Supply/load side connection (tap)

Re: Supply/load side connection (tap)

Divenstuff wrote: »

My first post...I understand that NEC 690.64 allows for a load side connection...I could use some advice on the mechanics.

Situation:
Square D panel SC3040M200S 200 amp panel with 200 amp main breaker
Array size will be greater than 7.4 KW (max allowed 120% rule on load side connection)

Looking in my panel, the main breaker is supplied by exposed aluminum bars...I can access thes from the load side..what type of mechanical device would I use to connect the inverter to the supply side bars?

thanks

Sorry one option is if you can derate your main breaker to like 175 amps you can use the excess to support the solar. That should get you (120% X 200 amp) + 25 amps. More than enough head room for the solar system. In my case, the Utility said this was unacceptable because of my load profile (breakers installed) in the existing panel.

I didn't scream to hard as I am have a building being added to the property this summer and will need the extra panel capacity anyway. ;);)

Re: Supply/load side connection (tap)

Divenstuff wrote: »

I went all electric to stay off propane, when I built my house...I was ignorant of the limitations and requirements to install a large grid tied system.

I have a Square D All in one 200 amp panel....underground fed..I called Square D and they do not allow a line side tap...so my alternatives are go with max load side (120%) or upgrade the panel...I am going to contact SCE (utility) and see what I need to do to upgrade....any thoughts on a replacement panel that has a larger busbar capacity? thanks for all the advice

Here is what I did. This is a 400 amp service with a 200 amp mains panel and a 200 amp sub panel. All the loads are on the 200 amp main and the solar is wired to the 200 amp sub (derated with a 175amp breaker). We will soon add some loads to the sub panel for the new workshop building being constructed. The meter section of the panel is 400 amps and the utility pulled new wire to match that from the transformer to the meter. You can see the AC side PV disconnect and PV meter in the picture.

The second photo is the old service, single 200 amp.

Re: Supply/load side connection (tap)

BB. wrote: »

Have you done all of the conservation measures that make sense for your home (high SEER/COP heat pumps) and possibly a stand-a-lone heat pump hot water heater?

-Bill

If that was directed @ me here is what we have done so far.
1) added attic insulation mostly over 24 in deep
2) added solar power attic fans
3) replaced all light bulbs with CFL
4) replaced all computers with MAC mini's (normal draw about 18-25 watts)
5) replaced 1 of 2 AC units with high seer model, hoping for another rebate to do the other.
6) replaced deep freeze with Energy Star model
7) contract pending for solar hot water heater includes ultra high efficiency gas hot water heater and 80gal solar hot water storage. (up to 80% rebates and tax incentives)

To Do items:
1) replace 13 yr old fridge, would love another round of rebates first.
2) add reflective solar film to the south and west facing windows.
3) replace electric stove with Gas unit.

Re: Supply/load side connection (tap)

BB. wrote: »

Solar Dave,

Actually, I intended to ask Divenstuff--but your reply is great too.

And Dave, how much power (% and/or kWH per month) do you think you have saved through conservation / turning stuff off?

I have been telling people--If they have not yet worked on conservation, it is not unreasonable to try for a 50% reduction in their electricity use through conservation/energy star/lighting changes/downsizing computers/turning DVR etc. off when not used, etc...

-Bill

I would say at least a 30% reduction, some of the actions are fairly new but we kind of took the shot gun approach when the electric bill in mid summer hit $650+. Last month the bill with PV was $22 and of that only $4.40 was electric generation for off peak and we banked quite a bit of on peak. This month we moved the Swimming pool onto on-peak mid day to run it off the solar. Watching the numbers real close to see how that plays out.

I think the replacement of the other old 10 seer AC unit will help a lot, but I burned all the rebates and tax credits available, the first one was on the agenda to be replaced when the compressor failed, it just hastened the inevitable. Same with the old fridge, waiting on some kind of better incentive, maybe 2011.

Re: Supply/load side connection (tap)

mike90045 wrote: »

Bank your expensive peak hours, and split the pool time to before peak and/or after peak. That leaves you headroom to run the HVAC a bit. Most pools are over filtered

Yeah the peak bank is OK with about 2500 kWh for on peak, but we have been consuming all our off peak, hence sliding the pool to the on peak. Pool gets 4 hours a day now. However when Monsoon season hits in Aug, lots of nutrients hit it and 6-8 hours a day with a good shot of chlorine is required to keep it from going green. Water temps over 85F in the pool is the perfect soup for the algae. Pool temps will be well into the 90F range soon.

The plan is:
1) bank about 800 kWh for each summer month, June-Sept.
2) watch June usage to see if 800 kWh for on-peak is enough to break even with the addition of what we generate.
3) try and bank some off peak cause mid summer AC usage is 7x24.
4) the bank will be better next year, just added 2160 watts of panels on May 1

At the end of the year my fall excess is bought back by the utility @ $0.065 kWh.

Here is a shot of the last 48 hours with the pool pump on day shift, with no need for AC usage. Hehe, don't yah just hate electric dryer @ 4-6 PM on peak, but happy wife is happy life.
red = load, green = solar, blue = net, yellow = voltage.


In any case, the on peak has to always be the priority to hold the bill.