Grid tie inverter with power outage capability

Yeah,

I'm thinking for people who were thinking pure grid tie, it's a nice perk.

Jim

HiTech wrote:
Matt,

It does not provide backup, but it does provide power from the PVs (without a battery bank) which I don't see often. It's great to see more and more grid tie systems with backup. Most of the existing systems I have seen do not have it.

Jim

You're right. I totally forgot to comment on the unique feature. I agree it's interesting and I love to see innovation. I'm curious as to how they've designed this thing.
Unfortunately I don't think it will be of much use to most of my customers. Generally people's top priorities during an outage tend to be water and refrigeration. A submersible pump usually won't run on 1,500 watts without even considering the starting surge. I'm not sure if a residential refrigerator starting from a mid-cycle stop would start on that much power or not. I've have my doubts but no way to test it. Even then, keeping refrigeration going requires power when the sun isn't shinning.
For the uses mentioned, charging phones and what not, it would be pretty slick. Just not a substitute for a true back-up power system.

I have seen those. Seems like there are some tradeoffs to the distributed modular inverter designs. Nice for line loss and wire size for sure.

I am ever drawn to the other (low) end of the grid tie spectrum, some thing like this Grid tie MPPT inverter because it is inexpensive and sized to my system. I picture using it to offset some electrical charges in the RV or house. And the cool thing about grid tie is I imagine it to be able to supplement the output of a genset (who knows it it would really synch up) to provide more total watts capacity and less gas usage. Maybe it would let a marginal genset run an AC, or run AC at a higher altitude.

Jim

The "gaf" with the system I linked to is each panel has its own "micro"inverter, and puts out 240 watts of 240 volts a.c.

AFAIK, right now, MN and WI are the only two States that require the utility to cut a check for excess energy production from residential customers. In MN, the difference must be greater than $20.00/mo. or a credit is issued. The price paid for that energy is set at a tare rate just slightly below residential rate. My local utility, Xcel Energy, requires a 30 yr. contract, a separate meter is installed, physical installation has some standards, and all Energy Credits are ceded to the utility. They also incentivise solar to the tune of $1.75/w, currently. If you buy panels from an in-state mfg., the rate of incentive is higher. For alternative energy questions about pricing, incentives, and such: Dsire

The Sunnyboy inverter would put 1500w back into your house but that won't run mine. it would be handy to have for powering refrigerators, freezers, or other specific essentials. I would be better off with a battery back-up and larger inverters or, as I do it now in the case of a long outage, with a generator. At some point, I'll have panels on the property.

Fifteen years ago the system my utility used fed 100.00% of the power downstream of the home utility meter. It had it's own meter. It did not reverse the little wheel in the meter. Signing the contract the generator agreed to not tap into his system to bleed off power before it got to the meter.

I am happy to see things have changed.

Now I read the USA has enough shale oil to last to the year 3,000.

Beside raw material I wonder how many total kWh it takes to manufacture a solar panel. Careful now. The employee's participation and machinery costs are part of the audit. The silica to be grown into cells, the prep, the clean room, the laser slicing of the crystals, assembly and transportation from wherever. For off grid, the total energy audit for mining and refining metals, petroleum for the jar, H2SO4 for the electrolyte. Now compare all that to 24/7 falling water, a pelton wheel, distribution network to a home.

Matt,

It does not provide backup, but it does provide power from the PVs (without a battery bank) which I don't see often. It's great to see more and more grid tie systems with backup. Most of the existing systems I have seen do not have it.

It seems grid tie with backup might be nice for certain types of RVing, especially when the RV is not in use or when on a metered camp site.

I could picture using it with my RV PVs at the house when I don't need them for charging the camper batteries. I have the panels and battery here and a cheap grid tie system hooked to a load dump on a solar controller to tap those unused watts is tempting. It only makes economic sense if the grid tie unit is very inexpensive though, otherwise the payback is too long to justify the purchase.

Jim

First of all, grid-tied PV systems that sell power back to the utility and incorporate a battery bank to provide the home's power needs during an outage are quite common. Xantrex and Outback have both offered this type of system for 10 years or more. The SMA product referenced by the OP is a grid tie only inverter, it will not provide back-up power during an outage. However, SMA does make a product called the Sunny Island that will turn their grid-tie inverters into a battery back-up system. This ends up being functionally very similar to a Xantrex or Outback system but at a greater cost.
As for sending power to the Utility; in most places that is called Net Metering. Net Metering has been allowed by law since probably the 1970's. Some utilities and states have different regulations but most use just straight net metering.
The way this works is that any power generated by your solar system is either used by your home or sent backwards thru the meter into the grid. The utility instals a bi-directional meter so they can account for this current flow. In this way you are effectively selling your solar electricity to the utility at the same rate you buy it.
For example, if your home uses 1,000 kWh per month and your solar system generates 800 you would have only purchased 200 form the utility and would only be billed for that amount. If your solar system generated 1,200 that month you would build a 200 kWh credit with the power company. The credit can usually be carried forward for up to 12 months. Net Metering does not allow for the utility to write you a check for excess power generation. To do this you would need a Power Purchase Agreement. PPAs generally have them paying you a wholesale rate for excess power rather than the retail rate you buy it at. Because of this most homeowners don't install a system that will generate more power than they use over the course of a year. This leaves them a utility bill that is essentially zero except for certain taxes and fees you can't get out of.
Buy the way, I instal these systems for a living.

Interesting. Ignoring tariffs and regulations for a minute and speaking pure technically, wouldn't a grid tie system hooked in to the electrical box, downstream of and closer to the loads than the meter, just reduce power drawn through their meter?

Jim

This has probably changed but out west when I checked into "co-generation" the power company said "It don't work that way!"

We purchase 100.00% of your generated power, period. You take nothing for yourself. Not even for lightbulbs for the generator room.

Every last kWh you consume must come through our meter.

We realize the power we sell to you is 400% more expensive than the power we purchase from you but after all WE ARE THE PROVIDER.