MOAT: Module at a time installation (solar for the rest of us!)
"MOdule 'Atta Time" A disclaimer, I made this up. MOAT is my acronym, but you are free to steal it... On one hand, many MANY people actually want to install solar energy at their homes, but just can't. The main roadblocks are that 1) Most people rent homes and 2) most people are poor. The big idea of MOAT is that there is a way to install solar at your residence one-panel-at-a-time, without paying any major upfront cost. Further, it could be done in a way that is easily removable and does not affect the property where it is installed.
Most PV installations are put onto rooftops and are done all at once. Panels are rack mounted by professionals so that they get the best solar exposure, do not see shadows, and can be safely wired together and grid tied. Most state of the art installations have their modules wired in series like christmas light bulbs in a string. This adds the potential from each panel to the next, and the power from the whole string is fed into one big (expensive) power inverter. The inverter takes the ever-changing direct current from the panels and feeds it into the power grid at a fixed voltage and frequency. If one panel in this string gets shaded, the power from the whole string is affected. (As an experiment, I once disabled a 12,000 watt pv array by strategically frisbee-tossing a couple tortillas into the right places!) Anyway, the whole system usually costs tens of thousands of dollars, which requires financing. The conditions of financing often involve some kinds of state or federal incentives, which are great, but then require that the array never be moved in order to receive the benefits. The qualities are this in a nutshell:
- Require professional installation
- Exposure conditions are critical
- All-at-once installation, requires financing
- System must be permanently installed.
Enter the MOAT model
The whole point of MOAT (module at a time) is to address these holdups, and put more solar power in the hands of more people. In order for middle-class Americans with potentially limited budget and credit and housing options to have solar at their homes, the following criteria must be met:
- Low installation costs, DIY capability
- Ability to install solar in accessible locations, which may be less than perfect.
- Ability to physically install the system one panel at a time, eliminating need for financing
- Ability to rearrange, reconfigure, or relocate the system.
For this style of PV to take off, it will have to be done in a way that is safe, is allowed by local electrical codes, and is acceptable to housing owners who install it or allow tenants to install it.
The technology for MOAT
The base unit of installation is essentially a PV module that has its own microinverter on the back. This means that the solar panel produces power that is ready to grid-connect, without the christmas-light and expensive inverter scenario. Also, since each panel has its own inverter, a shadow (or wayward tortilla) will not take out the entire array. This makes it possible to put panels almost anywhere, not just on unobstructed rooftops. If it gets sun part of the day, then it helps your cause!
In order to connect the panels safely there will need to be a standardized power connection that does not allow misconnection. The microinverter will need to have a microcontroller that identifies conditions and prevents shock hazard. Finally, there will need to be one specially installed plug-in for the purposes of the grid-tie. This plug would have some sort of smart GFCI that not only identifies shock hazards, but monitors conditions of the PV array. It could be essentially a special block that goes right into a standard surface mount power box. Alternatively, it would be a small block that fits into a standard breaker slot back in the utility box.
As for the physical installation, if you are a homeowner and are going with the MOAT method, you have access to your rooftop. You may opt to have a professional install an empty rack or rail, and thereafter put the panels up yourself. The panels for MOAT could be made with easy snap-in latches for homeowners to use. If you are renting, your landlord may opt to put brackets all along one side of an apartment complex, along with that special aforementioned plug. Renters could purchase and install their own PV as time goes by. Mounting brackets could also be made for fence lines, or on-the-ground systems.
Finally, the cost of the system would have to be carefully designed into the product so that it could be adopted. What is an acceptable cost per module? Could a microinverter panel be made that would fit into the 'sweet-spot' that would make it affordable as well as effective at reducing ones power bills?
Like any technology MOAT is not a one-size-fits-all proposition. The solar exposure of an area, local electrical code, and attitudes of the neighbors all weigh heavily on any solar project. The microinverter technology exists, and PV costs continue to fall. I would encourage you to do the math and perhaps start your own business in the currently uncrowded sandbox I call MOAT.