I'm looking to expand our stand alone system with an AC coupled grid inverter and PV array.
Can get a surplus 1.5kW grid inverter for $200 and 8 190W PVs for $1400..will give me approx 3-5kW hr in extra energy to be used during the day.
Aims are:
Less Battery discharging 5-10% DOD each day max (nite discharging most), No battery charging losses & DC Inverter conversion loss, less capital cost in no charge controller reg for extra PV array, greater surge rating if used during the day have both VFX3024E & Grid inverter supplying power.
This is the hot topic in AU for stand alone setups, at present, is there interest in the USA for AC coupled Inverters with standalone Inverters ??
The market for Grid Inverters in AU is 95% of the market so much cheaper than stand alone inverters
The way to go :). I just bought two inspire solar 1.5kw GTIs for $99 each (eBay aus) and your ideas are exactly the way I am going. With PVs so cheap I have max'ed out my classic 150 with 2.8kw on 24v batteries. Now a GTIS and 1200 watts connected to ac from my sw3024e for daytime use to heat the water. With this scheme I can plan a 2kw 48v inverter to replace the sw when/if it dies and the aged 24v/1024ah wet bank with 300ah Lifeypo4 48v bank.
These cheap Chinese made PVs are soo cheap that the money now is in the controllers and inverters so any scheme to include the relatively low cost GTIs into a stand alone system must be a winner.
I'm also watching these Lifeypo4 cells gradually decreasing in price.
Not that Midnite would agree with me but plentiful low cost PVs make mppt'ing less cost effective, perhaps the future will see each panel with its own built in controller electronics for mppt control to maximise current.
Dgd
Have been considering AC-Coupled GT Inverter additions here, more due to having some unused roof space that is a significant distance from the main off-grid power system.
Had wondered about using MicroInverters for this. BUT, had also wondered if surges might cause momentary AC voltage hits that could cause any AC coupled inverter to drop out for minutes. The off-grid inverters that any GT Inverter would be coupled to are SW Plus 5548s. Realize also that in the USA, there may be additional issues (in my case) with 240 V Split-Phase being made with two stacked inverters, but many of the surging loads would occur on only one of these two inverters and so on ...
I could run the experiment to see just what happens, and may do so in a few months.
BTW, here is an OB White Paper on their products used in AC Coupled environment:
http://www.outbackpower.com/pdfs_general/AC%20Coupling%20in%20Renewable%20Energy%20Systems%20White%20Paper.pdf
This may be generally familiar to you.
Thanks MN, this approach does not help sell CCs. Vic