're taking the shotgun approach, this is likely to be expensive and a waste of time.

bob5731

3000 Watt Continuous/6000 Watt Peak Power Inverter
http://www.harborfreight.com/3000-watt-continuous6000-watt-…
Tolerance +\~ 3%
Open circuit 21.99
Voltage 17.53
Max current 6.28 amp

3 45 Watt Solar Panel Kit

[FONT=helvetica, arial, sans-serif]battery[/FONT]
[FONT=helvetica, arial, sans-serif]12v 100amp hr[/FONT]
[FONT=helvetica, arial, sans-serif]12v 86amp ah[/FONT]
[FONT=helvetica, arial, sans-serif]12v 86amp ah[/FONT]
[FONT=helvetica, arial, sans-serif]12v 97amp ah[/FONT]
[FONT=helvetica, arial, sans-serif]have 4 12v SRM-24 [/FONT]http://www.interstatebatteries.com/p...798-2147384903
[FONT=helvetica, arial, sans-serif]but using one of the 4 [/FONT]12v SRM-24

My Portable Air Conditioners are LG LP0711WNR and Amcor kf9000e

BB.

Bob--The system you have listed will not really meet any of your needs. Way to little of solar panels. Way too large of AC inverter, and the 12 volt battery bank is way too large for the solar array and way too small for the AC inverter (to run at rated load).

Plus, 3,000 Watt AC inverters @ 12 volts usually are not going to work well and be expensive to wire. The current needed to run one would be:

• 3,000 Watts * 1/0.85 inverter eff * 1/10.5 volts cutoff = 336 Amps at 3kWatt AC load (huge copper cables)

3x 45 Watt solar arrays would supply on a sunny day around (and the Harbor Freight 45 Watt panels don't even usually output anywhere near their 45 watt rating, and usually do not last very long):

• 3 * 45 watt array * 0.77 panel+controller derating * 5 hours of sun per day = 520 Watt*Hours of charging current on a reasonably sunny day
• 520 Watt*Hours per day of energy * 1/(3,000 watt load * 1/0.85 inverter eff) = 0.147 hours of energy per day = 8.9 minutes of 3,000 Watt load per day

And the DC battery bank if it ~500 AH @ 12 volts would support around a 1,250 Watt Maximum AC inverter using (using the 400 AH per 1,000 Watts of inverter capacity on a flooded cell lead acid battery bank).

Plus the batteries (at least the Interstate batteries) are not true deep cycle batteries, but Marine batteries. If you pull them down to 50% state of charge, they usually do not last very long (months to year, not 3-5 years for a typical deep cycle golf cart battery).

The mix of hardware (as I understand it) does not play well together at all.

Of grid solar power is not cheap--And if you are looking for seasonal/weekend cabin power usage--A generator + fuel is usually a cost effective alternative to solar panels+batteries+electronics--Unless you are going to be off grid for 9+ months a year. And if you you still want solar power for running Heat Pumps--The system design needs to start over from scratch.

For example, say you need 1,000 Watts * 12 hours per day for your two AC systems total (assuming very well insulated cabin and you run the two heat pumps at ~500 Watts each--low power).. A typical system may look like:

• 1,000 Watts * 12 hours per day * 1/0.85 AC inverter eff * 2 days of storage * 1/0.50 max discharge * 1/48 volt battery bank = 1,176 AH @ 48 volt battery bank (about 8x larger than yours)
• 1,176 AH battery bank * 58 volts charging * 1/0.77 panel+controller deratings * 0.10 rate of charge = 8,858 Watt solar array nominal (based on battery bank size)
• 1,000 Watts * 12 hours per day * 1/0.52 end to end system eff for off grid solar * 1/4 hours of sun per day = 5,769 Watt solar array (based on minimum of 4 hours of sun per day)

Without knowing anything more about your loads, the above is my first guess (you would throw in a 4 kWatt @ 48 volts off grid AC inverter too). Plus charge controller, plus backup ~10 kWatt AC genset (if you need one).

As we say--You start with your loads (amps, watts, hours per day), look at conservation (most efficient loads you can get, use insulation, LED lighting, etc. to get your heating/cooling loads a low as possible). Then start the design for you solar power system. Any other way, is most likely going to be costly and frustrating for you.

-Bill

bob5731

Jest got a watt's up meter. How to I wire it up to read batteries and the solar panels?

BB.

Do you have a link to the Watt meter?

-Bill

bob5731

Hear is the Watt meter
http://www.ebay.com/itm/371141580880?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

inetdog

bob5731 wrote: »

Jest got a watt's up meter. How to I wire it up to read batteries and the solar panels?

The watt meter you linked to is a DC meter with two input leads and two output leads. Potentially a lot of voltage drop there, and you are limited by the wire size they provide. A more expensive and useful meter would use a shunt to get the current and would need only three small wire (no current) to connect to the shunt and the + terminal.
You can choose the measure the current into and out of your battery (probably the most useful) or the current going to your inverter to feed loads (could be interesting) or the current coming out of your panels to the CC.
You have to choose one of those. And if you measure current between the battery and the inverter, that meter cannot handle the current involved.
3.3kW divided by 12V = 275A. Limit is 150A.
And if you choose to measure the panel current, make sure the voltage is not more than the 60V limit of the meter.
It looks nice but has some serious limitations that might make it useless to you regardless of the low price.

Johann

bob5731 wrote: »

a/c heater.

This may be a better solution if you after heating and cooling and want to suppliment the grid power use. http://www.hotspotenergy.com/solar-air-conditioner/
. If I remember right it uses solar panels to power the unit and then uses grid if the sun is not shining.

Looks like those goal zero's have only 400 watt hours.

inetdog

Johann wrote: »

This may be a better solution if you after heating and cooling and want to suppliment the grid power use. http://www.hotspotenergy.com/solar-air-conditioner/
. If I remember right it uses solar panels to power the unit and then uses grid if the sun is not shining.

Looks like those goal zero's have only 400 watt hours.

An interesting idea, and to the extent that you use the AC when the sun is shining (near solar noon) it makes theoretical sense. No experience with how well they really work.

This in nothing that a grid tie inverter and AC powered inverter drive mini-split would not do better though.

bob5731

I'm looking to add solar panels to my setup. What low cost panels would work?

BB.

Sizing your off grid power system--That is the $20,000 question.

We really need to know/understand your loads & electrical needs. If you already have AC Mains, then your utility is going to be your cheapest source of power--Unless you want to do Grid Tied Solar (solar panels -> GT inverter -> Main House Panel).... In some cases, GT Solar power can actually save you money (but it does depend on where you live, your utility's rate plans, etc.).

Off grid solar power--Is pretty much always going to cost you more money than utility power... Typically around $1.00 to $2.00+ per kWH--Although a few people here have gotten down into the $0.50 per kWH (shopping for good prices, designing a system that pretty much exactly meets their power needs, etc.).

If you are looking to save money, focus on energy conservation first. Start with insulation, double pane windows, more insulation, LED lamps, Energy Star Appliances, turning stuff off when not in use, etc.

If you are looking for backup AC power (2 weeks or less)--Look at a genset and stored fuel (or natural gas if available). Generators can be cost competitive with off grid solar power--But, again, you really should design your generator system for your power needs. If your loads are small, then an 8kWatt genset that may use $1-$2 per hour in fuel may be way way more than you need if a 1.6kWatt genset will keep you in lights and run your refrigerator for a few weeks (run the genset for 1/2 the day, on a $5 dollars of fuel per day).

If you are looking for 1-2+ months per year of backup power, a smaller solar power system + battery bank + off grid AC inverter may be helpful. But sizing the system to run all of your AC loads (including air conditioning, etc.)--Then it may simply be too expensive to be worth it for emergency backup power (see genset instead). An off grid system that can run even a smaller single AC system (one room), will probably cost you many tens of thousands of dollars. Plus you need to replace the batteries every 5-8 years or so, new AC inverter+charge controller/electronics every 10+ years, etc.

-Bill