Plug and play inverters

lsb61
lsb61 Registered Users Posts: 2
Hello all!
I am a virtual complete novice with regard to Solar systems. I am committed to eventually provide most if not all my power via solar. However, at this time I cannot afford 15K for a complete system. I have been looking for ways to make a dent in my power usage. I am currently making my own panels, and heavily researching how to safely put them in place to reduce what Im buying from my power company without taking out a second mortgage to do it.
Which brings me to plug and play inverters. I have seen quite a few available on line, but I have read here that many of you experienced solar guru's don't think they are safe.
Can anyone comment (in layman's terms please) why this is either safe or unsafe. Are there ways to make it safe? and if you don't feel it's safe then what suggestions might you have for a newbe that might be a safe but affordable alternative way to start.
Larry
P.S. I am not so much of a newbe that I don't have a basic understanding of what inverter's, charge controllers, and other components of these systems do and are for, but if you get too technical you'll loose me! lol

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Plug and play inverters

    Today--Building your own panels probably costs almost the same amount of money (and your time) as buying factory panels. And your DIY panels may last a few months or a year--Where factory panels should last 20-40 years.

    And, there is the problem with fire (these were "factory made" panels--but built the way most DIY panels are made):

    Panel Fire Question

    Regarding plug and play GT inverters, there are two main issues.

    The first is that it is not possible to, from a NEC/Fire Code point of view, to plug AC power "generators/sources" into home wiring safely... For example, say you have a 15 amp branch circuit. And you plug in 12 amps worth of GT Inverters. The total current available on that branch circuit is now >27 amps. Because electrical heating is equal to I2R -- You double the available current, you have 4x as much heating available--So now it is very easy to overheat the branch circuit by somebody else (spouse, kids) plugging into another wall outlet and start a fire (or if you have an appliance failure/short circuit somewhere).

    Next, because it is impossible (in my humble opinion) to ever get a plug in GT inverter approved--That means that most (some? all?) of the plug in units are not designed to meet UL/CSA/TUV/NRTL requirements and have never been tested to those limits (plus the materials are not "traceable" to NRTL requirements). What has been found by a couple readers here is that these GT units start to overheat/fail when operating at 50-60% of rated power unless additional fans are used to keep them cool...

    Then, there are the code requirements. NEC requires UL/NRTL (Nationally Recognized Testing Laboratory) approval. Building Departments require Roof Load calculations and permanent grounding (safety and lightning). Utilities want to know what generating sources are connected to their power grid. PUC (state public utility commissions) have billing requirements.

    And, newer utility meters will not turn backwards, some will even turn forwards and "charge you" for generating excess power, and/or even "call home" if your generating power to the network. In most (all?) areas, utilities have the right to disconnect you from the grid and cities can red tag your home if a DIY install is found (probably does not happen very often). In our area--Technically even an Off-Grid solar system can allow our utility to charge us for "stranding" their generation sources (i.e., the utility has taken out bonds based on my home using power--installing my own solar panels now places repayment of those loans/contracts "at risk").

    Are there people successfully installing and using guerrilla GT connected solar power systems out there? Yes.

    Are there solar GT power systems that are installed to code and still start fires. Yes.

    In general--It is better to do things both "right" and "to code". If not done to code--you run the risk of civil/criminal liability and your insurance company walking away walking away if there are no permits.

    There are solar leasing companies out there, at this time, that are offering very cost effective solutions (less than $2 per watt vs $5-$8 per watt installed typical GT install pricing). Even though I do not like leasing for various reasons--It is very difficult to ignore that option.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Plug and play inverters

    Welcome to the forum.

    The so-called plug and play GT inverters are a no-no because you do not know what the wiring is between the outlet you plug them in to and the circuit breaker panel. It has the potential of allowing more than 20 Amps of current to be carried on 14 AWG wiring which can not handle that much. None of these inverters are approved for installation. No inspector, utility, or insurance company would allow such an install for this reason.

    If you want to save money on your utility bill, by a Kill-A-Watt (or similar) meter for about $30 and start checking out everything you plug into the wall. You'll be amazed at the phantom load consumption or just plain inefficiency of some appliances. Sometimes little things like adjusting the video settings on the TV will save you a lot of power. Putting things on power bars so that they are really shut off when not in use is a big help too.

    For the most part, solar does not save money. It shifts costs from the monthly electric bill to a capital expenditure. Your utility may charge you $0.08 per kW hour while your solar provides power at a cost four or five times that. The higher the per kW hour charge and the better the install incentives are the more practical solar becomes.

    Be aware also that unless your power meter is the right kind, extra power generated by the solar and "sold back" to the grid will read as power consumed, making the bill higher and not lower.
  • lsb61
    lsb61 Registered Users Posts: 2
    Re: Plug and play inverters

    Thanks for the reply, Your suggestions confirmed my concerns, and that is clearly not the way to go.
    As I kind of hinted, like a lot of folks out there these days I am not made of money. So if you don't mind could you or anyone out there offer any suggestions about doing this without taking out a second mortgage to accomplish it. For example you stated you can buy panels for what you can make them for. I haven't found anything like that online, can you recommend vendors where your getting deals like that.
    Also wanted to ask you guys about inverter recommendations. As even a novice I understand the importance of this piece of the system. Prices are all over the place, and there are a million manufacturers.
    -First how do you correctly size what inverter you need if your objective is to eventually supply all your power with solar power.
    -Which manufactureres do you recommend (keeping in mind the bank account)
    -Can you start with smaller inverter capacity and then add to your system safely later?
  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Plug and play inverters
    lsb61 wrote: »
    Thanks for the reply, Your suggestions confirmed my concerns, and that is clearly not the way to go.
    As I kind of hinted, like a lot of folks out there these days I am not made of money. So if you don't mind could you or anyone out there offer any suggestions about doing this without taking out a second mortgage to accomplish it.
    Spend your money on conservation measures first. It's not as sexy as PV, but if you have leaky HVAC ductwork, thin or compressed attic insulation, single pane windows, leaky door weatherstripping, etc., addressing those issues is a much better use of your money than installing solar. And as others have said, although making your own panels may be an interesting project for you to do, it's probably not good economics.
    lsb61 wrote: »
    Can you start with smaller inverter capacity and then add to your system safely later?
    With microinverters, yes. With string inverters, not so much.
  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    Re: Plug and play inverters

    One issue with micro inverters doing an incremental increase would require a permit every time. That would be an added expense.

    Also you may need a new interconnect agreement with the utility each time.