Siemens Panels.....How to add to?

H2SO4_guy

Hi,

We are looking at an off grid straw bale home in Colorado. It has 12 panels that are Siemens 90 watt units, Solar boost RV charge controller, (50 amps max) Surrette flooded batteries, (1000 AH @ 24 VDC @ 20 hr rate I think) Trace 4024, T240 transformer, and Square D QO series breakers.

Since Siemens panels are not made anymore, I don’t know how to add to the array. We have 6 of the older 52 watt Caruzo panels that I could series up to add 270 watts to the array, but they would be a bit different and would lose 14 watts per pair of panels for a total loss of 42 watts. I have looked on ebay for panels, but none show up. I know Siemens have been sold to Shell and I think that was spun off from Shell also.

Would it be better to sell the panels and look at other options or try to buy them as we can. I don’t know how much power we will need, but probably will end up running the Kohler 11,000 genny. (Modified by Kohler to run on LP gas and converted to be 120 volts only, not 220 volts)

Thanks,

Skip in Independence Missouri
We want more Independence and less Missouri

mike95490

Re: Siemens Panels.....How to add to?

H2SO4_guy wrote: »

probably will end up running the Kohler 11,000 genny. (Modified by Kohler to run on LP gas and converted to be 120 volts only, not 220 volts)

That's a lot of generator, unless you have an all electric house. ( 11KW ? )

icarus

Re: Siemens Panels.....How to add to?

I'm sure the experts will weigh in with more learned opinion but here's mine,,,

I have run mixed strings for years. I'm sure that there are some disadvantages to doing so, but in my experiance they are minimul.
The much bigger issue is the voltages of the panels and the strings. I think that if you keep the panels reasonably close to one another in wattage you shouldn't be a problem.

I'll be curious to hear from others on the subject.

Good luck,
Icarus

niel

Re: Siemens Panels.....How to add to?

you don't want to get rid of them if they are still functioning. you could use any current 12v pv with a vmp at 17.0v or slightly higher and the wattages do not have to match your original 90w pvs as long as the newer pvs will not be in series with the original 90w pvs. have the new pv strings parallel to the old 90w pv strings. you could even get a 24v pv with a vmp of 34 or 35v and parallel that to the old pvs. the current from the new strings will add to what you already get from the old pvs and just watch that the input current does not exceed 40a or you should get another controller. the 5.4a rating from the old pvs will be 6x5.4=32.4a and 40-32.4=7.6a of expansion room.

crewzer

Re: Siemens Panels.....How to add to?

Sulfuric Acid Guy,

As indicated, adding panels to an existing array, or reconfiguring an array, requires that you pay close attention to two basic rules. One is that the PV modules wired in series have substantially the same Imp specs. The other rule is that the PV strings wired in parallel have substantially the same Vmp specs.

For example, my “48 V” array consists of two series-strings wired in parallel. Each string consists of four BP (SX) 60 W modules (“6 V” configuration; 8.4 Vmp x 7.12 A Imp), one Kyocera 120 W module (16.9 Vmp x 7.10 A Imp), and one Sharp 123 W module (17.2 Vmp x 7.16 A Imp). Allowing for manufacturing tolerances, the Imp current specs for the different brand/model modules are “close enough”. Accordingly, each string spec ends up at 67.7 Vmp x 7.10 A Imp, and the total array spec is 67.7 Vmp x 14.2 A Imp. The revised 966 W spec is 99.5% of the nameplate ratings. Under clear and crisp mid-day skies (summer humidity is a problem in my area), my array easily produces 14.2 A.

Deftly applied, this mix ‘n’ match approach can be very handy. As illustrated above, it’s allowed me to gradually expand my array, although the BP 60 W modules and the Kyocera 120 W modules are now out of production. And, when the time comes to "grow" the array to a "60 V" configuration (there is a sorta-plan here), I can expand the array by adding one more ~125 W module to each string. Current options include the same Sharp 123, the Mitsubishi 125, and the Kyocera 130, which is the same form factor as the old KC-120.

I recommend you consider some additional factors as you plan your system. One is that it appears that you’re moving to a much colder climate, so temperature correction factors should be considered. The STC Voc of a “24 V” array is ~42 V. Factoring in the TCF of 125% for temperatures down to -40 (F or C), the array Voc could hit ~52 V in the winter. The SB50 is rated for 57 V max, so you appear to be OK. Always worth a check, though.

On a related note, the SB50 is actually NEC rated for 40 A Isc (see manual page 9). For “24 V” applications, this means a PV array rated at ~1100 W STC. As a practical matter, something in the 1,300 W STC range is probably the real limit. But, that’s a decision you’ll have to make, especially when you consider that the Colorado combination of higher altitude, colder weather, and reflections from snow and/or ice will probably cause considerable power (current) output excursions, especially in the winter. If you decide you’ll need a larger array, you’ll likely need a larger controller as well.

HTH,
Jim / crewzer

H2SO4_guy

Re: Siemens Panels.....How to add to?

I think this might be worth a look at on adding to the Siemens panels. On comparing the specs of the Siemens SP90 (90 watt panel) and SP75 (75 watt panel). These are basically the same panels, made at the same time frame, have the same look and have more differences that you would think. The voc for the SP75 is 21.7 vs the SP90 is 21.6. No big deal there. Here is where it gets weird. If you parallel 6 SP75 modules, you get 450 watts. So the Impp is 4.4 * 6 = 26.4 Amps, while if you parallel 5 SP90’s you get 450 watts BUT the Impp is 5.4 * 5 = 27 Amps. Why is the BIG difference when the panels are basically the same? The SP75 Isc is 4.8 *6 = 28.8 while the SP90 is 6.1 * 5 = 30.5. Another big difference. What I wanted to do was use 15 of the SP90 with 3 strings. Then I can get 6 of the more available SP75’s, wire them in parallel for a string. Then series up all 4 strings for a total of Voc 86.8 (Approx) @ 26.4 – 27 Amps.

The panels would be wired in parallel to the cominer box which is very close, and in the combiner box could be wired in series to get 4 strings. 5 would be possible, but 6 would push the limits of voc @ 129.6 volts for an MX-60. I don’t know what the NEC limit is on voltage for the MX-60, so if someone could chime in it would be appreciated. 4 strings would provide 1800 STC of panels, and 5 would be 2250. I could go with a Flex 80, which might not be a bad idea right off of the bat. Can the MX-60 handle 60.2 Amps of Isc?

Another idea is to sell all of the panels and buy new ones, but when I want to upgrade again, it may be the same issue that the panels that I want are no longer made. So why take the hit on selling the panels and plan on buying SP75’s or SP90’s.

Again, I really appreciate everyone’s help and insight on all of this.

Skip

System2

Re: Siemens Panels.....How to add to?

I am not technical at all . Because of a hurricane which took one Siemens SP 75 panel from my roof I am looking for a replacement at a reasonable price . May be you can help me in solving this problem . I live in Belgium but the roof on the house is located in the island Grenada ( West Indies )

icarus

Re: Siemens Panels.....How to add to?

happy wrote: »

I am not technical at all . Because of a hurricane which took one Siemens SP 75 panel from my roof I am looking for a replacement at a reasonable price . May be you can help me in solving this problem . I live in Belgium but the roof on the house is located in the island Grenada ( West Indies )

Do you have other panels in an array? How are they arranged? Series? Parallel? Series/Parallel etc?
If so find a panel with similar specs.

If not the world is open.

Tony