A newbies DIY solar install

[ning]

Battery backup will definitely run a pump, but it's got to be sized for it. I use Enphase's system; we had to go with 2 of their batteries (10kWh each) to be able to manage the desired backup loads (I ended up putting in 3 for 30kWh for more headroom). I can't speak for power walls but I'd imagine it's similar.

 

[ning]

Has anyone in California purchased a whole house battery backup without solar to get through the safety-shutoffs? California is against all internal combustion it seems, so not sure if you can get traditional whole home generators.

AFAIK the prohibition against small off-road engines doesn't have any real effect before 2024, and it only affects portable generators starting in 2028.

I don't think it affects stationary generators like whole-house units (which presumably are rarely used... unless it powers your off-grid house lol).

 

[ponytug]

Again, just for what it is worth, Tesla did upgrade the surge power ratings on their Powerwalls a few months ago, so the comments may have been (were) valid at the time.

Nevertheless, I think @Carl_NH's experience with a generator is typical; generally, you need more than twice the running current to start a well pump, and certainly more than the LRA. (Makes sense, as the poor well motor has to overcome all of the water weight (pressure) above it as it begins to rotate.) I have heard 5X running current as a rule of thumb, but the actual design is everything (copper/aluminum windings, brushed/brushless, 1800/3600 rpm, gas vs diesel, flywheel size, and how the rated power was actually defined).

With any inverter system, stable loads work really well, but loads that switch on suddenly, or rapidly on/off can cause stability issues. I read of someone with a 3D printer that had a nozzle heater that cycled rapidly to maintain temperature and that ended up causing flickering as the batteries tried to predict where the load was going.

My two cents for someone installing a battery system would be to ensure that they have whole house surge protection in the main panel as you are adding $$$$ of electronic equipment tied to your main power lines.

All the best,

Peter

 

[beowulf]

Beowolf,

I got the same feedback from Tesla on the Power Wall to hook into our solar - we have the same pump size 1.5 HP, down 375' - it draws 22-23 amps on start up 13 amps running.

We had a 6500W starting, 5500W (or 24 AMP 240V) continuous genset, which really struggled with the pump so we barely used water during an outage, so I upgraded to a 7500W (32 Amps 240V ) continuous 9500 starting and it handles it fine.

Carl, I assume you are referring to a portable generator with 7500W - 9500 starting? I may look into that as I consider my options. Thanks for the information.

 

[beowulf]

With any inverter system, stable loads work really well, but loads that switch on suddenly, or rapidly on/off can cause stability issues. I read of someone with a 3D printer that had a nozzle heater that cycled rapidly to maintain temperature and that ended up causing flickering as the batteries tried to predict where the load was going.

Peter

I think well systems with storage tanks would make sense as they do not need to go on and off frequently - then the booster pump from the tanks to a pressure tank and then running into the house would be a 110 (?) and could be operated off a smaller generator. Our well does not have a storage tank but the the house my daughter is building on our property will have tw0 3000 gallon tanks - one for domestic use and one for Calfire.

 

[ponytug]

Wow, the local fire group wants 30,000 gallons of storage or 10,000 with black iron piped sprinklers in the house...

Yes, FWIW, My well pump is set to run for a couple of hours at a time, so that it runs infrequently.

All the best,

Peter

 

[beowulf]

Wow, the local fire group wants 30,000 gallons of storage or 10,000 with black iron piped sprinklers in the house...

Yes, FWIW, My well pump is set to run for a couple of hours at a time, so that it runs infrequently.

All the best,

Peter

The local fire here requires a minimum of 2500 gallons dedicated to fire use. That can mean a 5,000 gallon tank with float switches set so that the domestic use never causes the level to go below 2500 gallons - the domestic use taps the top 2500 gallons. On the recommendation of a well guy we went with two 3000 gallon tanks - his reasoning was that he has seen 5000 gallon tanks bulge, and he prefers a separate tank for domestic and just let the fire storage tank sit - he says fresher house water that way. We also are required to have sprinklers - and a booster pump for those.

 

[bitseeker]

Approximately 11 years ago, we installed a 68-panel, 17-KW system on a purpose-built tall building to get above much of the neighbor's tree shading.
The system uses Enphase brand microinverters (one under each panel) so that shading that panel only reduces its output. You may not have a shading issue.
The output of the microinverters is 240 V, so it is lots safer than a long high-voltage DC run.
Current Enphase systems provide for battery fallback if utility power fails. We have frequent and a few long outages. I see that you do not.
The gird-tied system banks and retains overproduction. We have 20 MWh in that bank now. Power company bills ~ $8/month for infrastructure.
The cost of electricity will go up, so the bank is earning interest. This system will (and has) powered an EV.
We have switched from oil and propane to 100% electric.

There were lots of good prior ideas and I have not read all of the posts which may cover my suggestions.

Suggestions:
Plan very carefully.
Use large conductors to reduce parasitic loss.
Plan for maintenance. (a squirrel got on our roof and chewed through two cables, requiring panel remove/re-install.)
Use the required anti-seize for the stainless fastener to the aluminum structure.
If it is an older roof, re-roof that part, at least, before racking and panels go on top.
Use tall roof-to-racking risers. Airflow under the panels cools them better on hot days and increases output.
Do it!

 

[Carl_NH]

Carl, I assume you are referring to a portable generator with 7500W - 9500 starting? I may look into that as I consider my options. Thanks for the information.

Yes - it is a portable genset and the 32 Amps is @ 7500W and at 9500 surge is 43 amps and the pump draws 22-23 amps starting- 13 amps running - you can tell when it kicks on but it handles it fine.

 

[LittleBill21]

Yes - it is a portable genset and the 32 Amps is @ 7500W and at 9500 surge is 43 amps and the pump draws 22-23 amps starting- 13 amps running - you can tell when it kicks on but it handles it fine.

I have used 3500 watt generators to run well pumps. it really depends on the individual well. and ours were deep 240 units, not jet pumps