Greetings,

I've expanded my "solar guerilla" set up when I went from renter to home owner. I had 4 Microsine MS100 inverters in total that were humming along well for 6 years.

Now that 2 of the Microsine inverters have died, I'd like to replace the Microsine with a newer inverter. I'd like to stick with the existing panels I have. Can I string them together and use a small inverter like a SunnyBoy 700U? Here's my inventory:

Panel-------- Model-------Watts-----Quantity-----Voltage
Kyocera------KC50t---------50---------2-----------12v
Evergreen----EC94----------94---------1-----------12v
Evergreen----EC102GL----102---------1-----------12v
Evergreen----EC60----------60---------4-----------12v

Any thoughts solar friends?

Regards,
Dan

Wired in parallel, you will get the voltage of the lowest voltage panel.
Wired in series, you are limited to the lower current of the lowest panel:

Evergreen----EC94----------94---------1-----------12v
Evergreen----EC102GL----102---------1-----------12v
in series for 24V will limit to the amps the 94W panel (only looses 8 watts)
You want higher voltages - which gives lower amps, for the same watts, and uses smaller copper wire $$$
thusly paired to 24V:

Kyocera------KC50t---------50---------2 24v 100W (4.1A)
&
Evergreen----EC94----------94---------1 +
Evergreen----EC102GL----102---------1 24v 188W (7.8A)
&
Evergreen----EC60----------60---------2 24V 120W (5A)
Evergreen----EC60----------60---------2 24V 120W (5A)
will give close to 24V @ 21.9A (526W) STC rating, or about
370W real life output to the inverter.

The SB700U needs 120-150vdc I beleive ( vmp ) ... which is about (8 ) 12 volt panels in series

When you put a 4 amp panel in series with a 7 amp panel, it will be limited by the lower amp panel BUT, on the higher amp panel, it will operate above the rated vmp voltage ( watts is amps x volts ) ... most folks don't realise this. In a single string inverter like the SB, mixed match currents aren't that bad as the mismatched panels just raise the opertaing voltage. Now if you then parralled two series strings, you lose this ability.

While you won't get the rated wattage from the big panels, you will get closer to 80% of there rating as they will be operating at high voltage.... so its not a 50% hair cut on power.

As a best guess .. all in series you get a vmp of about 140-150 volts and lose about 50 watts due to mismatching ... but considering your panels, thats not that bad.

Simple test ... wire them in series, hook up a hair dryer, put in on low, that would be very close in load to the peak output of the panels ( 500 watts ) .. measure the V&I and you will know for sure what to expect before getting the SB.

I didn't realise that. I'll beware of it in the future.

so a 4A panel is "16V", 4A, in series with a 7A 12V panel ?
I'm not sure which panel sees the increased voltage, the lower amp one, or the higher amp one ?

Look at the VI graph of the panel. Take for example the KC130 ( just something I found quickly for an example )

http://www.kyocerasolar.com/pdf/specsheets/KC130GT.pdf

If you follow the amps vs voltage ... vmp is around 17 volts ( voltage maximum power ) ... now follow to half the amps, and the voltage increases to 21 volts. So 21 volts * 4 amps = 84 watts , much better than half of 130 which is 65 watts. This is called fill factor.

Also, the lower amp panel can put out more than 4 amps, how, look at the same graph and you will see lowering the voltage increases the current. So through the two in series with a good mppt inverter and what is likely to happen is the 4 amp panel will come up a bit in amps ( and lower in volts ) and the higher amp panel will come down in amps to match the smaller panel but increase the voltage, result is not a 50% decrease

This will ONLY work in a single series string. When you start parralleling strings, it is MUCH more importaint to have matched panels

that would still be quite a loss though. you may not have a whole lot of choices with it unless you use the 2 microsines for the best of your small pvs and get more high power pvs to go with a new and larger inverter. any leftover small pvs you sell.
solar guppy, i'll also take this time to wish you and everybody else a MERRY CHRISTMAS AND HAPPY NEW YEAR. you too jon wherever you are.