Grid tie inverters to boost genset or PSW inverter output?

If you have an MPPT solar controller (to decouple the PVs from the battery voltage), and a battery powered inverter that can synch up to an existing AC source (rare but they do exist), I agree. Grid tie units tend to be a lot less expensive though.

It would seem an inverter running off the batteries while being charged off solar was the way to go. The batteries could cover power shortfalls (like passing clouds, surges, etc.) The solar would minimize the total AH pulled from the batteries, and recharge then when power requirements of the inverter were less then power output from the solar. You would only need enough solar to cover average loads + a little extra to top off the batteries VS enough solar to cover peak loads (which could be 3 to 4 times higher - for seconds / minutes at a time) think nuking something frozen for 90 seconds while the AC is on. Even a simple car battery could support the additional load of a microwave - for 90 seconds.

X2

Hi Mena,

Simple answer. If you draw 100 amp-hours out of a battery then it takes approximately 110 amp-hours to replace the energy so used.

If on the other hand you run directly from solar there is nothing to replace.....

Maybe Jim can explain something to me. How is running a load directly from battery less efficient than running it from solar? My apologies if I've asked this before I can't remember if I did. :)

msiminoff wrote:

2oldman wrote:

a grid tie inverter doesn't really help me with my issue which is starting the air-conditioner compressor when the generator is in "Eco mode".

My inverter does that.

My inverter starts the A/C too... the point is that my solar can't because I only have 320W of it.

So, beyond starting a large inductive load... what might the benefits be of paralleling a grid-tie solar inverter to a (grid-tie) inverter-generator like a Honda EUXXXXi?

-Mark

That's the main point I was thinking off - using solar when just a few watts short to start something up. I was also thinking of using it if the camper is in a place where it is plugged in. you could offset the cost of parasitic loads or even provide a little surplus energy back to the grid, if you don't need that power for battery charging or you have a surplus.

But but there is a potential savings around fuel efficiency in a genset usage scenerio. Solar grid tie would let the genset burn less gas when running than on its own. It can be more efficient to generate AC right from the solar without the battery, controller and battery bank inverter in the equation. Even more so if the solar controller is PWM and the grid tie inverter is actually MPPT - the batteries can be switched out of the loop to let the PVs run at maximum efficiency.

So one use case is running the genset for something other than battery charging, and wanting to use as little gas as possible doing it.

jim

MrWizard wrote:
btw the honda is not 'grid tie'

Ya', that's why I wrote it parenthetically...
However, the inverter in the Honda EU's functions similarly to a grid tie inverter in that it pairs and synchronizes with a 2nd source and maintains line voltage (up to it's rated output. I have paired mine with several other sine wave AC sources (inverter-generators and 12Vdc inverters) with no ill effects.

MrWizard wrote:
None...

What about fuel economy while running A/C from a small generator.
In the places I camp, I cannot easily replenish my fuel supply... so saving just a gallon or two of gasoline and/or propane is a big deal.

None... btw the honda is not 'grid tie'

2oldman wrote:

a grid tie inverter doesn't really help me with my issue which is starting the air-conditioner compressor when the generator is in "Eco mode".

My inverter does that.

My inverter starts the A/C too... the point is that my solar can't because I only have 320W of it.

So, beyond starting a large inductive load... what might the benefits be of paralleling a grid-tie solar inverter to a (grid-tie) inverter-generator like a Honda EUXXXXi?

-Mark

There is no $22 model. If you click on any of the options for the inverters at that link they're all relatively expensive. The cheapest inverter is the 300watt one at $89. I think the $22 misleading title is for a watt meter.