Newbie here.

stevespens · November 14

I picked up some solar panels for next to nothing from a friend. I have a few basic questions about them to get me started. They are as follows:

Evergreen ES-180-SL

VP 25.9

IP 6.9

VOC 36.9

Is 7.78

I realize some of these abbreviations don't match what I've read here. Can someone clarify for me?

As far as my count goes, there are 108 cells. 18X6. Does this seem right? They are 3'x5'. And does it mean they are 12v or 24v?

I'll keep this first post simple until I get some info.

Thanks for listening.

stevespens · November 14

Isc 7.78

littleharbor2 · November 14

Old Evergreen panels, nice They made a good product in their day. I'm not familiar with this model. I'm going to guess they are two strings of 54 cells by the voltage given. This would not make them 12 or 24 volt, more like 18 volt, nominal. Nowadays, with MPPT controllers it really doesn't matter what "Nominal" voltage they are. Just run them in strings that work with the voltage requirements of the controller.

stevespens · November 15

Thanks for the reply.

When you say "strings", you mean run parallel?

I have 11 panels, so a total of 1,980 watts. (Advertised) So let's call it 2,000 watts.

So now I have my homework to do. Do I go parallel for max amps or in series for voltage? What's best to charge the batteries? My brain says parallel to charge batteries. Am I on track? Keeping in mind this is for emergency backup power.

littleharbor2 · November 15

Series raises voltage while current remains at the individual panels current. Parallel raises current while the voltage stays the same.
You want to series wire, close to, but never over the limit of the MPPT controller. And let the controller do its magic. You will get very near full output watts into your battery this way while using smaller wire and fewer overcurrent devices.

stevespens · November 15

Ok, thank you, that's a good start. Gives me an idea of where to go from here.

I'm sure I'll have more questions as I go.

Thanks.

stevespens · November 15

So after doing some research, the open circuit volts per panel is 32.6. Times 11 is 358.6 volts. Does this mean I would need a MPPT controller capable of handling over 358.6 volts??? And a current capacity of only 7.78 amps? From what I've seen, that would be very expensive for a controller with that capacity.

Thanks.

BB. · November 16

It is slightly more complicated than 11*Voc... But correct as a starting estimate. The details include Voc rises as panels temperatures fall... Voc is at Standard Temperature (25C/77F). If you are in a coldst/subfreezing climate, the Voc can rise quite a bit (upwards of 20% or so)... Vmp (and Voc too), also fall when panel temperatures rise... Live in a hot climate, then Vmp falls (again upwards of 20% or so) (panels in full sun, hot weather, no wind).

And regarding Vpanel-input max voltage--For MPPT solar chargers, yes, as you go above ~150 VDC Vpanel-max, the prices of the solar chargers increase (and there are fewer choices out there).

If you are doing a Grid Tied system (solar panels=>GT Inverter=>house AC wiring), on average, this is the cheaper solution (Vmp-array>150-400+ VDC).

There are lots of details to work out here.... More or less, smaller systems can use lower voltage battery banks/solar arrays... But as the system Wattage increases, then usually higher Vpanel and Vbatt voltages make for cheaper and easier to wire systems... It is much easier to send 100+ Volts longer distances than to send 12 volts (smaller diameter wire, less voltage drop, etc.).

Because of the hardware choices that need to be made, highly suggest that you start with defining your loads (12 VDC, 120 VAC, 240 VAC, etc), how many Watt*Hours per day by season, can you install the array in a open field/sunny area or not (panels basically output near zero useful power when even partially shaded).

Getting the hardware first, then trying to piece a system together with used/on sale equipment, without an overall design usually does not work out well...

-Bill

littleharbor2 · November 16

If you're starting from scratch you might look at some of the, so called, "All In One" inverter/chargers. They can handle high voltage with built in MPPT charge controllers. The24 or 48 volt systems can be had for as low as under $400 usd.

stevespens · November 17

Littleharbor2, after watching many videos, I think the combination units may be a good route for me. They can run several different ways, power from batteries, power from array, charge and use array at the same time, charge from utility,,,,,,, A lot of flexibility yet simple for the beginner.

I'm looking at the EG4 3000w and the Rich Solar 3000w units. Any thoughts?

And as for batteries, do you like 2 100ah or 1 200ah? After doing some calculations, I think 200ah"s is a good place to start.

Thanks.

littleharbor2 · November 19

I do like the EG4 products. I recently installed a EG4 6000XP and am VERY impressed with the quality and value. Love all the built in breakers, so simple to install.
Definitely the 200ah. over the 100's. The fewer individual batteries in your bank, the better.

stevespens · November 19

Thank you Littleharbor.

Newbie here.

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