Well, I did ask. And the points expressed are all good ones.
1. Yes. This is a lot to spend on one 120 volt pump. I haven't yet measured how many watts the pump consumes over a week or two to get an average daily use figure on the watts needed. I may discover I don't need 4, 5, or 6 panels. But I don't see that the life of the pump has anything to do with the payback period for the system. The only real consumables I see are the batteries. And that is built-in to MOST (though not all) renewable energy situations. But running directly off the panels is an idea I may need to explore. What I like about the battery situation is it helps keep the voltage to the inverter a little more constant.
2. I don't want a tank. I understand the gravity feed thing. And that could be a very definite plus. But it would be difficult to place a tank around our house where it would be aesthetically pleasing. Second, there is a hygiene issue to consider. I worked at a school that had a huge one. I've been up in there. Keeping a raised water tank clean and safe is harder (and more expensive) to do than you might think. And freezing can be an issue.
3. I don't favor changing the pump to a 12 or 24 volt one. It would involve digging a trench and running VERY heavy duty #1 or #2 wire almost 50 or 60 feet (probably even further when you add the run from the solar panels). By using the inverter to power the existing pump I believe we'll experience lower voltage loss from the inverter out to the pump house. And yes - I'll lose some power in the conversion at the inverter. But that is on the 12 volt side - not the pump side.
4. I see this as a stepping stone towards a larger system.
We have higher power rates in our city than in most parts of the country. Our city utility made a bad deal and locked into high rates back when Enron was still in business. Now we're stuck with those rates. It was a stupid move by the manager (who got fired for it). But we're still stuck with high rates. And we can't switch to another power company. Thus, I've been on a quest to lower our electric bill.
While watering some new grass seeds over a two month period, I discovered that the pump was driving our monthly electric bill up. I'm also going to find out if a more efficient pump is an option.
We switched to a heat pump/hybrid water heater (the old electric one had died). This has dropped our use by about $15 a month. Not sure what the life of the unit will be. So don't know if it will ever pay for itself.
We've upgraded our insulation. That is almost always a wise plan.
We upgraded our HVAC unit to a 16 SEER hybrid unit. That saved us between $75 and $!00 a month during the Summer. Our Winter electric use is slightly higher than before, but we use less than a third of the propane our older gas-pack was consuming. That brought our equal pay plan from $465 a month to $345 for electricity. I'm aiming to get it under $300. I may not make it. But that's my goal.
I don't have the money now to convert totally to solar. But I'm looking ways to do it gradually. And the cost of panels is coming down - albeit slowly.
Again, thanks for the good input. I knew I'd get honest feedback. I do recognize that this does look like a lot of money for what must seem like a small gain.
Bach On