Hi Mike.

It is possible to test the specs that are shown on the back of the panel with a multimeter. Of course you need the sun to do it ! Set up the panel in the full sun, middle of the day, and the panel sitting square to the direction on the sun as best you can by eye.

Put the multimeter on voltage DC and a range that is high enough to read to 25 + volts for 12 V panels. Then measure the open circuit voltage between the two output leads. It should match the Vmax spec shown on the back.

Put the multimeter on current DC and the leads in the correct holes. Range high enough to read the A current output on the back. Then connect it in circuit with the  two output leads. It should match the Asc current shown on the back.

Double check your meter is on the correct settings and the meter leads are in the correct sockets before you make the connection to the panel output or you may blow a fuse. Correct polarity is also important on some meters too.

Jaahn   

Jaahn wrote:

---

Hi Mike.

It is possible to test the specs that are shown on the back of the panel with a multimeter. Of course you need the sun to do it ! Set up the panel in the full sun, middle of the day, and the panel sitting square to the direction on the sun as best you can by eye.

Put the multimeter on voltage DC and a range that is high enough to read to 25 + volts for 12 V panels. Then measure the open circuit voltage between the two output leads. It should match the Vmax spec shown on the back.

Put the multimeter on current DC and the leads in the correct holes. Range high enough to read the A current output on the back. Then connect it in circuit with the  two output leads. It should match the Asc current shown on the back.

Double check your meter is on the correct settings and the meter leads are in the correct sockets before you make the connection to the panel output or you may blow a fuse. Correct polarity is also important on some meters too.

Jaahn   

 

---

 Diito 

and NOTE this carefully

"Double check your meter is on the correct settings and the meter leads are in the correct sockets before you make the connection to the panel output or you may blow a fuse. Correct polarity is also important on some meters too.""

Explorer wrote:

---

Thank You Gentlemen, Tried to follow Jaahns instructions but was getting a wildly fluctuating reading. Will talk to the auto elect. then throw the lot away & stick with the proven generator.

Thanks, Mike.

---

 I suspect you were doing the tests downstream from the regulator

The panels should be disconnected from the regulator & batteries ,measurements taken directly on the PANEL terminals

Jaahn wrote:

---

Explorer wrote:

---

Thank You Gentlemen, Tried to follow Jaahns instructions but was getting a wildly fluctuating reading. Will talk to the auto elect. then throw the lot away & stick with the proven generator.

Thanks, Mike.

---

 Hi Mike

As oldtrack said, it sounds like you have the regulator switching on and off quickly as there is no battery fitted.

If you told us what you were doing and some information on the hardware we could make a more useful comments. But it sounds like the panel is working to some extent.

Here is a suggestion ! Using a battery that is not fully charged. {Use a bit of power if necessary to use some up}. Using the Voltage DC range on the multimeter, connect to the battery terminals and it should read about 12.4V to 12.6 or so ! Then connect the panel and put the panel in the direct sun and watch the voltage. It should rise almost straight away half a volt or more, then as the battery is charged up it will continue to go up to 13 and more, climbing to the maximum of around 14.2V and then stay fluctuating down and back.   If it does that it is working OK. If you turn on some power items, lights etc it will drop a bit but go back up when they are turned off. 

Jaahn

-- Edited by Jaahn on Monday 24th of April 2017 08:31:36 AM

---

 Thanks, That's the sort of info that I need being techno challenged! Am going away & need to have an alternate power source thought I would be able to get away for a day or so & test but!!! 

This is one of two panels feeding into a Mppt regulator? 

Don't really want to take generator and panels so would need to know if working at the battery. 

Thanks MJP.

T1 Terry wrote:

---

Black multimeter lead in the COM socket of the meter, red lead in the Volts/Ohms etc socket. Meter set to high enough to read the 21.96v shown on the back of the panel one the scale that has a long flat line on top with a series of dashes under it, this is the symbol for DC. Red multi meter lead in the positive cable from the solar panel, black lead in the negative wire. Does the voltage read close to 22v?
Next, move the red lead in the multimeter to the 10 amp socket and the switch to DC amps (the same symbol as above but a different section on the dial) put the red lead in the positive cable and black lead in the negative cable. Tilt the panel and move it around till you get the highest reading, is that close to the 4.2amps specified on the back of the panel? Now you have finished the amps test move the red lead back to the Volts/Ohms etc socket position so you avoid damaging the multi meter. This is the same as suggested by many posters before me but it never hurts to say it again and it is a good practice to follow when using a multimeter, way to easy to damage them if you leave the red lead in the amps socket.

T1 Terry

---

 Hi, Many thanks, with that info & that from Jaahn I should be able to establish one way or another if I am comfortable with just taking the solar panels on this trip. The sun should be shining on the weekend for me to try. Tanks Mike.