Question of the day, Fooling a Grid Tied Solar System


Subject: fooling grid tie system solar panels


I have read lots of your writing and enjoy it.  I am wondering if you have, or know of anyone who had been able to bring up solar PV systems, that are designed for grid tie, when the grid is down by local excitation: Either with a small generator or with an inverter: And, what ramification that has on power production, and is it possible, and is there any danger to the solar system if you did not use the potential energy being supplied from the solar system?



My Answer:

I have thought about your question for a bit, and I think it’s important to note the distinction between the grid tied solar system and the more traditional solar system designed to serve the homeowner’s needs as part of the design criteria. I share this not for you, but for others who may read this post.

The Grid Tie System is designed around the Principle Goal of harvesting subsidies from the public treasury, all other design goals are secondary. We need remember there are now a number of systems called grid tied systems, and  guess we need know exactly which one we’re talking about. Engineers are still working on optimizing these system in order to reduce parts count and the cost of the equipment and install.  This often  means the system becomes even less flexible as newer systems for the specific purpose are created.  An example of that might be a panel that has a built in inverter than makes it even more difficult to tap into and store energy for your emergency or back-up use in a battery, there is likely a lot of different designs out there that are considered a grid tie system.

The more traditional Solar install captures subsidies as part of the plan, but it also serves the home owner in several ways, one is a fairly dependable and independent source of electrical energy, and of course there is a storage unit in the form of a battery of one technology or another.  When batteries are floated, and seldom discharged, they can and do last up to 30 years..

The home owner can enjoy power whether it be a long outage one or a short one, whether the sun shines or not… with the more traditional system.

The grid is a demand load, it varies greatly, and generating capacity that can’t store energy (like hydro, natural gas-fired plants do),  add complication and expense to the management of loads on the grid.  These added costs created by solar and wind power are still a hot discussion, and of course the Green Energy producers don’t want to pick up any of the associated costs they have created for dependable power producers. It’s possible these associated costs will default onto the backs of the  ignorant public and be taken out of the public treasury at some point as well because they are the easiest to give the bill to.  In the eyes of many taxpayers and voters,  a Green expense is the same as a Green profit, they can’t tell the difference.

Your home is essentially a mini grid load, you need figure out how to match the load with generating capacity. And you will need a generator running to assure you pick up the load WHEN that cloud shadow arrives. What you need know is your generator will need the capacity to carry 100 percent of your load to cover for that cloud shadow when it arrives! It’s likely possible that you could assure that a master switch is opened between you and the grid, and that you then start a generator and feed your own isolated power panel.  The grid tied solar system should not be able to tell the grid from your own power generation IF the frequency and voltage are within spec. If you have a very large solar install, and a very small generator and load, it’s possible the solar grid tie system could find the emulated grid a little too easy to bully, and it may shut down, or do something else you didn’t anticipate.  You’d only get a good answer from a person who’s done it, or the manufacturer of your specific system.

For the sake of keeping your homeowners policy intact and more, you need make every effort to keep your install legal, and meeting all code requirements. A fire or other mishap, that can be blamed on your ‘hack’ could impact your way of life in a big way.

In closing, scroll down to the comments section, we may have someone in our midst who has already experimented with their grid tie system in this way and has what you really need, ‘hands on knowledge’.

All the best,

George B

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3 Responses to Question of the day, Fooling a Grid Tied Solar System

  1. George B. says:

    One of the ‘hands on’ solar installers I know wrote me off line to make sure I knew there there were some great systems out there, (Like Outback’s system) that ‘sells’ KWHs back to the grid WHEN the battery is charged, and there is no more work to do for the system owner. I do understand this, and I hope others do to. Solar Power can be a great investment for the homeowner. The systems that provide us some backup, should be considered first, or so I think..

  2. Dave says:

    “The systems that provide us some backup, should be considered first, or so I think..”

    I doubt I would ever own any system that would generate power to the grid but when the grid went down you had no power. I never did understand the point!

  3. Russell Furzer says:

    As I pointed out to George in an email – i have stumbled over a company here in Australia that makes a series of inverters (Selectronics SP Pro) that will do grid feed with battery backup and can also start and integrate a generator (although won’t allow grid feeding of the generator output).

    The same inverter can be used off-grid and (for eg) would allow a 5kw inverter to augment a 5kw generator to power 10kw loads.

    Their marketing dept have not included all the info on one ad – there is a separate on-grid and off-grid info sheet.

    note the on-grid battery back up and off grid/leisure information is located on different tabs


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