Solar newbie in Los Angeles - Sunpower vs. LG panels - seeking advice!!!

[J.P.M.]

according to the salesman, the 37 sunpower 335's (12395kw) system will produce 13212 kwh over the year...
the Hyundai sales proposal is for 35 270kw (9450w) panels-and said to produce 12873 kwh over the year

in spite of all my readings, this is the part I still don't understand how 35x270 is producing what 37x335 will produce (less 2-3%), as when I do the calc, I too see the output tobe 25% less..

is this salesman B.S.??

Run PVWatts for your location and orientation and get your own estimate. Something is not correct. Maybe the orientations used are different. The output estimates ought to be fairly close per installed kW for the same orientations/locations.

[russ]

Run PVWatts for your location and orientation and get your own estimate. Something is not correct. Maybe the orientations used are different. The output estimates ought to be fairly close per installed kW for the same orientations/locations.

Have the salesmen actually seen the location? Possibly one is basing his output on more accurate information for your particular location, orientation.

[paris401]

the sunpower saleman has sent his rep to see the house, the Hyundai has not yet..

running pvwatt, the closest locale to Montauk ny is shoreham
the sunpower system comes up 14860, while the Hyundai comes up to 11,329.. that's a whopping 30%+ difference... could it be that the SP quote they underestimated, while the Hyundai overquote it??

I can understand a 'salesman' being overly optimistic by 10% (the key word is salesman) , but don't understand the SP underquoting by the same 10%...

making an 'informed' decision is not as easy as I thought...

[J.P.M.]

Have the salesmen actually seen the location? Possibly one is basing his output on more accurate information for your particular location, orientation.

That thought crossed my mind as well. Happens a fair amount - especially now with solar customers being more plentiful for peddlers than targets for German U-boats in 1940.

[J.P.M.]

the sunpower saleman has sent his rep to see the house, the Hyundai has not yet..

running pvwatt, the closest locale to Montauk ny is shoreham
the sunpower system comes up 14860, while the Hyundai comes up to 11,329.. that's a whopping 30%+ difference... could it be that the SP quote they underestimated, while the Hyundai overquote it??

I can understand a 'salesman' being overly optimistic by 10% (the key word is salesman) , but don't understand the SP underquoting by the same 10%...

making an 'informed' decision is not as easy as I thought...

You may still be missing the point.

Per PVWatts:

Sunpower: 14,860 kWh/yr./12.395kW system = 1,204 kWh/yr per nameplate kW. @ $4.14/Watt.

Hyundai: 11,329 kWh/yr./9.45 kW system = 1,200 kWh/yr per nameplate kW. @ $3.75/Watt.

Essentially identical. Sunpower may be able to fit more capacity on your roof because smaller footprint, which may well be the reason for the size diff. Remedy: Reduce your usage by about 20%, skip the S.P. and save more yet.

[ButchDeal]

Essentially identical. Sunpower may be able to fit more capacity on your roof because smaller footprint, which may well be the reason for the size diff. Remedy: Reduce your usage by about 20%, skip the S.P. and save more yet.

The difference in cost could likely get you a pretty high efficiency new heatpump along with some weatherization likely gaining at least the 20% consumption savings.

[paris401]

You may still be missing the point.

Per PVWatts:

Sunpower: 14,860 kWh/yr./12.395kW system = 1,204 kWh/yr per nameplate kW. @ $4.14/Watt.

Hyundai: 11,329 kWh/yr./9.45 kW system = 1,200 kWh/yr per nameplate kW. @ $3.75/Watt.

Essentially identical. Sunpower may be able to fit more capacity on your roof because smaller footprint, which may well be the reason for the size diff. Remedy: Reduce your usage by about 20%, skip the S.P. and save more yet.

I 'finally' (I think) get it... thanks... I already changed half the bulbs to led's, and disconnected '2' fridges for the winter (its a summer house) as rarely is anyone there from oct-march... i'll wait till I get the other 2 quotes b4 I make a decision, but SP appears not the way to go..

one further question... is one roof mounting system better then the rest... today's salesman was pretty hyped over ironridge.
thanks

[Venice]

Energy audit for new construction suggestions?

Do an energy audit, reduced your load by 20% and go with the non S.P. system. For starters, your bills will be a lot less and the 20% larger footprint of the non S.P. system will meet the same load fraction as the S.P. system for a lot less money - as in 20% smaller (electrical size) for about 20% less per nameplate Watt, or about 2/3 as much up front total $$.

I'm building new construction, so I'm basically estimating what our energy usage will be in the future. The house will have all new very energy efficient appliances and LED lighting and since we are by the beach, we will very rarely use the AC. We do have an EV. The various reps have thrown around 800-1000 kW/month based on all our anticipated needs.

Is there a more precise way of estimating our usage?

[rhedayi]

according to the salesman, the 37 sunpower 335's (12395kw) system will produce 13212 kwh over the year...
the Hyundai sales proposal is for 35 270kw (9450w) panels-and said to produce 12873 kwh over the year

in spite of all my readings, this is the part I still don't understand how 35x270 is producing what 37x335 will produce (less 2-3%), as when I do the calc, I too see the output tobe 25% less..

is this salesman B.S.??

yes I call BS

[rhedayi]

I'm building new construction, so I'm basically estimating what our energy usage will be in the future. The house will have all new very energy efficient appliances and LED lighting and since we are by the beach, we will very rarely use the AC. We do have an EV. The various reps have thrown around 800-1000 kW/month based on all our anticipated needs.

Is there a more precise way of estimating our usage?

Well, with a pool pump at my house, a 70 inch LED on most of the day and 4 fridges (dont ask) I use about 700 kw a month without heater or ac use.....Venice is pretty nice climate and heater is cheaper than a/c in terms of electricity.....I think you should probably see your bill before even considering solar to be honest. If I did not have the crazy summer a/c bills, I can live with a $125 bill on a monthly basis.....save the cash from the solar

[Venice]

Attaching the racks before the roof is finished?

Well, with a pool pump at my house, a 70 inch LED on most of the day and 4 fridges (dont ask) I use about 700 kw a month without heater or ac use.....Venice is pretty nice climate and heater is cheaper than a/c in terms of electricity.....I think you should probably see your bill before even considering solar to be honest. If I did not have the crazy summer a/c bills, I can live with a $125 bill on a monthly basis.....save the cash from the solar

I was originally going to wait to make a decision about solar until we had lived in the house for a year. However, the roofer and GC highly recommend placing the racks before the roof is completed. I know solar installers will warranty the penetration of roof; however, I'd rather the roofing company integrate the racking system and warranty the roof. I'm trying to be conservative in our usage estimate so as to not overshoot.

[rhedayi]

I was originally going to wait to make a decision about solar until we had lived in the house for a year. However, the roofer and GC highly recommend placing the racks before the roof is completed. I know solar installers will warranty the penetration of roof; however, I'd rather the roofing company integrate the racking system and warranty the roof. I'm trying to be conservative in our usage estimate so as to not overshoot.

you are going to have a hard time getting a good estimate fromt the solar companies, they want to sell you the biggest they can sell you. Will you have a pool, what is the square footage, do you have many TVs, do you have a EV, kids home all day? I had solar companies suggest much bigger systems than I went with ( 5.2kw system.) My neighbor with a similar house was sold a 10kw system. Sure they based it on his electricity but the kitchen and living room have 18 65 projector bulbs and my guess is he never swapped them for LEDs or CFLs. Those lights are on for hours in the evening.....18x65 = 1170 watts, something like running a microwave or a blow dryer for hours.....anyhow with LEDs and low a/c usage and no pool, E efficient appliances , not a lot of exterior lighting (think malibu etc) you will probably be surprised at how little energy you will use, my guess is you can expect to be around 500 kw per month.

[J.P.M.]

The difference in cost could likely get you a pretty high efficiency new heatpump along with some weatherization likely gaining at least the 20% consumption savings.

Thanx. That's the type of thing that really saves $$'s.

[J.P.M.]

I'm building new construction, so I'm basically estimating what our energy usage will be in the future. The house will have all new very energy efficient appliances and LED lighting and since we are by the beach, we will very rarely use the AC. We do have an EV. The various reps have thrown around 800-1000 kW/month based on all our anticipated needs.

Is there a more precise way of estimating our usage?

Start with your usage for your present and recent past situation. Estimate the reduction or increase in building energy use and adjust new estimate using that estimate.

Energy use is a tough thing to estimate without prior bills. For a new dwelling it'll be a blend of old usage patterns laid on top of a new and probably more efficient structure. But that new structure will probably be larger and thus use more energy than the old one on an absolute basis - meaning it may just use more energy due to being bigger, but do it more efficiently.

Total energy use depends on the climate of the location, family size, use patterns, attitudes about energy use, dwelling size and characteristics, building age, construction quality, and many other things. Similar size families in very similar houses can have very different annual energy use. That's one of many reasons why buying a house with existing solar on it will most likely result in an incorrectly sized system for the new owners - either too big or too small. A little off sizing is good, but a system sized for a family that uses 20,000 kWh/yr sold to a family that uses half that much may well mean that the new owners at least partially paid a higher price for an oversized solar array they can't (or won't) fully utilize. Too small and they'll need more panels/inverter.

Many outfits listed on the net can provide what's called title 24 energy compliance documentation for CA.. Such info may already exist for what you are building.

[ButchDeal]

I was originally going to wait to make a decision about solar until we had lived in the house for a year. However, the roofer and GC highly recommend placing the racks before the roof is completed. I know solar installers will warranty the penetration of roof; however, I'd rather the roofing company integrate the racking system and warranty the roof. I'm trying to be conservative in our usage estimate so as to not overshoot.

Unless you find a roofer that is also a solar installer this is probably not the best tactic. Solar flashing requires the shingles be fully installed and I would not count on a roofer knowing proper racking installation nore optimal layout.