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Need help with System and Vendor Selection in Carmel Valley San Diego.

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  • Need help with System and Vendor Selection in Carmel Valley San Diego.


    My roof line runs north - south, with little shade on either side. The house has a tile roof and is 15 yrs old.
    I have an electrical car with EVTOU2 rates.
    I plan on adding air conditioning soon. I'm told it will be a 5-ton unit.
    I will need a new panel to add the AC.
    Current consumption averages 825 kwH per month. (~10 kWh per year).

    I've received two quotes:

    1 - 12.6 kWh annually -- 26 LG 315s, SolarEdge SE7600A-US with optimizer = $32K including panel upgrade
    2 - 11.0 kWh annually -- 31 LG 275s, Enphase Micro Inverters = $26K including panel upgrade

    How many kWh annually should I add for the AC? I'd say I'm a normal guy who would prefer fresh air but can't sleep when its hot.
    What should I expect to pay per kw for a system?
    Any thoughts on installers?
    Is the trade off of more efficient panels vs. cost always worth it? Why would the one guy be quoting the 275s?

    Any thoughts, comments, suggestions or advice would be appreciated.



  • #2
    1.) On how much electricity A/C will add - tough call. Depends on weather and personal choice(s). I'm in 92026, vent the house at night and set the thermostat @ 79 deg. F. Easiest A/C season I had used 642 kWh. Worst used 1079 kWh. This summer is ahead of worst year by about 10% so far. Unit is 5 ton. house is 3200 ft.^2. I'd estimate many comp. neighbors use 2-3 X as much power for A/C as I do. Your climate is not as hot as mine ...............................2.) LG equipped systems often can be had for $3.50-$3.75/Watt before roof maint., elec. panel upgrade or other stuff with some sharp but fair negotiating. That $3.90/Watt looks too high. On the other hand, that $26K price almost looks too low. Read the fine print. and ask a lot of questions and expect a lot of requests from posters here wanting a PM for the vendor's name/#. .........................3.) If you have the room, the 275's are probably as fit for purpose as the 315's. The 315's have a little better area efficiency probably from some mfg. process improvements and also (I suspect) from removing some of the conservativeness in the performance specs that the 275's, being older, may enjoy. The 275's have been around longer and haven't had their specs stretched. They're A little longer in the tooth, but will probably give a good account of themselves. The 275's inventory may be running down and while still good, maybe a deal can be had. In either/any case, make sure you are actually getting what the contract says, that the goods are new and not sloppy seconds........................4.) For the same orientation, I'm a bit skeptical of the 315's putting out close to 20% more per installed Watt than the 275's. I'd run PV Watts and check that out. Someone may be dancing with your leg.


    • #3
      What JPM said, plus I'd like to add that, since you have EV and on EV-TOU2, you should already know the cost differential between peak and super off-peak rate is almost 3x in the summer. So if you can somehow shift your usage to maximize the generation credit during the day and use more in off-peak and super off-peak (eg. turning on AC after 6PM, charge EV after 12AM etc), you don't really need to size your system to cover 90%-100%. In fact, in my case, 60%-70% was good enough to get to net zero in $ terms. You price seems a little odd as noticed by JPM. For LG with SolarEdge and normally roof installation, $3.5-3.7/W is doable nowadays in SD.