Mixing of Photovoltaic Panel Types

[white stallion]

I have a client who made some photovoltaic collector panels. Now he wants to purchase some manufactured panels. The home made panel array produce around 76 VDC. The manufactured panels would produce a different voltage and current values. What should I expect?

 

[gadfly56]

I have a client who made some photovoltaic collector panels. Now he wants to purchase some manufactured panels. The home made panel array produce around 76 VDC. The manufactured panels would produce a different voltage and current values. What should I expect?

Okay, now I have this vision in my head of a good ol' boy with a MOCVD in his garage sputtering some home brew PV cells! :lol: Maybe he'll get featured on National Geographics new series "Redneck Rocket Scientists"!

 

[K8MHZ]

Okay, now I have this vision in my head of a good ol' boy with a MOCVD in his garage sputtering some home brew PV cells! :lol: Maybe he'll get featured on National Geographics new series "Redneck Rocket Scientists"!

Individual cells have been selling on eBay for quite a while now. Generally, you get a bulk with a guarantee of a certain amount being good. Some will be broken, some non functional. For example, you bid on a batch of 72 cells you may get a total of 100 cells to sort and test. Most of these are coming from Germany.

The price per watt is very low compared to factory assembled functioning modules. I am surprised we don't see more home brewing of modules and arrays.

 

[ggunn]

I have a client who made some photovoltaic collector panels. Now he wants to purchase some manufactured panels. The home made panel array produce around 76 VDC. The manufactured panels would produce a different voltage and current values. What should I expect?

It makes a difference how he wants to add them. Generally you can add dissimilar modules in series if their Isc (short circuit current) are within a couple percent, and you can combine dissimilar modules in parallel if their Voc (open circuit voltage) are within a couple of percent. If they are very different in both Isc and Voc, you cannot combine them without significant power loss.

That said, the inverter/charge controller/battery bank all have to be considered as well and their voltages, amperages, capacity, etc. all have to be reevaluated to see if the change is feasible. It's a non-trivial exercise.

 

[WizBandit]

Non Listed PV

Non Listed PV

Unless the DIY PV modules are going to be used in a "Hunting Cabin" or similar install they can't be used in a grid-tie situation so matching is a mute point. That being said pretty much the area of the cell is the place to match up, 6" cells x 60 of them for example. The current is not so much the issue as the VMpp or the operating Voltage. The MPP Tracking of the Inverter or Charge Controller will pretty much track the cells with the lowest Impp or (Amps @ operating I-V) Research PV IR curve.

 

[highvolts582]

Dont do it series but if your going to do this system use enphase or maybe solaredge

Dont do it series but if your going to do this system use enphase or maybe solaredge

I would not install home made panels for safety reasons. if you have modules of different wattage and voltage. You could probably use a micro inverter setup. Enphase makes an inverter that could do this as long as the modules are within specification of the microinverters. Microinverter is an inverter that mounts under each module that changes the DC to grid voltage eliminating inefficiency of a series wiring configuration that sucks the other modules down to the potential of the crappiest module in the whole series. They output AC current right from the array PV strings. This way you get the most out of each module. Also you can monitor each module separately. Solaredge inverters may also be able to achieve this they have microinverters under each panel that outputs the the most efficient voltage they still output dc from the array to regular inverters elsewhere.

 

[ggunn]

I would not install home made panels for safety reasons. if you have modules of different wattage and voltage. You could probably use a micro inverter setup. Enphase makes an inverter that could do this as long as the modules are within specification of the microinverters. Microinverter is an inverter that mounts under each module that changes the DC to grid voltage eliminating inefficiency of a series wiring configuration that sucks the other modules down to the potential of the crappiest module in the whole series. They output AC current right from the array PV strings. This way you get the most out of each module. Also you can monitor each module separately. Solaredge inverters may also be able to achieve this they have microinverters under each panel that outputs the the most efficient voltage they still output dc from the array to regular inverters elsewhere.

Solar Edge is not a microinverter system. It has add-on electronics to each module that tracks MPPT individually and uses DC to DC conversion to maximize current throughput and clamp the string voltage to (I believe) 400V. You have to use their inverter, because it communicates with the add-on boxes at the modules in order to adjust their output voltage.

 

[highvolts582]

Solar Edge is not a microinverter system. It has add-on electronics to each module that tracks MPPT individually and uses DC to DC conversion to maximize current throughput and clamp the string voltage to (I believe) 400V. You have to use their inverter, because it communicates with the add-on boxes at the modules in order to adjust their output voltage.

Your right they do adjust the voltage to 400 or so volts. They also output the voltage of around 1 volt per module when inverters are shut down or A/C disconnect/meter is shut off/pulled so 15 modules should read 15 volts dc on the DC strings which is great for fire fighters and life safety if your working on the systems or decide to Axe em. I believe if you shade an entire module the entire string will not be affected with solar edge. Enphase will definitely work solar edge maybe will work for mixed matched modules. I dont see why not but i never checked.

 

[SirSparky]

I wouldn't recommend that you touch his "homemade" array with a 10 foot pole. His panels are not U.L. listed and have no Mfr. warranty or any other standards of construction.
Having said that, his array voltage @ 76 VDC is also really low. You won't find a string inverter that will even turn on at that low of a voltage. That presents quite a problem in matching an inverter to his array. Lastly, you'll be hard pressed to find a U.L. listed solar panel that has similar current/voltage specifications to his "homemade" panel. The whole scenario presents lots of problems.