Home Inverter as Continous Load, 24 Hrs/365 Days

50W losses at no load is a bit of exagerated estimation but then at higher loads like 400-500W is acceptable value for a good quality inverter so all depends on how "erratic" your grid is and how expensive your sensitive to "erratic grid" devices are. 53 2E 4D 2E

Rather than guess why not measure the no-load current and voltage? I suspect that the results will vary wildly across the spectrum of manufacturers, design sophistication and age of device/batteries. Simple brute force inverters will consume more energy than modern microprocessor controlled systems.

The inverters I install draw 18 watts in standby and 6 watts in search mode. ≈13kVA/month and 4.3kVA/month or about as much as a CFL light bulb.

What is a "Search Mode" for an inverter?

An inverter would be in

• Discharge mode when grid power is not there and load is being fed from the battery through the inverter.
• Charging mode when grid power is resumed after a discharge & would consume generally at about 1/6 of the rated capacity of the inverter. (A 320 w or 400 va inverter will consume about 50 w during charging mode, till the battery gets charged to a voltage of 13.6 v (for a 12 v battery system) and switches over to standby mode.)
• Standby mode when grid power is there and the battery is charged fully and the typical consumption would be about 1/20 of the rated capacity. (For a 300 w inverter the standby mode consumption would be about 12 to 15 w).

Please explain the "Search Mode".

http://www.google.com/url?sa=t&source=web&cd=6&ved=0CDkQFjAF&url=http%3A%2F%2Fwww.ripenergy.ch%2Feng%2Finverter%2Fmanual%2Fmanual_20rev_207_FX_VFX.pdf&rct=j&q=search%20mode%20outback%20power&ei=GnmNTeP8EYnSsAPBmoiUCQ&usg=AFQjCNE103ndWYs3TrlAdG8UJrhfStorJA&cad=rja

Search "search mode".

I think we have a misunderstanding in terms... I think the thread is refering to a UPS (uninteruptable power supply) which uses a inverter but is not just an "inverter". The inverter to which I am refering can be used as a UPS but are mainly used as a component for PVs, hydro, wind power systems.

why not keep inverter in switched off mode after it reaches standby mode? When the grid power is not there let inverter come into use by a normally open switch ? Inverter is not an UPS ,so why keep the battery on float all the time or why keep inverter energized when grid power is ok.

Very nice and understandable answer

Search mode in a PV/wind/battery/domestic supply inverter, is when there is no load and it sits looking for one, by testing for a fall in impedance below a settable watts load level.

I.e it can be set to ignore inactive 'plug packs' and 'nuisance loads' that would otherwise keep it on.

The standby drain is typically reduced to around 500 mA at 24 Vdc = 12 W.

I don't think this varies with inverter size.

It's quite separate from losses in inverting - which obviously are higher if some nuisance load is keeping the full circuitry active.

You are right. Energy Star norms set by are followed by first Desk Top manufacturers, followed by TV mfgrs, followed by cell chargers, and so on; unfortunately not followed by many inverter/ UPS manufacturers. When I ordered my home inverter I asked my tiny supplier to supply with SMPS battery charger so that standby power used by the inverter is very small (less than 5 w).

As long as your battery power and inverter can easily carry your load within the energy specified,and proper scheduled regular maintenance of your battery and inverter is done,then the statement is authentic.

Some suggestions:

• Normal inverter design features the rectifier section to switched on continuously, causing consumption of power. We can ask for the inverter manufacturer to provide relay operated by-pass for the system to swichover to by-pass after the battery charging is complete.
• The inverter efficiencies are generally of the order of 65% to 85% as is commercially available, whereas it is possible to design inverters to have an efficiency of about 95% to 96%. To make the system less expensive the designer compromises on efficiency and provides it lower cost of purchase, but a higer cost to operate.
• The other part of efficiency is the energy storage-retrival efficiency. This efficiency comes to only about 60% to 66%----That is if the inverter supplies 1 kWh of energy during a mains failure it draws about 1.66 kWh of energy after restoration of the grid power to recharge the battery to the full charge status. Inverter manufacturer has no control over this part of energy loss.
• When you take the inverter efficiency and the storage efficiency into account. with a typical daily power failure for 2 hours, the figures quoted by you are reasonable from the overall sense.
• At least the trend should be to avoid the standby period float charge consumption for the 16 to 18 hrs in a day.
• If one does not require the power from the inverter, with automatic switchover, it would be prudent from energy angle to keep it in by-pass mode during the day time and switch on the inverter only if it is required.
• Generally the inverter in a typical home ends up consuming the figure worked out of about 30 kWh, even though individual consumption at different states may vary.

I am overwhelmed by the responses from a number of friends, offering their valuable suggestions, ideas etc. A big thank you to all who sent in their responses. In this connection, let me tell you of my experience with solar PV feeding my home inverter. I have installed a 60 W solar PV panel, 120 AHr battery and delinked the inverter from grid supply, using a toggle switch (to transfer back to grid supply during rainy days when sky is overcast). I use the battery-stored solar energy between 6 p.m. and 10 p.m. thereby helping the utility in my own small way by not drawing from grid during the peak time, when energy is at its highest cost. Also it has helped me to reduce my electricity bill considerably. I am yet to measure the inverter load using a consumption recording meter, as suggested during this interaction through CR4. Solar powered home inverter may be a good option to be considered by all. N T Nair, EKL

The latest addtion from you is very interesting and should make us all aware of what each one of us could do. GREAT.

Thanks for promoting a very good idea. Please do share the experience, measured values etc., for others. Please also share if there were any pit-falls, so that we need not go through the same or similar mistakes.